1
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Stevens MC, Taylor NM, Guo X, Hussain H, Mahmoudi N, Cattoz BN, Leung AHM, Dowding PJ, Vincent B, Briscoe WH. Diblock bottlebrush polymer in a non-polar medium: Self-assembly, surface forces, and superlubricity. J Colloid Interface Sci 2024; 658:639-647. [PMID: 38134672 DOI: 10.1016/j.jcis.2023.12.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/08/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023]
Abstract
Whilst bottlebrush polymers have been studied in aqueous media for their conjectured role in biolubrication, surface forces and friction mediated by bottlebrush polymers in non-polar media have not been previously reported. Here, small-angle neutron scattering (SANS) showed that a diblock bottlebrush copolymer (oligoethyleneglycol acrylate/ethylhexyl acrylate; OEGA/EHA) formed spherical core-shell aggregates in n-dodecane (a model oil) in the polymer concentration range 0.1-2.0 wt%, with a radius of gyration Rg ∼ 7 nm, comprising 40-65 polymer molecules per aggregate. The surface force apparatus (SFA) measurements revealed purely repulsive forces between surfaces bearing inhomogeneous polymer layers of thickness L ∼ 13-23 nm, attributed to adsorption of a mixture of polymer chains and surface-deformed micelles. Despite the surface inhomogeneity, the polymer layers could mediate effective lubrication, demonstrating superlubricity with the friction coefficient as low as µ ∼ 0.003. The analysis of velocity-dependence of friction using the Eyring model shed light on the mechanism of the frictional process. That is, the friction mediation was consistent with the presence of nanoscopic surface aggregates, with possible contributions from a gel-like network formed by the polymer chains on the surface. These unprecedented results, correlating self-assembled polymer micelle structure with the surface forces and friction the polymer layers mediate, highlight the potential of polymers with the diblock bottlebrush architecture widespread in biological living systems, in tailoring desired surface interactions in non-polar media.
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Affiliation(s)
- Michael C Stevens
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Nicholas M Taylor
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; Syngenta, Jealott's Hill International Research Centre, Bracknell RG42 6EY, UK
| | - Xueying Guo
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Hadeel Hussain
- Diamond Light Source Ltd, I07 Beamline, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Najet Mahmoudi
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, UK
| | - Beatrice N Cattoz
- Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, Oxon OX13 6BB, UK
| | - Alice H M Leung
- Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, Oxon OX13 6BB, UK
| | - Peter J Dowding
- Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, Oxon OX13 6BB, UK
| | - Brian Vincent
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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2
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Gubała D, Slastanova A, Matthews L, Islas L, Wąsik P, Cacho-Nerin F, Ferreira Sanchez D, Robles E, Chen M, Briscoe WH. Effects of Erucamide on Fiber "Softness": Linking Single-Fiber Crystal Structure and Mechanical Properties. ACS Nano 2024. [PMID: 38334316 PMCID: PMC10883039 DOI: 10.1021/acsnano.4c00114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Erucamide is known to play a critical role in modifying polymer fiber surface chemistry and morphology. However, its effects on fiber crystallinity and mechanical properties remain to be understood. Here, synchrotron nanofocused X-ray Diffraction (nXRD) revealed a bimodal orientation of the constituent polymer chains aligned along the fiber axis and cross-section, respectively. Erucamide promoted crystallinity in the fiber, leading to larger and more numerous lamellae crystallites. The nXRD nanostructual characterization is complemented by single-fiber uniaxial tensile tests, which showed that erucamide significantly affected fiber mechanical properties, decreasing fiber tensile strength and stiffness but enhancing fiber toughness, fracture strain, and ductility. To correlate these single-fiber nXRD and mechanical test results, we propose that erucamide mediated slip at the interfaces between crystallites and amorphous domains during stress-induced single-fiber crystallization, also decreasing the stress arising from the shear displacement of microfibrils and deformation of the macromolecular network. Linking the single-fiber crystal structure with the single-fiber mechanical properties, these findings provide the direct evidence on a single-fiber level for the role of erucamide in enhancing fiber "softness".
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Affiliation(s)
- Dajana Gubała
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Anna Slastanova
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Lauren Matthews
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
- Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, U.K
| | - Luisa Islas
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Patryk Wąsik
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
- Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, U.K
| | - Fernando Cacho-Nerin
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | | | - Eric Robles
- Procter & Gamble Newcastle Innovation Centre, Whitley Road, Longbenton, Newcastle NE12 9TS, U.K
| | - Meng Chen
- Procter & Gamble Technology (Beijing) Co., Ltd., 35 Yu'an Rd, Shunyi District, Beijing 101312, China
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
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Taylor NM, Pilkington GA, Snow T, Dowding PJ, Cattoz BN, Schwarz AD, Bikondoa O, Vincent B, Briscoe WH. Surface forces and friction between Langmuir-Blodgett polymer layers in a nonpolar solvent. J Colloid Interface Sci 2024; 653:1432-1443. [PMID: 37804612 DOI: 10.1016/j.jcis.2023.09.146] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/28/2023] [Accepted: 09/24/2023] [Indexed: 10/09/2023]
Abstract
Optimization of boundary lubrication by tuning the confined molecular structures formed by surface-active additives such as surfactants and polymers is of key importance to improving energy efficiency in mechanical processes. Here, using the surface forces apparatus (SFA), we have directly measured the normal and shear forces between surface layers of a functionalised olefin copolymer (FOCP) in n-dodecane, deposited onto mica using the Langmuir-Blodgett (LB) technique. The FOCP has an olefin backbone decorated with a statistical distribution of polar-aromatic groups, with a structure that we term as "centipede". The effect of lateral confinement, characterised by the surface pressure, Πdep, at the air-water interface at which the LB films are transferred, was examined. Normal force profiles revealed that the thickness of the LB films increased significantly with Πdep, with the film thickness (t > 20 nm) inferring a multi-layered film structure, consistent with the interfacial characterisation results from synchrotron X-ray reflectivity (XRR) measurements. The coefficient of friction, µ, between the LB films spanned two orders of magnitude from superlubricity (µ ∼ 0.002) to much higher friction (µ > 0.1) depending nonlinearly on Πdep, with the lowest friction observed at the intermediate Πdep. Molecular arrangement upon LB compression leads to the multilayer film with a structure akin to an interfacial gel, with transient crosslinking facilitated by the intra- and inter-molecular interactions between the functional groups. We attribute the differences in frictional behaviour to the different prevalence of the FOCP functional groups at the lubricating interface, which depends sensitively on the degree of compression at the air-water interface prior to the LB deposition. The LB films remain intact after repeated compression (up to pressures of 10 MPa) and shear cycles, indicating strong surface anchorage and structural robustness as a load-bearing and shear-mediating boundary layer. These unprecedented results from the friction measurements between LB films of a statistical copolymer in oil point towards new strategies for tailoring macromolecular architecture for mediating efficient energy dissipation in oil-based tribological applications.
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Affiliation(s)
- Nicholas M Taylor
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Georgia A Pilkington
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Tim Snow
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Peter J Dowding
- Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, Oxon OX13 6BB, UK
| | - Beatrice N Cattoz
- Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, Oxon OX13 6BB, UK
| | - Andrew D Schwarz
- Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, Oxon OX13 6BB, UK
| | - Oier Bikondoa
- XMaS, The UK CRG Beamline, European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38043 Grenoble, France; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Brian Vincent
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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Grimes PJ, Jenkinson‐Finch M, Symons HE, Briscoe WH, Rochat S, Mann S, Gobbo P. A Photo-degradable Crosslinker for the Development of Light-responsive Protocell Membranes. Chemistry 2023; 29:e202302058. [PMID: 37497813 PMCID: PMC10946628 DOI: 10.1002/chem.202302058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 07/28/2023]
Abstract
The achievement of light-responsive behaviours is an important target for protocell engineering to allow control of fundamental protocellular processes such as communication via diffusible chemical signals, shape changes or even motility at the flick of a switch. As a step towards this ambitious goal, here we describe the synthesis of a novel poly(ethylene glycol)-based crosslinker, reactive towards nucleophiles, that effectively degrades with UV light (405 nm). We demonstrate its utility for the fabrication of the first protocell membranes capable of light-induced disassembly, for the photo-generation of patterns of protocells, and for the modulation of protocell membrane permeability. Overall, our results not only open up new avenues towards the engineering of spatially organised, communicating networks of protocells, and of micro-compartmentalised systems for information storage and release, but also have important implications for other research fields such as drug delivery and soft materials chemistry.
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Affiliation(s)
- Patrick J. Grimes
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | | | - Henry E. Symons
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Wuge H. Briscoe
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Sebastien Rochat
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
- School of Engineering Mathematics and TechnologyUniversity of BristolAda Lovelace BuildingTankard's CloseBristolBS8 1TWUK
| | - Stephen Mann
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Pierangelo Gobbo
- Department of Chemical and Pharmaceutical SciencesUniversity of TriesteVia L. Giorgieri 1Trieste34127Italy
- National Interuniversity Consortium of Materials Science and Technology Unit of TriesteVia G. Giusti 9Firenze50121Italy
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Bharatiya B, Wlodek M, Harniman R, Schweins R, Mantell J, Wang G, Warszynski P, Briscoe WH. Solution and interfacial self-assembly of Bacillus subtilis bacterial lipoteichoic acid (LTA): nanoclustering, and effects of Ca 2+ and temperature. Nanoscale 2022; 14:12265-12274. [PMID: 35861484 DOI: 10.1039/d2nr00595f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Lipoteichoic acid (LTA) is a major structural and functional molecule in the Gram-positive bacteria membrane. Knowledge of LTA adsorption at interfaces and its solution self-assembly is crucial to understanding its role in bacterial adhesion and colonisation, infections and inflammations. Here, we report the self-assembly behaviour of LTA extracted from Bacillus subtilis, a Gram-positive bacterium, in an aqueous solution using cryogenic transmission electron microscopy (Cryo-TEM) and small-angle neutron scattering (SANS) and its adsorption behaviour at the solid-liquid interface using atomic force microscopy (AFM) imaging and quartz crystal microbalance with dissipation monitoring (QCM-D). The Cryo-TEM results indicated the formation of spherical LTA micelles that decreased in size on addition of calcium chloride (CaCl2), attributed to charge neutralisation and possible formation of stable Ca2+-bridges between the phosphate groups on neighbouring LTA chains. Analysis of the SANS data from the polydisperse LTA aggregates in solution using the two Lorentzian model revealed the existence of two correlation lengths, which could respectively account for the presence of LTA micelle clusters and the local structure arising from LTA intra-molecular interactions. In the presence of CaCl2, the decrease in the correlation lengths of the clusters indicated possible disruption of H-bonding by Ca2+, leading to poorer water-LTA interactions. At higher temperatures, the correlation length corresponding to the clusters increased, indicating a temperature assisted growth caused by the fluidization of micellar core and dehydration of the polar LTA chains. AFM imaging showed that adsorption of LTA aggregates at the SiO2-water interface was significantly prompted by the addition of CaCl2, also confirmed by QCM-D measurements. These unprecedented nanoscopic structural details on the morphology of LTA aggregates in solution and at the solid-liquid interface add to our fundamental understanding of its self-assembly behaviour hitherto underexplored.
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Affiliation(s)
- Bhavesh Bharatiya
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Magdalena Wlodek
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Robert Harniman
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Ralf Schweins
- Institut Laue-Langevin, DS/LSS, 71 Avenue des Martyrs, Grenoble 38000, France
| | - Judith Mantell
- Wolfson Bioimaging Facility, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Gang Wang
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Piotr Warszynski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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6
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Slastanova A, Campbell RA, Islas L, Welbourn RJL, R P Webster J, Vaccaro M, Chen M, Robles E, Briscoe WH. Interfacial complexation of a neutral amphiphilic 'tardigrade' co-polymer with a cationic surfactant: Transition from synergy to competition. J Colloid Interface Sci 2022; 606:1064-1076. [PMID: 34487929 DOI: 10.1016/j.jcis.2021.08.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/22/2021] [Accepted: 08/02/2021] [Indexed: 11/24/2022]
Abstract
HYPOTHESIS Neutral amphiphilic PEG-g-PVAc co-polymer (a "tardigrade" polymer consisting of a hydrophilic polyethylene glycol, PEG, backbone with hydrophobic polyvinyl acetate, PVAc, grafts) can form complexes at the air-water interface with cationic dodecyltrimethylammonium bromide (DTAB) via self-assembly. Compared to anionic SDS, cationic DTAB headgroups are expected to interact strongly with the negatively charged OH- groups from the partial dissociation of the PVAc grafts. We anticipate a transition from synergistic to competitive behaviour, which is expected to be dependent on the surfactant structural characteristics and concentration. EXPERIMENTS DTAB/PEG-g-PVAc mixtures were investigated using a combination of dynamic and equilibrium surface tension measurements, neutron reflectivity (NR) at the air-water interface, and foaming tests. We varied the concentrations of both the DTAB (0.05 to 5 critical micelle concentration, cmc) and that of PEG-g-PVAc (0.2 and 2 critical aggregation concentration, cac). FINDINGS Our results show that the interfacial interactions between DTAB and PEG-g-PVAc were both synergistic and antagonistic, depending sensitively on the surfactant concentration. At DTAB concentrations below its cmc, a pronounced cooperative adsorption behaviour was likely driven by the hydrophobic interactions between the DTAB tail and the PVAc grafts and the attraction between the DTAB headgroups and the partially dissociated -O- groups in the partially hydrolysed PVAc grafts, forming a mixed layer. This synergistic adsorption behaviour transitioned to a competitive adsorption behaviour at DTAB concentrations above its cmc, leading to polymer-surfactant partition, forming a "hanging" polymer layer underlying a surfactant monolayer at the interface. We postulate that DTAB/PEG-g-PVAc complexation in the bulk contributed to partial depletion of the mixture from the interface. We therefore consider this polymer/surfactant system to be a moderately interacting system at the air-water interface. No discernible differences in the foaming behaviour were observed between the DTAB/PEG-g-PVAc systems and the pure surfactant. Our results suggest that surfactant headgroup characteristics (particularly charges) were crucial in determining the structure and composition of polymer-surfactant complexes at the air-water interface, as well as the foamability and foam stability, whilst the coexistence of the synergistic and competitive adsorption behaviour is attributed to the unique architecture of the tardigrade polymer with amphiphilicity and partial charge, facilitating different surfactant-polymer interactions at different DTAB concentrations.
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Affiliation(s)
- Anna Slastanova
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Richard A Campbell
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK; Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, Grenoble 38042, France
| | - Luisa Islas
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Rebecca J L Welbourn
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - John R P Webster
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Mauro Vaccaro
- Procter & Gamble, Temselaan 100, 1853 Strombeek-Bever, Brussels, Belgium
| | - Meng Chen
- Procter & Gamble Beijing Innovation Centre, 35 Yu'an Rd, Shunyi District, Beijing, China
| | - Eric Robles
- Household Care Analytical, Procter & Gamble Newcastle Innovation Centre, Whitley Road, Longbenton, Newcastle NE12 9TS, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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7
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Ishak MI, Jenkins J, Kulkarni S, Keller TF, Briscoe WH, Nobbs AH, Su B. Insights into complex nanopillar-bacteria interactions: Roles of nanotopography and bacterial surface proteins. J Colloid Interface Sci 2021; 604:91-103. [PMID: 34265695 DOI: 10.1016/j.jcis.2021.06.173] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/25/2021] [Accepted: 06/30/2021] [Indexed: 10/21/2022]
Abstract
Nanopillared surfaces have emerged as a promising strategy to combat bacterial infections on medical devices. However, the mechanisms that underpin nanopillar-induced rupture of the bacterial cell membrane remain speculative. In this study, we have tested three medically relevant poly(ethylene terephthalate) (PET) nanopillared-surfaces with well-defined nanotopographies against both Gram-negative and Gram-positive bacteria. Focused ion beam scanning electron microscopy (FIB-SEM) and contact mechanics analysis were utilised to understand the nanobiophysical response of the bacterial cell envelope to a single nanopillar. Given their importance to bacterial adhesion, the contribution of bacterial surface proteins to nanotopography-mediated cell envelope damage was also investigated. We found that, whilst cell envelope deformation was affected by the nanopillar tip diameter, the nanopillar density affected bacterial metabolic activities. Moreover, three different types of bacterial cell envelope deformation were observed upon contact of bacteria with the nanopillared surfaces. These were attributed to bacterial responses to cell wall stresses resulting from the high intrinsic pressure caused by the engagement of nanopillars by bacterial surface proteins. Such influences of bacterial surface proteins on the antibacterial action of nanopillars have not been previously reported. Our findings will be valuable to the improved design and fabrication of effective antibacterial surfaces.
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Affiliation(s)
- Mohd I Ishak
- Bristol Dental School, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK; School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; Faculty of Engineering Technology, Universiti Malaysia Perlis (UniMAP), Perlis, Malaysia
| | - J Jenkins
- Bristol Dental School, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK
| | - S Kulkarni
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
| | - T F Keller
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany; Physics Department, University of Hamburg, Hamburg, Germany
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Angela H Nobbs
- Bristol Dental School, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK
| | - Bo Su
- Bristol Dental School, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.
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8
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Gubała D, Taylor N, Harniman R, Rawle J, Hussain H, Robles E, Chen M, Briscoe WH. Structure, Nanomechanical Properties, and Wettability of Organized Erucamide Layers on a Polypropylene Surface. Langmuir 2021; 37:6521-6532. [PMID: 34015220 DOI: 10.1021/acs.langmuir.1c00686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding the nanostructure and nanomechanical properties of surface layers of erucamide, in particular the molecular orientation of the outermost layer, is important to its widespread use as a slip additive in polymer materials. Extending our recent observations of nanomorphologies of erucamide layers on a hydrophilic silica substrate, here we evaluate its nanostructure on a more hydrophobic polypropylene surface. Atomic force microscopy (AFM) imaging revealed the molecular packing, thickness, and surface coverage of the erucamide layers, while peak force quantitative nanomechanical mapping (QNM) showed that erucamide reduced the adhesive response on polypropylene. Synchrotron X-ray reflectivity (XRR) was used to probe the out-of-plane structure of the surface layers. Static contact angle measurements further corroborated on the resulting wettability, also demonstrating the efficacy of erucamide physisorption in facilitating control over polypropylene surface wetting. The results show the formation of erucamide monolayers, bilayers and multilayers, depending on the concentration in the spin-cast solution. Correlation of AFM, XRR and wettability results consistently points to the molecular orientation in the outermost layer, i.e. with the erucamide tails pointing outward for the surface nanostructures with different morphologies (i.e., bilayers and multilayers). Rare occurrence of monolayers with exposed hydrophilic head groups were observed only at the lowest erucamide concentration. Compared with our previous observations on the hydrophilic surface, the erucamide surface coverage was much higher on the more hydrophobic propylene surface at similar erucamide concentrations in the spin-cast solution. Furthermore, the structure, molecular orientation and nanomechanical properties of the spin-cast erucamide multilayers atop polypropylene were also similar to those on industrially relevant polypropylene fibers coated with erucamide via blooming. These findings shed light on the nanostructural features of the erucamide surface layer underpinning its nanomechanical properties, relevant to many applications in which erucamide is commonly used as a slip additive.
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Affiliation(s)
- Dajana Gubała
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Nicholas Taylor
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Robert Harniman
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Jonathan Rawle
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Hadeel Hussain
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Eric Robles
- Household Care Analytical, Procter & Gamble Newcastle Innovation Centre, Whitley Road, Longbenton, Newcastle NE12 9TS, United Kingdom
| | - Meng Chen
- Procter & Gamble Beijing Innovation Centre, 35 Yu'an Rd, Shunyi District, Beijing 101312, China
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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9
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Matthews L, Ruscigno S, Rogers SE, Bartlett P, Johnson AJ, Sochon R, Briscoe WH. Fracto-eutectogels: SDS fractal dendrites via counterion condensation in a deep eutectic solvent. Phys Chem Chem Phys 2021; 23:11672-11683. [PMID: 33978002 DOI: 10.1039/d1cp01370j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Glyceline, a deep eutectic solvent comprising glycerol and choline chloride, is a green nonaqueous solvent with potential industrial applications. Molecular mechanisms of surfactant self-assembly in deep eutectic solvents are expected to differ from those in their constituent polar components and are not well understood. Here we report the observation of self-assembled SDS fractal dendrites with dimensions up to ∼mm in glyceline at SDS concentrations as low as cSDS ∼ 0.1 wt%. The prevalence of these dendritic fractal aggregates led to the formation of a gel phase at SDS concentrations above ≥1.9 wt% (the critical gelation concentration cCGC). The gel microscopic structure was visualised using polarised light microscopy (PLM); rheology measurements confirmed the formation of a colloidal gel, where the first normal stress difference was negative and the elastic modulus was dominant. Detailed nano-structural characterisation by small-angle neutron scattering (SANS) further confirmed the presence of fractal aggregates. Such SDS aggregation or gelation has not been observed in water at such low surfactant concentrations, whereas SDS has been reported to form lamellar aggregates in glycerol (a component of glyceline). We attribute the formation of the SDS fractal dendrites to the condensation of counterions (i.e. the choline ions) around the SDS aggregates - a diffusion-controlled process, leading to the aggregate morphology observed. These unprecedented results shed light on the molecular mechanisms of surfactant self-assembly in deep eutectic solvents, important to their application in industrial formulation.
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Affiliation(s)
- Lauren Matthews
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK. and Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Silvia Ruscigno
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Sarah E Rogers
- ISIS Muon and Neutron Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, UK
| | - Paul Bartlett
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | | | - Robert Sochon
- GlaxoSmithKline, St George's Avenue, Weybridge, KT13 0DE, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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10
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Ishak MI, Dobryden I, Martin Claesson P, Briscoe WH, Su B. Friction at nanopillared polymer surfaces beyond Amontons' laws: Stick-slip amplitude coefficient (SSAC) and multiparametric nanotribological properties. J Colloid Interface Sci 2021; 583:414-424. [PMID: 33011410 DOI: 10.1016/j.jcis.2020.09.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/11/2020] [Accepted: 09/12/2020] [Indexed: 11/17/2022]
Abstract
Frictional and nanomechanical properties of nanostructured polymer surfaces are important to their technological and biomedical applications. In this work, poly(ethylene terephthalate) (PET) surfaces with a periodic distribution of well-defined nanopillars were fabricated through an anodization/embossing process. The apparent surface energy of the nanopillared surfaces was evaluated using the Fowkes acid-base approach, and the surface morphology was characterized using scanning electron microscope (SEM) and atomic force microscope (AFM). The normal and lateral forces between a silica microparticle and these surfaces were quantified using colloidal probe atomic force microscopy (CP-AFM). The friction-load relationship followed Amonton's first law, and the friction coefficient appeared to scale linearly with the nanopillar height. Furthermore, all the nanopillared surfaces showed pronounced frictional instabilities compared to the smooth sliding friction loop on the flat control. Performing the stick-slip amplitude coefficient (SSAC) analysis, we found a correlation between the frictional instabilities and the nanopillars density, pull-off force and work of adhesion. We have summarised the dependence of the nanotribological properties on such nanopillared surfaces on five relevant parameters, i.e. pull-off force fp, Amontons' friction coefficient μ, RMS roughness Rq, stick-slip amplitude friction coefficient SSAC, and work of adhesion between the substrate and water Wadh in a radar chart. Whilst demonstrating the complexity of the frictional behaviour of nanopillared polymer surfaces, our results show that analyses of multiparametric nanotribological properties of nanostructured surfaces should go beyond classic Amontons' laws, with the SSAC more representative of the frictional properties compared to the friction coefficient.
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Affiliation(s)
- Mohd I Ishak
- Bristol Dental School, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK; School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; Faculty of Engineering Technology, Universiti Malaysia Perlis (UniMAP), Perlis, Malaysia
| | - Illia Dobryden
- School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden; School of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden
| | - Per Martin Claesson
- School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Bo Su
- Bristol Dental School, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.
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11
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Bharatiya B, Wang G, Rogers SE, Pedersen JS, Mann S, Briscoe WH. Mixed liposomes containing gram-positive bacteria lipids: Lipoteichoic acid (LTA) induced structural changes. Colloids Surf B Biointerfaces 2021; 199:111551. [PMID: 33387794 DOI: 10.1016/j.colsurfb.2020.111551] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 11/26/2022]
Abstract
Lipoteichoic acid (LTA), a surface associated polymer amphiphile tethered directly to the Gram-positive bacterial cytoplasmic membrane, is a key structural and functional membrane component. Its composition in the membrane is regulated by bacteria under different physiological conditions. How such LTA compositional variations modulate the membrane structural stability and integrity is poorly understood. Here, we have investigated structural changes in mixed liposomes mimicking the lipid composition of Gram-positive bacteria membranes, in which the concentration of Bacillus Subtilis LTA was varied between 0-15 mol%. Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) measurements indicated formation of mixed unilamellar vesicles, presumably stabilized by the negatively charged LTA polyphosphates. The vesicle size increased with the LTA molar concentration up to ∼6.5 mol%, accompanied by a broadened size distribution, and further increasing the LTA concentration led to a decrease in the vesicle size. At 80 °C, SANS analyses showed the formation of larger vesicles with thinner shells. Complementary Cryo-TEM imaging confirmed the vesicle formation and the size increase with LTA addition, as well as the presence of interconnected spherical aggregates of smaller size at higher LTA concentrations. The results are discussed in light of the steric and electrostatic interactions of the bulky LTA molecules with increased chain fluidity at the higher temperature, which affect the molecular packing and interactions, and thus depend on the LTA composition, in the membrane.
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Affiliation(s)
- Bhavesh Bharatiya
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Gang Wang
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Sarah E Rogers
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, UK
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Building 1590-252, 8000, Aarhus C, Denmark
| | - Stephen Mann
- Max Planck Bristol Centre for Minimal Biology, Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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12
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Michel SES, Rogers SE, Briscoe WH, Galan MC. Tunable Thiol-Ene Photo-Cross-Linked Chitosan-Based Hydrogels for Biomedical Applications. ACS Appl Bio Mater 2020; 3:8075-8083. [PMID: 35019547 DOI: 10.1021/acsabm.0c01171] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Access to biocompatible hydrogels with tunable properties is of great interest in biomedical applications. Here we report the synthesis and characterization of a series of photo-cross-linked chitosan hydrogels from norbornene-functionalized chitosan (CS-nb) and various thiolated cross-linkers. The resulting materials were characterized by NMR, swelling ratio, rheology, SEM, and small angle neutron scattering (SANS) measurements. The hydrogels exhibited pH- and salt-dependent swelling, while the macro- and microscale properties could be modulated by the choice and degree of cross-linker or the polymer concentration. The materials could be molded in situ and loaded with small molecules that can be released overtime. Moreover, the incorporation of collagen in the hydrogels drastically improved cell adhesion, with excellent viabilities of human dermofibroblast cells on the hydrogels observed for up to 6 days, highlighting the potential use of these materials in the biomedical area.
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Affiliation(s)
- Sarah E S Michel
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Sarah E Rogers
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - M Carmen Galan
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
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13
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Michel SSE, Kilner A, Eloi JC, Rogers SE, Briscoe WH, Galan MC. Norbornene-Functionalized Chitosan Hydrogels and Microgels via Unprecedented Photoinitiated Self-Assembly for Potential Biomedical Applications. ACS Appl Bio Mater 2020; 3:5253-5262. [PMID: 35021700 DOI: 10.1021/acsabm.0c00629] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Access to biocompatible self-assembled gels and microgels is of great interests for a variety of biological applications from tissue engineering to drug delivery. Here, the facile synthesis of supramolecular hydrogels of norbornene (nb)-functionalized chitosan (CS-nb) via UV-triggered self-assembly in the presence of Irgacure 2959 (IRG) is reported. The in vitro stable hydrogels are injectable and showed pH-responsive swelling behavior, while their structure and mechanical properties could be tuned by tailoring the stereochemistry of the norbornene derivative (e.g., endo- or -exo). Interestingly, unlike other nb-type hydrogels, the gels possess nanopores within their structure, which might lead to potential drug delivery applications. A gelation mechanism was proposed based on hydrophobic interactions following the combination of IRG on norbornene, as supported by 1H NMR. This self-assembly mechanism was used to access microgels of size 100-150 nm, which could be further functionalized and showed no significant toxicity to human dermofibroblast cells.
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Affiliation(s)
- Sarah S E Michel
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS81TS, U.K
| | - Alice Kilner
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS81TS, U.K
| | - Jean-Charles Eloi
- Chemical Imaging Facility, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS81TS, U.K
| | - Sarah E Rogers
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS81TS, U.K
| | - M Carmen Galan
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS81TS, U.K
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14
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Matthews L, Przybyłowicz Ż, Rogers SE, Bartlett P, Johnson AJ, Sochon R, Briscoe WH. The curious case of SDS self-assembly in glycerol: Formation of a lamellar gel. J Colloid Interface Sci 2020; 572:384-395. [DOI: 10.1016/j.jcis.2020.03.102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/26/2020] [Accepted: 03/27/2020] [Indexed: 01/09/2023]
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15
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Wlodek M, Slastanova A, Fox LJ, Taylor N, Bikondoa O, Szuwarzynski M, Kolasinska-Sojka M, Warszynski P, Briscoe WH. Structural evolution of supported lipid bilayers intercalated with quantum dots. J Colloid Interface Sci 2020; 562:409-417. [PMID: 31806357 DOI: 10.1016/j.jcis.2019.11.102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/23/2019] [Accepted: 11/25/2019] [Indexed: 10/25/2022]
Abstract
HYPOTHESIS Supported lipid bilayers (SLBs) embedded with hydrophobic quantum dots (QDs) undergo temporal structural rearrangement. EXPERIMENTS Synchrotron X-ray reflectivity (XRR) was applied to monitor the temporal structural changes over a period of 24 h of mixed SLBs of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) / 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine (POPE) intercalated with 4.9 nm hydrophobic cadmium sulphide quantum dots (CdS QDs). The QD-embedded SLBs (QD-SLBs) were formed via rupture of the mixed liposomes on a positively charged polyethylene imine (PEI) monolayer. Atomic force microscopy (AFM) imaging provided complementary characterization of the bilayer morphology. FINDINGS Our results show time-dependent perturbations in the SLB structure due to the interaction upon QD incorporation. Compared to the SLB without QDs, at 3 h incubation time, there was a measurable decrease in the bilayer thickness and a concurrent increase in the scattering length density (SLD) of the QD-SLB. The QD-SLB then became progressively thicker with increasing incubation time, which - along with the fitted SLD profile - was attributed to the structural rearrangement due to the QDs being expelled from the inner leaflet to the outer leaflet of the bilayer. Our results give unprecedented mechanistic insights into the structural evolution of QD-SLBs on a polymer cushion, important to their potential biomedical and biosensing applications.
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Affiliation(s)
- Magdalena Wlodek
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Anna Slastanova
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Laura J Fox
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Nicholas Taylor
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Oier Bikondoa
- XMaS, The UK-CRG Beamline, The European Synchrotron (ESRF), 71 Avenue des Martyrs, 38043 Grenoble, France; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Michal Szuwarzynski
- AGH University of Science and Technology, Academic Centre for Materials and Nanotechnology, al. A. Mickiewicza 30, PL-30059 Krakow, Poland
| | - Marta Kolasinska-Sojka
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Piotr Warszynski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom.
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16
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Fox LJ, Matthews L, Stockdale H, Pichai S, Snow T, Richardson RM, Briscoe WH. Structural changes in lipid mesophases due to intercalation of dendritic polymer nanoparticles: Swollen lamellae, suppressed curvature, and augmented structural disorder. Acta Biomater 2020; 104:198-209. [PMID: 31904557 DOI: 10.1016/j.actbio.2019.12.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/21/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Abstract
Understanding interactions between nanoparticles and model membranes is relevant to functional nano-composites and the fundamentals of nanotoxicity. In this study, the effect of polyamidoamine (PAMAM) dendrimers as model nanoparticles (NP) on the mesophase behaviour of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) has been investigated using high-pressure small-angle X-ray scattering (HP-SAXS). The pressure-temperature (p-T) diagrams for POPE mesophases in excess water were obtained in the absence and presence of G2 and G4 polyamidoamine (PAMAM) dendrimers (29 Å and 45 Å in diameter, respectively) at varying NP-lipid number ratio (ν = 0.0002-0.02) over the pressure range p = 1-3000 bar and temperature range T = 20-80 °C. The p-T phase diagram of POPE exhibited the Lβ, Lα and HII phases. Complete analysis of the phase diagrams, including the relative area pervaded by different phases, phase transition temperatures (Tt) and pressures (pt), the lattice parameters (d-spacing), the pressure-dependence of d-spacing (Δd/Δp), and the structural ordering in the mesophase as gauged by the Scherrer coherence length (L) permitted insights into the size- and concentration-dependent interactions between the dendrimers and the model membrane system. The addition of dendrimers changed the phase transition pressure and temperature and resulted in the emergence of highly swollen lamellar phases, dubbed Lβ-den and Lα-den. G4 PAMAM dendrimers at the highest concentration ν = 0.02 suppressed the formation of the HII phase within the temperature range studied, whereas the addition of G2 PAMAM dendrimers at the same concentration promoted an extended mixed lamellar region in which Lα and Lβ phases coexisted. STATEMENT OF SIGNIFICANCE: Using high pressure small angle X-ray scattering in the pressure range 1-3000 bar and temperature range 20-60 °C, we have studied interactions between PAMAM dendrimers (as model nanoparticles) and POPE lipid mesophases (as model membranes). We report the pressure-temperature phase diagrams for the dendrimer-lipid mesophases for the first time. We find that the dendrimers alter the phase transition temperatures (Tt) and pressures (pt), the lattice parameters (d-spacing), and the structural order in the mesophase. We interpret these unprecedented results in terms of the fluidity of the lipid membranes and the interactions between the dendrimers and the membranes. Our findings are of fundamental relevance to the field of nanotoxicity and functional nanomaterials that integrate nanoparticles and organized lipid structures.
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17
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Redeker C, Briscoe WH. Interactions between Mutant Bacterial Lipopolysaccharide (LPS-Ra) Surface Layers: Surface Vesicles, Membrane Fusion, and Effect of Ca 2+and Temperature. Langmuir 2019; 35:15739-15750. [PMID: 31604373 DOI: 10.1021/acs.langmuir.9b02609] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipopolysaccharides (LPS) are a major component of the protective outer membrane of Gram-negative bacteria. Understanding how the solution conditions may affect LPS-containing membranes is important to optimizing the design of antibacterial agents (ABAs) which exploit electrostatic and hydrophobic interactions to disrupt the bacteria membrane. Here, interactions between surface layers of LPS (Ra mutants) in aqueous media have been studied using a surface force apparatus (SFA), exploring the effects of temperature and divalent Ca2+ cations. Complementary dynamic light scattering (DLS) characterization suggests that vesicle-like aggregates of diameter ∼28-80 nm are formed by LPS-Ra in aqueous media. SFA results show that LPS-Ra vesicles adsorb weakly onto mica in pure water at room temperature (RT) and the surface layers are readily squeezed out as the two surfaces approach each other. However, upon addition of calcium (Ca2+) cations at near physiological concentration (2.5 mM) at RT, LPS multilayers or deformed LPS liposomes on mica are observed, presumably due to bridging between LPS phosphate groups and between LPS phosphates and negatively charged mica mediated by Ca2+, with a hard wall repulsion at surface separation D0 ∼ 30-40 nm. At 40 °C, which is above the LPS-Ra β-α acyl chain melting temperature (Tm = 36 °C), fusion events between the surface layers under compression could be observed, evident from δD ∼ 8-10 nm steps in the force-distance profiles attributed to LPS-bilayers being squeezed out due to enhanced fluidity of the LPS acyl-chain, with a final hard wall surface separation D0 ∼ 8-10 nm corresponding to the thickness of a single bilayer confined between the surfaces. These unprecedented SFA results reveal intricate structural responses of LPS surface layers to temperature and Ca2+, with implications to our fundamental understanding of the structures and interactions of bacterial membranes.
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Affiliation(s)
- Christian Redeker
- School of Chemistry , University of Bristol , Cantock's Close, Bristol BS8 1TS , United Kingdom
| | - Wuge H Briscoe
- School of Chemistry , University of Bristol , Cantock's Close, Bristol BS8 1TS , United Kingdom
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18
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Fussell SL, Bayliss K, Coops C, Matthews L, Li W, Briscoe WH, Faers MA, Royall CP, van Duijneveldt JS. Reversible temperature-controlled gelation in mixtures of pNIPAM microgels and non-ionic polymer surfactant. Soft Matter 2019; 15:8578-8588. [PMID: 31642834 DOI: 10.1039/c9sm01299k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We investigate the reversible gelation of poly(N-isopropylacrylamide) (pNIPAM) microgels in the presence of triblock-copolymer (PEO-PPO-PEO type) surfactant. We demonstrate that the association of these polymers with the microgel particles at elevated temperature is responsible for the gelation, due to the temperature responsive nature of the components. This is highlighted by an increase in the apparent hydrodynamic diameter of the particles in dynamic light scattering experiments, which only occurs above the volume phase transition temperature of pNIPAM. The gels that result shrink over a time period much larger than that of the collapse of pNIPAM microgels, and retain the shape of the container they form in. We investigate the mechanism that leads to this gelation and the structure of the gels that result. Confocal microscopy experiments show that both polymers are present in the gel network, indicating that an associative mechanism is responsible for the gelation. We vary the pNIPAM particle architecture to further investigate the gelation process, and find that the cross-link distribution plays a key role in the gelation mechanism, where for uniformly cross-linked particles the gelation is not observed. This shows that the fuzzy corona of the pNIPAM microgels is involved in the association of the polymers, allowing the triblock-copolymer to penetrate the outer corona of the microgels and bridge the particles. The phase transition observed is close to physiological conditions, so these gels have the potential for use in biomedical applications, including tissue engineering.
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Affiliation(s)
- S L Fussell
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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19
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Michel SES, Dutertre F, Denbow ML, Galan MC, Briscoe WH. Facile Synthesis of Chitosan-Based Hydrogels and Microgels through Thiol–Ene Photoclick Cross-Linking. ACS Appl Bio Mater 2019; 2:3257-3268. [DOI: 10.1021/acsabm.9b00218] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Sarah E. S. Michel
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Fabien Dutertre
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Mark L. Denbow
- Fetal Medicine Unit, St Michael’s Hospital, Southwell Street, Bristol BS2 8EG, United Kingdom
| | - M. Carmen Galan
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Wuge H. Briscoe
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
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20
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Wąsik P, Seddon AM, Wu H, Briscoe WH. Bénard-Marangoni Dendrites upon Evaporation of a Reactive ZnO Nanofluid Droplet: Effect of Substrate Chemistry. Langmuir 2019; 35:5830-5840. [PMID: 30912950 DOI: 10.1021/acs.langmuir.9b00109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Evaporation of a particle laden sessile drop can lead to complex surface patterns with structural hierarchy. Most commonly, the dispersed particles are inert. We have recently reported that when the sessile drop contains reactive ZnO nanoparticles, solidified Bénard-Marangoni (BM) cells with dendritic micromorphology were formed in the residual surface pattern from in situ-generated nanoclusters. Here, we report the effect of substrate chemistry on the residual pattern from the evaporation of nanofluids containing ZnO particles dispersed in a mixture of cyclohexane and isobutylamine, by comparing three different substrates: glass, silicon, and hydrophilized silicon. In particular, we performed a quantitative analysis of the BM cell size, distribution, and the cell morphological characteristics via the fractal dimension analysis. We find that the size dimension λBM of the dendritic Bénard-Marangoni cells varied on the different substrates, attributed to their different hydrophilicity and affinity for water molecules, evident from the different polar components γP in their surface free energy from the Owens-Wendt analysis. The average BM cell size was the smallest for the glass substrate (λBM = 289 μm) and comparable for the unmodified and UV/ozone-treated silicon wafers (with λBM = 466 and 423 μm, respectively). The fractal dimension analysis provided a quantitative description of the BM cells with complex structural hierarchy, highlighting the differences in the geometric features of the surface patterns resulting from different substrate chemistry. We also found that the fractal dimensions depended on the BM cell size, attributing it to two different regimes: the growing fractals and the maturing fractals.
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Affiliation(s)
- Patryk Wąsik
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , U.K
| | | | - Hua Wu
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , U.K
| | - Wuge H Briscoe
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , U.K
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21
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Gobbo P, Patil AJ, Li M, Harniman R, Briscoe WH, Mann S. Programmed assembly of synthetic protocells into thermoresponsive prototissues. Nat Mater 2018; 17:1145-1153. [PMID: 30297813 DOI: 10.1038/s41563-018-0183-5] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 08/30/2018] [Indexed: 06/08/2023]
Abstract
Although several new types of synthetic cell-like entities are now available, their structural integration into spatially interlinked prototissues that communicate and display coordinated functions remains a considerable challenge. Here we describe the programmed assembly of synthetic prototissue constructs based on the bio-orthogonal adhesion of a spatially confined binary community of protein-polymer protocells, termed proteinosomes. The thermoresponsive properties of the interlinked proteinosomes are used collectively to generate prototissue spheroids capable of reversible contractions that can be enzymatically modulated and exploited for mechanochemical transduction. Overall, our methodology opens up a route to the fabrication of artificial tissue-like materials capable of collective behaviours, and addresses important emerging challenges in bottom-up synthetic biology and bioinspired engineering.
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Affiliation(s)
- Pierangelo Gobbo
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Avinash J Patil
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Mei Li
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Robert Harniman
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Wuge H Briscoe
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Stephen Mann
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK.
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22
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Wlodek M, Kolasinska-Sojka M, Szuwarzynski M, Kereïche S, Kovacik L, Zhou L, Islas L, Warszynski P, Briscoe WH. Supported lipid bilayers with encapsulated quantum dots (QDs) via liposome fusion: effect of QD size on bilayer formation and structure. Nanoscale 2018; 10:17965-17974. [PMID: 30226255 DOI: 10.1039/c8nr05877f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding interactions between functional nanoparticles and lipid bilayers is important to many emerging biomedical and bioanalytical applications. In this paper, we report incorporation of hydrophobic cadmium sulphide quantum dots (CdS QDs) into mixed 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) liposomes, and into their supported bilayers (SLBs). The QDs were found embedded in the hydrophobic regions of the liposomes and the supported bilayers, which retained the QD fluorescent properties. In particular, we studied the effect of the QD size (2.7-5.4 nm in diameter) on the formation kinetics and structure of the supported POPC/POPE bilayers, monitored in situ using quartz crystal microbalance with dissipation monitoring (QCM-D), as the liposomes ruptured onto the substrate. The morphology of the obtained QD-lipid hybrid bilayers was studied using atomic force microscopy (AFM), and their structure by synchrotron X-ray reflectivity (XRR). It was shown that the incorporation of hydrophobic QDs promoted bilayer formation on the PEI cushion, evident from the rupture and fusion of the QD-endowed liposomes at a lower surface coverage compared to the liposomes without QDs. Furthermore, the degree of disruption in the supported bilayer structure caused by the QDs was found to be correlated with the QD size. Our results provide mechanistic insights into the kinetics of the rupturing and formation process of QD-endowed supported lipid bilayers via liposome fusion on polymer cushions.
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Affiliation(s)
- Magdalena Wlodek
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
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Wąsik P, Redeker C, Dane TG, Seddon AM, Wu H, Briscoe WH. Hierarchical Surface Patterns upon Evaporation of a ZnO Nanofluid Droplet: Effect of Particle Morphology. Langmuir 2018; 34:1645-1654. [PMID: 29293357 DOI: 10.1021/acs.langmuir.7b03854] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Surface structures with tailored morphologies can be readily delivered by the evaporation-induced self-assembly process. It has been recently demonstrated that ZnO nanorods could undergo rapid chemical and morphological transformation into 3D complex structures of Zn(OH)2 nanofibers as a droplet of ZnO nanofluid dries on the substrate via a mechanism very different from that observed in the coffee ring effect. Here, we have investigated how the crystallinity and morphology of ZnO nanoparticles would affect the ultimate pattern formation. Three ZnO particles differing in size and shape were used, and their crystal structures were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Their dispersions were prepared by sonication in a mixture of isobutylamine and cyclohexane. Residual surface patterns were created by drop casting a droplet of the nanofluid on a silicon substrate. The residual surface patterns were analyzed by scanning electron microscopy (SEM) and microfocus grazing incidence X-ray diffraction (μGIXRD). Nanofluid droplets of the in-house synthesized ZnO nanoparticles resulted in residual surface patterns consisting of Zn(OH)2 nanofibers. However, when commercially acquired ZnO powders composed of crystals with various shapes and sizes were used as the starting material, Zn(OH)2 fibers were found covered by ZnO crystal residues that did not fully undergo the dissolution and recrystallization process during evaporation. The difference in the solubility of ZnO nanoparticles was linked to the difference in their crystallinity, as assessed using the Scherrer equation analysis of their XRD Bragg peaks. Our results show that the morphology of the ultimate residual pattern from evaporation of ZnO nanofluids can be controlled by varying the crystallinity of the starting ZnO nanoparticles which affects the nanoparticle dissolution process during evaporation.
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Affiliation(s)
- Patryk Wąsik
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K
| | - Christian Redeker
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K
| | - Thomas G Dane
- The European Synchrotron (ESRF) 71, Avenue des Martyrs, Grenoble, France
| | | | - Hua Wu
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K
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24
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Wlodek M, Kolasinska-Sojka M, Wasilewska M, Bikondoa O, Briscoe WH, Warszynski P. Interfacial and structural characteristics of polyelectrolyte multilayers used as cushions for supported lipid bilayers. Soft Matter 2017; 13:7848-7855. [PMID: 28976532 DOI: 10.1039/c7sm01645j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The surface properties of polyelectrolyte multilayers (PEMs) obtained via sequential adsorption of oppositely charged polyions from their solutions and used as cushions for supported lipid bilayers were investigated. Five types of polyelectrolytes were used: cationic polyethyleneimine (PEI), poly(diallyldimethylammonium)chloride (PDADMAC), and poly-l-lysine hydrobromide (PLL); and anionic polysodium 4-styrenesulfonate (PSS) and poly-l-glutamic acid sodium (PGA). The wettability and surface free energy of the PEMs were determined by contact angle measurements using sessile drop analysis. Electrokinetic characterisation of the studied films was performed by streaming potential measurements of selected multilayers and the structure of the polyelectrolyte multilayer was characterized by synchrotron X-ray reflectometry. The examined physicochemical properties of the PEMs were correlated with the kinetics of the formation of supported lipid bilayers atop the PEM cushion.
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Affiliation(s)
- M Wlodek
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow, Poland.
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Bartenstein JE, Liu X, Lange K, Claesson PM, Briscoe WH. Polymersomes at the solid-liquid interface: Dynamic morphological transformation and lubrication. J Colloid Interface Sci 2017; 512:260-271. [PMID: 29073467 DOI: 10.1016/j.jcis.2017.10.065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 10/18/2022]
Abstract
Polymersomes are hollow spheres self-assembled from amphiphilic block copolymers of certain molecular architecture. Whilst they have been widely studied for biomedical applications, relatively few studies have reported their interfacial properties. In particular, lubrication by polymersomes has not been previously reported. Here, interfacial properties of polymersomes self-assembled from poly(butadiene)-poly(ethylene oxide) (PBD-PEO; molecular weight 10,400 g mol-1) have been studied at both hydrophilic and hydrophobic surfaces. Their morphology at silica and mica surfaces was imaged with quantitative nanomechanical property mapping atomic force microscopy (QNM AFM), and friction and surface forces they mediate under confinement between two surfaces were studied using colloidal probe AFM (CP-AFM). We find that the polymersomes remained intact but adopted flattened conformation once adsorbed to mica, with a relatively low coverage. However, on silica these polymersomes were unstable, rupturing to form donut shaped residues or patchy bilayers. On a silica surface hydrophobized with a 19 nm polystyrene (PS) film, the polymer vesicles formed a more stable layer with a higher surface coverage as compared to the hydrophilic surface, and the interfacial structure also evolved over time. Moreover, friction was greatly reduced on hydrophobized silica surfaces in the presence of polymersomes, suggesting their potential as effective aqueous lubricants.
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Affiliation(s)
- Julia E Bartenstein
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Xiaoyan Liu
- Surface and Corrosion Science, Drottning Kristinas Väg 51, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Kathrin Lange
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Per M Claesson
- Surface and Corrosion Science, Drottning Kristinas Väg 51, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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26
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Tripathy A, Sen P, Su B, Briscoe WH. Natural and bioinspired nanostructured bactericidal surfaces. Adv Colloid Interface Sci 2017; 248:85-104. [PMID: 28780961 PMCID: PMC6643001 DOI: 10.1016/j.cis.2017.07.030] [Citation(s) in RCA: 248] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 07/25/2017] [Accepted: 07/25/2017] [Indexed: 01/22/2023]
Abstract
Bacterial antibiotic resistance is becoming more widespread due to excessive use of antibiotics in healthcare and agriculture. At the same time the development of new antibiotics has effectively ground to a hold. Chemical modifications of material surfaces have poor long-term performance in preventing bacterial build-up and hence approaches for realising bactericidal action through physical surface topography have become increasingly important in recent years. The complex nature of the bacteria cell wall interactions with nanostructured surfaces represents many challenges while the design of nanostructured bactericidal surfaces is considered. Here we present a brief overview of the bactericidal behaviour of naturally occurring and bio-inspired nanostructured surfaces against different bacteria through the physico-mechanical rupture of the cell wall. Many parameters affect this process including the size, shape, density, rigidity/flexibility and surface chemistry of the surface nanotextures as well as factors such as bacteria specificity (e.g. gram positive and gram negative) and motility. Different fabrication methods for such bactericidal nanostructured surfaces are summarised.
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Affiliation(s)
- Abinash Tripathy
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Prosenjit Sen
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Bo Su
- School of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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Bartenstein JE, Robertson J, Battaglia G, Briscoe WH. Stability of polymersomes prepared by size exclusion chromatography and extrusion. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.07.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Beddoes CM, Berge J, Bartenstein JE, Lange K, Smith AJ, Heenan RK, Briscoe WH. Hydrophilic nanoparticles stabilising mesophase curvature at low concentration but disrupting mesophase order at higher concentrations. Soft Matter 2016; 12:6049-6057. [PMID: 27340807 DOI: 10.1039/c6sm00393a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using high pressure small angle X-ray scattering (HP-SAXS), we have studied monoolein (MO) mesophases at 18 wt% hydration in the presence of 10 nm silica nanoparticles (NPs) at NP-lipid number ratios (ν) of 1 × 10(-6), 1 × 10(-5) and 1 × 10(-4) over the pressure range 1-2700 bar and temperature range 20-60 °C. In the absence of the silica NPs, the pressure-temperature (p-T) phase diagram of monoolein exhibited inverse bicontinuous cubic gyroid (Q), lamellar alpha (Lα), and lamellar crystalline (Lc) phases. The addition of the NPs significantly altered the p-T phase diagram, changing the pressure (p) and the temperature (T) at which the transitions between these mesophases occurred. In particular, a strong NP concentration effect on the mesophase behaviour was observed. At low NP concentration, the p-T region pervaded by the Q phase and the Lα-Q mixture increased, and we attribute this behaviour to the NPs forming clusters at the mesophase domain boundaries, encouraging transition to the mesophase with a higher curvature. At high NP concentrations, the Q phase was no longer observed in the p-T phase diagram. Instead, it was dominated by the lamellar (L) phases until the transition to a fluid isotropic (FI) phase at 60 °C at low pressure. We speculate that NPs formed aggregates with a "chain of pearls" structure at the mesophase domain boundaries, hindering transitions to the mesophases with higher curvatures. These observations were supported by small angle neutron scattering (SANS) and scanning electron microscopy (SEM). Our results have implications to nanocomposite materials and nanoparticle cellular entry where the interactions between NPs and organised lipid structures are an important consideration.
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Affiliation(s)
- Charlotte M Beddoes
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK. and Bristol Centre for Functional Nanomaterials, Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol BS8 1FD, UK
| | - Johanna Berge
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Julia E Bartenstein
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Kathrin Lange
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Andrew J Smith
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0QX, UK
| | | | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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Toolan DTW, Isakova A, Hodgkinson R, Reeves-McLaren N, Hammond OS, Edler KJ, Briscoe WH, Arnold T, Gough T, Topham PD, Howse JR. Insights into the Influence of Solvent Polarity on the Crystallization of Poly(ethylene oxide) Spin-Coated Thin Films via in Situ Grazing Incidence Wide-Angle X-ray Scattering. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00312] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniel T. W. Toolan
- Department
of Chemical and Biological Engineering, University of Sheffield, Sheffield. S1 3JD. U.K
| | - Anna Isakova
- Aston
Materials Centre, Aston University, Birmingham, B4 7ET, U.K
| | - Richard Hodgkinson
- Department
of Chemical and Biological Engineering, University of Sheffield, Sheffield. S1 3JD. U.K
| | - Nik Reeves-McLaren
- Department
of Materials Science and Engineering, University of Sheffield, Sheffield. S1 3JD. U.K
| | - Oliver S. Hammond
- Department
of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, U.K
| | - Karen J. Edler
- Department
of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, U.K
| | - Wuge H. Briscoe
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
| | - Thomas Arnold
- Diamond Light
Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
| | - Tim Gough
- School
of Engineering, University of Bradford, Bradford, BD7 1DP, U.K
| | - Paul D. Topham
- Aston
Materials Centre, Aston University, Birmingham, B4 7ET, U.K
| | - Jonathan R. Howse
- Department
of Chemical and Biological Engineering, University of Sheffield, Sheffield. S1 3JD. U.K
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31
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Beddoes CM, Whitehouse MR, Briscoe WH, Su B. Hydrogels as a Replacement Material for Damaged Articular Hyaline Cartilage. Materials (Basel) 2016; 9:E443. [PMID: 28773566 PMCID: PMC5456752 DOI: 10.3390/ma9060443] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 05/24/2016] [Accepted: 05/30/2016] [Indexed: 12/12/2022]
Abstract
Hyaline cartilage is a strong durable material that lubricates joint movement. Due to its avascular structure, cartilage has a poor self-healing ability, thus, a challenge in joint recovery. When severely damaged, cartilage may need to be replaced. However, currently we are unable to replicate the hyaline cartilage, and as such, alternative materials with considerably different properties are used. This results in undesirable side effects, including inadequate lubrication, wear debris, wear of the opposing articular cartilage, and weakening of the surrounding tissue. With the number of surgeries for cartilage repair increasing, a need for materials that can better mimic cartilage, and support the surrounding material in its typical function, is becoming evident. Here, we present a brief overview of the structure and properties of the hyaline cartilage and the current methods for cartilage repair. We then highlight some of the alternative materials under development as potential methods of repair; this is followed by an overview of the development of tough hydrogels. In particular, double network (DN) hydrogels are a promising replacement material, with continually improving physical properties. These hydrogels are coming closer to replicating the strength and toughness of the hyaline cartilage, while offering excellent lubrication. We conclude by highlighting several different methods of integrating replacement materials with the native joint to ensure stability and optimal behaviour.
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Affiliation(s)
- Charlotte M Beddoes
- School of Oral and Dental Sciences, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.
| | - Michael R Whitehouse
- Musculoskeletal Research Unit, University of Bristol, Level 1 Learning and Research Building, Bristol BS10 5NB, UK.
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Bo Su
- School of Oral and Dental Sciences, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.
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32
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Sironi B, Snow T, Redeker C, Slastanova A, Bikondoa O, Arnold T, Klein J, Briscoe WH. Structure of lipid multilayers via drop casting of aqueous liposome dispersions. Soft Matter 2016; 12:3877-3887. [PMID: 27009376 DOI: 10.1039/c6sm00369a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding the structure of solid supported lipid multilayers is crucial to their application as a platform for novel materials. Conventionally, they are prepared from drop casting or spin coating of lipids dissolved in organic solvents, and lipid multilayers prepared from aqueous media and their structural characterisation have not been reported previously, due to their extremely low lipid solubility (i.e.∼10(-9) M) in water. Herein, using X-ray reflectivity (XRR) facilitated by a "bending mica" method, we have studied the structural characteristics of dioleoylphosphatidylcholine (DOPC) multilayers prepared via drop casting aqueous small unilamellar and multilamellar vesicle or liposome (i.e. SUV and MLV) dispersions on different surfaces, including mica, positively charged polyethylenimine (PEI) coated mica, and stearic trimethylammonium iodide (STAI) coated mica which exposes a monolayer of hydrocarbon tails. We suggest that DOPC liposomes served both as a delivery matrix where an appreciable lipid concentration in water (∼25 mg mL(-1) or 14 mM) was feasible, and as a structural precursor where the lamellar structure was readily retained on the rupture of the vesicles at the solid surface upon solvent evaporation to facilitate rapid multilayer formation. We find that multilayers on mica from MLVs exhibited polymorphism, whereas the SUV multilayers were well ordered and showed stronger stability against water. The influence of substrate chemistry (i.e. polymer coating, charge and hydrophobicity) on the multilayer structure is discussed in terms of lipid-substrate molecular interactions determining the bilayer packing proximal to the solid-liquid interface, which then had a templating effect on the structure of the bilayers distal from the interface, resulting in the overall different multilayer structural characteristics on different substrates. Such a fundamental understanding of the correlation between the physical parameters that characterise liposomes and substrate chemistry, and the structure of lipid multilayers underpins the potential development of a simple method via an aqueous liposome dispersion route for the inclusion of hydrophilic functional additives (e.g. drugs or nanoparticles) into lipid multilayer based hybrid materials, where tailored structural characteristics are an important consideration.
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Affiliation(s)
- Beatrice Sironi
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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33
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Sharma KP, Harniman R, Farrugia T, Briscoe WH, Perriman AW, Mann S. Dynamic Behavior in Enzyme-Polymer Surfactant Hydrogel Films. Adv Mater 2016; 28:1597-1602. [PMID: 26676924 DOI: 10.1002/adma.201504740] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 10/15/2015] [Indexed: 06/05/2023]
Abstract
Dynamic protein-polymer surfactant films are highly hydrophilic and show a soft solid to hydrogel transition upon hydration to produce a swollen hydrogel. An unusual reversible autospreading/self-folding response is observed when the water-saturated films are transferred from water into air.
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Affiliation(s)
- Kamendra P Sharma
- Centre for Organized Matter Chemistry and Centre for Protolife Research, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Robert Harniman
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Thomas Farrugia
- Centre for Organized Matter Chemistry and Centre for Protolife Research, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Adam W Perriman
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Stephen Mann
- Centre for Organized Matter Chemistry and Centre for Protolife Research, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
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Dane TG, Bartenstein JE, Sironi B, Mills BM, Alexander Bell O, Emyr Macdonald J, Arnold T, Faul CFJ, Briscoe WH. Influence of solvent polarity on the structure of drop-cast electroactive tetra(aniline)-surfactant thin films. Phys Chem Chem Phys 2016; 18:24498-505. [DOI: 10.1039/c6cp05221e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure of drop-cast thin films of an electroactive oligomer–surfactant complex can be tuned through variation of solvent polarity.
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Affiliation(s)
- Thomas G. Dane
- School of Chemistry
- University of Bristol
- Bristol BS8 1TS
- UK
| | | | | | | | | | | | - Thomas Arnold
- Diamond Light Source Ltd
- Diamond House
- Harwell Science and Innovation Campus
- Didcot
- UK
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35
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Bulpett JM, Snow T, Quignon B, Beddoes CM, Tang TYD, Mann S, Shebanova O, Pizzey CL, Terrill NJ, Davis SA, Briscoe WH. Hydrophobic nanoparticles promote lamellar to inverted hexagonal transition in phospholipid mesophases. Soft Matter 2015; 11:8789-8800. [PMID: 26391613 DOI: 10.1039/c5sm01705j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This study focuses on how the mesophase transition behaviour of the phospholipid dioleoyl phosphatidylethanolamine (DOPE) is altered by the presence of 10 nm hydrophobic and 14 nm hydrophilic silica nanoparticles (NPs) at different concentrations. The lamellar to inverted hexagonal phase transition (Lα-HII) of phospholipids is energetically analogous to the membrane fusion process, therefore understanding the Lα-HII transition with nanoparticulate additives is relevant to how membrane fusion may be affected by these additives, in this case the silica NPs. The overriding observation is that the HII/Lα boundaries in the DOPE p-T phase diagram were shifted by the presence of NPs: the hydrophobic NPs enlarged the HII phase region and thus encouraged the inverted hexagonal (HII) phase to occur at lower temperatures, whilst hydrophilic NPs appeared to stabilise the Lα phase region. This effect was also NP-concentration dependent, with a more pronounced effect for higher concentration of the hydrophobic NPs, but the trend was less clear cut for the hydrophilic NPs. There was no evidence that the NPs were intercalated into the mesophases, and as such it was likely that they might have undergone microphase separation and resided at the mesophase domain boundaries. Whilst the loci and exact roles of the NPs invite further investigation, we tentatively discuss these results in terms of both the surface chemistry of the NPs and the effect of their curvature on the elastic bending energy considerations during the mesophase transition.
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Affiliation(s)
- Jennifer M Bulpett
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Tim Snow
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Benoit Quignon
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Charlotte M Beddoes
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - T-Y D Tang
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Stephen Mann
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Olga Shebanova
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Claire L Pizzey
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Nicholas J Terrill
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Sean A Davis
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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Beddoes CM, Case CP, Briscoe WH. Understanding nanoparticle cellular entry: A physicochemical perspective. Adv Colloid Interface Sci 2015; 218:48-68. [PMID: 25708746 DOI: 10.1016/j.cis.2015.01.007] [Citation(s) in RCA: 220] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 12/21/2022]
Abstract
Understanding interactions between nanoparticles (NPs) with biological matter, particularly cells, is becoming increasingly important due to their growing application in medicine and materials, and consequent biological and environmental exposure. For NPs to be utilised to their full potential, it is important to correlate their functional characteristics with their physical properties, which may also be used to predict any adverse cellular responses. A key mechanism for NPs to impart toxicity is to gain cellular entry directly. Many parameters affect the behaviour of nanomaterials in a cellular environment particularly their interactions with cell membranes, including their size, shape and surface chemistry as well as factors such as the cell type, location and external environment (e.g. other surrounding materials, temperature, pH and pressure). Aside from in vitro and in vivo experiments, model cell membrane systems have been used in both computer simulations and physicochemical experiments to elucidate the mechanisms for NP cellular entry. Here we present a brief overview of the effects of NPs physical parameters on their cellular uptake, with focuses on 1) related research using model membrane systems and physicochemical methodologies; and 2) proposed physical mechanisms for NP cellular entrance, with implications to their nanotoxicity. We conclude with a suggestion that the energetic process of NP cellular entry can be evaluated by studying the effects of NPs on lipid mesophase transitions, as the molecular deformations and thus the elastic energy cost are analogous between such transitions and endocytosis. This presents an opportunity for contributions to understanding nanotoxicity from a physicochemical perspective.
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Affiliation(s)
- Charlotte M Beddoes
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; Bristol Centre for Functional Nanomaterials, Centre for Nanoscience and Quantum Information, University of Bristol, UK
| | - C Patrick Case
- Musculoskeletal Research Unit, Clinical Science at North Bristol, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Bristol BS10 5NB, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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Pilkington GA, Pedersen JS, Briscoe WH. Dendrimer nanofluids in the concentrated regime: from polymer melts to soft spheres. Langmuir 2015; 31:3333-3342. [PMID: 25723405 DOI: 10.1021/la504870f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding dendrimer structures and their interactions in concentrated solutions is important to a wide range of applications, such as drug delivery and lubrication. However, controversy has persisted concerning whether, when confined to proximity, dendrimers would entangle as observed for polymer systems, or act as deformable spheres. Furthermore, how such behavior may be related to their size-dependent molecular architecture remains unclear. Using small-angle X-ray scattering (SAXS), the intermolecular interactions and structures in aqueous nanofluids containing three generations of carboxyl-terminated poly(amidoamine) (PAMAM) dendrimers (G0.5, Rg = 9.3 Å; G3.5, Rg = 22.6 Å; G5.5, Rg = 39.9 Å, where Rg is the radius of gyration) over a mass fraction range 0.005 ≤ x ≤ 0.316 have been studied. In the highly concentrated regime (x ≥ 0.157), we observe that the solution properties depend on the dendrimer generation. Our results suggest that the smaller G0.5 dendrimers form a highly entangled polymer melt, while the larger dendrimers, G3.5 and G5.5, form densely packed and ordered structures, in which the individual dendrimers exhibit some degree of mutual overlap or deformation. Our results demonstrate the tunability of interdendrimer interactions via their molecular architecture, which in turn may be harnessed to control and tailor the physical properties of dendrimer nanofluids.
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Affiliation(s)
- Georgia A Pilkington
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Jan S Pedersen
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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Wu H, Chen LX, Zeng XQ, Ren TH, Briscoe WH. Self-assembly in an evaporating nanofluid droplet: rapid transformation of nanorods into 3D fibre network structures. Soft Matter 2014; 10:5243-5248. [PMID: 24946161 DOI: 10.1039/c4sm00887a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Upon evaporation, ZnO nanorods in a nanofluid droplet undergo rapid and spontaneous chemical and morphological transformation into centimetre-long Zn(OH)2 fibres, via a mechanism very different from that for coffee rings. We show that the detailed nanostructure and micromorphology in the residual thin film depend intricately on the ambient moisture, nanofluid solvent composition and substrate surface chemistry. Upon thermal annealing, these Zn(OH)2 fibres readily undergo further chemical and morphological transformation, forming nanoporous fibres with the pore size tuneable by temperature. Our results point to a simple route for generating a self-assembled 3D structure with ultralong and nanoporous ZnO/Zn(OH)2 fibres/belts, and may also be of interest to the fields of evaporation controlled dynamic self-assembly, non-equilibrium crystallisation, and flow and fingering instabilities in nanofluids.
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Affiliation(s)
- H Wu
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China.
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Hansson PM, Claesson PM, Swerin A, Briscoe WH, Schoelkopf J, Gane PAC, Thormann E. Frictional forces between hydrophilic and hydrophobic particle coated nanostructured surfaces. Phys Chem Chem Phys 2014; 15:17893-902. [PMID: 24056733 DOI: 10.1039/c3cp52196f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Friction forces have long been associated with the famous Amontons' rule that states that the friction force is linearly dependent on the applied normal load, with the proportionality constant being known as the friction coefficient. Amontons' rule is however purely phenomenological and does not in itself provide any information on why the friction coefficient is different for different material combinations. In this study, friction forces between a colloidal probe and nanostructured particle coated surfaces in an aqueous environment exhibiting different roughness length scales were measured by utilizing the atomic force microscope (AFM). The chemistry of the surfaces and the probe was varied between hydrophilic silica and hydrophobized silica. For hydrophilic silica surfaces, the friction coefficient was significantly higher for the particle coated surfaces than on the flat reference surface. All the particle coated surfaces exhibited similar friction coefficients, from which it may be concluded that the surface geometry, and not the roughness amplitude per se, influenced the measured friction. During measurements with hydrophobic surfaces, strong adhesive forces related to the formation of a bridging air cavity were evident from both normal force and friction force measurements. In contrast to the frictional forces between the hydrophilic surfaces, the friction coefficient for hydrophobic surfaces was found to depend on the surface structure and we believe that this dependence is related to the restricted movement of the three-phase line of the bridging air cavity. For measurements using a hydrophobic surface and a hydrophilic probe, the friction coefficient was significantly smaller compared to the two homogeneous systems. A layer of air or air bubbles on the hydrophobic surface working as a lubricating layer is a possible mechanism behind this observation.
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Affiliation(s)
- Petra M Hansson
- SP Technical Research Institute of Sweden - Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden
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Quignon B, Pilkington GA, Thormann E, Claesson PM, Ashfold MNR, Mattia D, Leese H, Davis SA, Briscoe WH. Sustained frictional instabilities on nanodomed surfaces: stick-slip amplitude coefficient. ACS Nano 2013; 7:10850-10862. [PMID: 24219790 DOI: 10.1021/nn404276p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Understanding the frictional properties of nanostructured surfaces is important because of their increasing application in modern miniaturized devices. In this work, lateral force microscopy was used to study the frictional properties between an AFM nanotip and surfaces bearing well-defined nanodomes comprising densely packed prolate spheroids, of diameters ranging from tens to hundreds of nanometers. Our results show that the average lateral force varied linearly with applied load, as described by Amontons' first law of friction, although no direct correlation between the sample topographic properties and their measured friction coefficients was identified. Furthermore, all the nanodomed textures exhibited pronounced oscillations in the shear traces, similar to the classic stick-slip behavior, under all the shear velocities and load regimes studied. That is, the nanotextured topography led to sustained frictional instabilities, effectively with no contact frictional sliding. The amplitude of the stick-slip oscillations, σf, was found to correlate with the topographic properties of the surfaces and scale linearly with the applied load. In line with the friction coefficient, we define the slope of this linear plot as the stick-slip amplitude coefficient (SSAC). We suggest that such stick-slip behaviors are characteristics of surfaces with nanotextures and that such local frictional instabilities have important implications to surface damage and wear. We thus propose that the shear characteristics of the nanodomed surfaces cannot be fully described by the framework of Amontons' laws of friction and that additional parameters (e.g., σf and SSAC) are required, when their friction, lubrication, and wear properties are important considerations in related nanodevices.
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Affiliation(s)
- Benoit Quignon
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K
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Affiliation(s)
- Alexander G de Bruin
- Bristol Centre for Functional Nanomaterials; University of Bristol, Tyndall Avenue; Bristol BS8 1FD UK
- School of Chemistry; University of Bristol, Cantock's Close; Bristol BS8 1TS UK
| | - Michele E Barbour
- School of Oral and Dental Sciences; University of Bristol; Lower Maudlin Street Bristol BS1 2LY UK
| | - Wuge H Briscoe
- School of Chemistry; University of Bristol, Cantock's Close; Bristol BS8 1TS UK
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Pilkington GA, Briscoe WH. Nanofluids mediating surface forces. Adv Colloid Interface Sci 2012; 179-182:68-84. [PMID: 22795777 DOI: 10.1016/j.cis.2012.06.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 04/13/2012] [Accepted: 06/23/2012] [Indexed: 12/28/2022]
Abstract
Fluids containing nanostructures, known as nanofluids, are increasingly found in a wide array of applications due to their unique physical properties as compared with their base fluids and larger colloidal suspensions. With several tuneable parameters such as the size, shape and surface chemistry of nanostructures, as well as numerous base fluids available, nanofluids also offer a new paradigm for mediating surface forces. Other properties such as local surface plasmon resonance and size dependent magnetism of nanostructures also present novel mechanisms for imparting tuneable surface interactions. However, our fundamental understanding, experimentally and theoretically, of how these parameters might affect surface forces remains incomplete. Here we review recent results on equilibrium and dynamic surface forces between macroscopic surfaces in nanofluids, highlighting the overriding trends in the correlation between the physical parameters that characterise nanofluids and the surface forces they mediate. We also discuss the challenges that confront existing surface force knowledge as a result of this new paradigm.
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Bulpett JM, Collins AM, Kaus NHM, Cresswell PT, Bikondoa O, Walsh D, Mann S, Davis SA, Briscoe WH. Interactions of nanoparticles with purple membrane films. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32467a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pilkington GA, Thormann E, Claesson PM, Fuge GM, Fox OJL, Ashfold MNR, Leese H, Mattia D, Briscoe WH. Amontonian frictional behaviour of nanostructured surfaces. Phys Chem Chem Phys 2011; 13:9318-26. [DOI: 10.1039/c0cp02657c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Collins AM, Mohd Kaus NH, Speranza F, Briscoe WH, Rhinow D, Hampp N, Mann S. Assembly of poly(methacrylate)/purple membrane lamellar nanocomposite films by intercalation and in situ polymerisation. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm01358g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
The very low sliding friction at natural synovial joints, which have friction coefficients of mu < 0.002 at pressures up to 5 megapascals or more, has to date not been attained in any human-made joints or between model surfaces in aqueous environments. We found that surfaces in water bearing polyzwitterionic brushes that were polymerized directly from the surface can have mu values as low as 0.0004 at pressures as high as 7.5 megapascals. This extreme lubrication is attributed primarily to the strong hydration of the phosphorylcholine-like monomers that make up the robustly attached brushes, and may have relevance to a wide range of human-made aqueous lubrication situations.
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Affiliation(s)
- Meng Chen
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
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Dunlop IE, Briscoe WH, Titmuss S, Jacobs RMJ, Osborne VL, Edmondson S, Huck WTS, Klein J. Direct Measurement of Normal and Shear Forces between Surface-Grown Polyelectrolyte Layers. J Phys Chem B 2009; 113:3947-56. [DOI: 10.1021/jp807190z] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Iain E. Dunlop
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Wuge H. Briscoe
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Simon Titmuss
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Robert M. J. Jacobs
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Vicky L. Osborne
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Steve Edmondson
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Wilhelm T. S. Huck
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
| | - Jacob Klein
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, U.K., Melville Laboratory for Polymer Synthesis, University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, U.K., and Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
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Affiliation(s)
- Meng Chen
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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Chen M, Briscoe WH, Armes SP, Cohen H, Klein J. Cover Picture: Robust, Biomimetic Polymer Brush Layers Grown Directly from a Planar Mica Surface (ChemPhysChem 9/2007). Chemphyschem 2007. [DOI: 10.1002/cphc.200790025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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