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Sychev D, Schubotz S, Besford QA, Fery A, Auernhammer GK. Critical Analysis of Adhesion Work Measurements from AFM-based Techniques for Soft Contact. J Colloid Interface Sci 2023; 642:216-226. [PMID: 37004256 DOI: 10.1016/j.jcis.2023.03.139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 03/28/2023]
Abstract
HYPOTHESIS The work of adhesion is a thermodynamic quantity that is frequently measured by atomic force microscopy (AFM). Determination of the work of adhesion requires quasi-equilibrium measurements, where we address the question of to what extent atomic force microscopy qualifies for quasi-equilibrium measurements. EXPERIMENT To measure the work of adhesion, we combined soft colloidal probe AFM (SCP AFM) with reflection interference contrast microscopy (RICM). This allowed us to extract the work of adhesion either from the pull-off force or from the contact radius. With these methods, we investigated the adhesion behavior of poly(N-isopropylacrylamide) (PNIPAM) polymer brushes in the swollen and solvent-induced collapsed state by systematically analyzing contact radii and adhesive forces. FINDINGS In the swollen state, the adhesion to the PNIPAM brush was fivefold larger and exhibited significant time dependencies when measured with SCP AFM. A strong rate dependence of the pull-off force method was indicative of a non-equilibrium process. In order to reliably determine the equilibrium work of adhesion, the contact radius method was found to be the better because it is not rate dependent. Our work highlights the important benefits of using optical measurements to determine the contact radius when deriving the works of adhesion between colloidal probes and polymer brush surfaces.
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Petroli A, Petroli M, Romagnoli M, Geoghegan M. Determination of the rate-dependent adhesion of polydimethylsiloxane using an atomic force microscope. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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3
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Eskhan A, Johnson D. Microscale characterization of abiotic surfaces and prediction of their biofouling/anti-biofouling potential using the AFM colloidal probe technique. Adv Colloid Interface Sci 2022; 310:102796. [DOI: 10.1016/j.cis.2022.102796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 10/11/2022] [Accepted: 10/14/2022] [Indexed: 11/16/2022]
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4
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Jha A, Karnal P, Frechette J. Adhesion of fluid infused silicone elastomer to glass. SOFT MATTER 2022; 18:7579-7592. [PMID: 36165082 DOI: 10.1039/d2sm00875k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Elastomers swollen with non-polar fluids show potential as anti-adhesive materials. We study the effect of oil fraction and contact time on the adhesion between swollen spherical probes of PDMS (polydimethylsiloxane) and flat glass surfaces. The PDMS probes are swollen with pre-determined amount of 10 cSt silicone oil to span the range where the PDMS is fluid free (via solvent extraction) up to the limit where it is oil saturated. Probe tack measurements show that adhesion decreases rapidly with an increase in oil fraction. The decrease in adhesion is attributed to excess oil present at the PDMS-air interface. Contact angle measurements and optical microscopy images support this observation. Adhesion also increases with contact time for a given oil fraction. The increase in adhesion with contact time can be interpreted through different competing mechanisms that depend on the oil fraction where the dominant mechanism changes from extracted to fully swollen PDMS. For partially swollen PDMS, we observe that adhesion initially increases because of viscoelastic relaxation and at long times increases because of contact aging. In contrast, adhesion between fully swollen PDMS and glass barely increases over time and is mainly due to capillary forces. While the relaxation of PDMS in contact is well-described by a visco-poroelastic model, we do not see evidence that poroelastic relaxation of the PDMS contributes to an increase of adhesion with glass whether it is partially or fully swollen.
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Affiliation(s)
- Anushka Jha
- Chemical and Biomolecular Engineering Department, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Preetika Karnal
- Chemical and Biomolecular Engineering Department, Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Chemical and Biomolecular Engineering, Lehigh University, 124 E Morton St, Building 205, Bethlehem, Pennsylvania 18015, USA
| | - Joelle Frechette
- Chemical and Biomolecular Engineering Department, Johns Hopkins University, Baltimore, MD 21218, USA
- Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94760, USA.
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5
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Liamas E, Connell SD, Zembyla M, Ettelaie R, Sarkar A. Friction between soft contacts at nanoscale on uncoated and protein-coated surfaces. NANOSCALE 2021; 13:2350-2367. [PMID: 33367416 DOI: 10.1039/d0nr06527g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The understanding of friction on soft sliding biological surfaces at the nanoscale is poorly understood as hard interfaces are frequently used as model systems. Herein, we studied the influence of elastic modulus on the frictional properties of model surfaces at the nanoscale for the first time. We prepared model silicone-based elastomer surfaces with tuneable modulus ranging from hundreds of kPa to a few MPa, similar to those found in real biological surfaces, and employed atomic force microscopy to characterize their modulus, adhesion, and surface morphology. Consequently, we used friction force microscopy to investigate nanoscale friction in hard-soft and soft-soft contacts using spherical colloidal probes covered by adsorbed protein films. Unprecedented results from this study reveal that modulus of a surface can have a significant impact on the frictional properties of protein-coated surfaces with higher deformability leading to lower contact pressure and, consequently, decreased friction. These important results pave the way forward for designing new functional surfaces for serving as models of appropriate deformability to replicate the mechanical properties of the biological structures and processes for accurate friction measurements at nanoscale.
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Affiliation(s)
- Evangelos Liamas
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
| | - Simon D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, UK.
| | - Morfo Zembyla
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
| | - Rammile Ettelaie
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
| | - Anwesha Sarkar
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
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6
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Rettke D, Döring J, Martin S, Venus T, Estrela-Lopis I, Schmidt S, Ostermann K, Pompe T. Picomolar glyphosate sensitivity of an optical particle-based sensor utilizing biomimetic interaction principles. Biosens Bioelectron 2020; 165:112262. [PMID: 32510337 DOI: 10.1016/j.bios.2020.112262] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 01/18/2023]
Abstract
The continually growing use of glyphosate and its critically discussed health and biodiversity risks ask for fast, low cost, on-site sensing technologies for food and water. To address this problem, we designed a highly sensitive sensor built on the remarkably specific recognition of glyphosate by its physiological target enzyme 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPs). This principle is implemented in an interferometric sensor by using the recently established soft colloidal probe (SCP) technique. EPSPs was site-specifically immobilized on a transparent surface utilizing the self-assembling properties of circadian clock gene 2 hydrophobin chimera and homogeneity of the layer was evidenced by atomic force microscopy. Exposure of the enzyme decorated biochip to glyphosate containing samples causes formation of enzyme-analyte complexes and a competitive loss of available binding sites for glyphosate-functionalized poly(ethylene glycol) SCPs. Functionalization of the SCPs with different types of linker molecules and glyphosate was assessed employing confocal laser scanning microscopy as well as confocal Raman microspectroscopy. Overall, reflection interference contrast microscopy analysis of SCP-biochip interactions revealed a strong influence of linker length and glyphosate coupling position on the sensitivity of the sensor. In employing a combination of pentaglycine linker and tethering glyphosate via its secondary amino group, concentrations in aqueous solutions down to 100 pM could be measured by the differential adhesion between SCP and biochip surface, supported by automated image analysis algorithms. This sensing concept could even prove its exceptional pM sensitivity in combination with a superior discrimination against structurally related compounds.
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Affiliation(s)
- David Rettke
- Institute of Biochemistry, Leipzig University, Johannisallee 21-23, 04103, Leipzig, Germany
| | - Julia Döring
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217, Dresden, Germany
| | - Steve Martin
- Institute of Biochemistry, Leipzig University, Johannisallee 21-23, 04103, Leipzig, Germany
| | - Tom Venus
- Institute of Medical Physics and Biophysics, Leipzig University, Härtelstraße 16-18, 04107, Leipzig, Germany
| | - Irina Estrela-Lopis
- Institute of Medical Physics and Biophysics, Leipzig University, Härtelstraße 16-18, 04107, Leipzig, Germany
| | - Stephan Schmidt
- Institute of Organic Chemistry and Macromolecular Chemistry, Heinrich Heine Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Kai Ostermann
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217, Dresden, Germany
| | - Tilo Pompe
- Institute of Biochemistry, Leipzig University, Johannisallee 21-23, 04103, Leipzig, Germany.
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7
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Mark A, Helfricht N, Rauh A, Karg M, Papastavrou G. The Next Generation of Colloidal Probes: A Universal Approach for Soft and Ultra-Small Particles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1902976. [PMID: 31544313 DOI: 10.1002/smll.201902976] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 08/18/2019] [Indexed: 06/10/2023]
Abstract
The colloidal probe technique, which is based on the atomic force microscope, revolutionizes direct force measurements in many fields, such as interface science or biomechanics. It allows for the first time to determine interaction forces on the single particle or cell level. However, for many applications, important "blind spots" remain, namely, the possibility to probe interaction potentials for nanoparticles or complex colloids with a soft outer shell. Definitely, these are colloidal systems that are currently of major industrial importance and interest from theory. The here-presented novel approach allows for overcome the aforementioned limitations. Its applicability has been demonstrated for 300 nm sized carboxylate-modified latex particles as well as sub-micron core-shell particles with a soft poly-N-isopropylacrylamide hydrogel shell and a rigid silica core. For the latter, which until now cannot be studied by the colloidal probe technique, determined is the temperature dependency of electrosteric and adhesion forces has been determined on the single particle level.
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Affiliation(s)
- Andreas Mark
- Physical Chemistry II, University of Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Germany
| | - Nicolas Helfricht
- Physical Chemistry II, University of Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Germany
- Bavarian Polymer Institute, University of Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Germany
| | - Astrid Rauh
- Department of Physical Chemistry I, Heinrich-Heine-University, Universitätsstr. 1, 40204, Düsseldorf, Germany
| | - Matthias Karg
- Department of Physical Chemistry I, Heinrich-Heine-University, Universitätsstr. 1, 40204, Düsseldorf, Germany
| | - Georg Papastavrou
- Physical Chemistry II, University of Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Germany
- Bavarian Polymer Institute, University of Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Germany
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Gangotra A, Biviano M, Dagastine RR, Berry JD, Willmott GR. Use of microaspiration to study the mechanical properties of polymer gel microparticles. SOFT MATTER 2019; 15:7286-7294. [PMID: 31498362 DOI: 10.1039/c9sm00862d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The mechanical properties of polyacrylamide (PA) and polydimethylsiloxane (PDMS) microparticle populations have been measured using microaspiration, a recently developed experimental technique. Microaspiration is an augmented version of micropipette aspiration, in which optical microscopy data are obtained as individual soft particles pass through the tip of a micropipette. During microaspiration, the ion current passing through the pipette tip is also measured, and the synchronised optical and current data streams are used to study and quantify mechanical properties. Ion current signatures for the poroelastic PA particles were qualitatively different from those of the viscoelastic PDMS particles. For PA particles the current gradually reduced during each aspiration event, whereas for PDMS particles the current trace resembled a negative top hat function. For PA particles it was found that the maximum change in current during aspiration (ΔIh) increased with particle size. By considering the initial elastic response, a mean effective shear modulus (G') of 6.6 ± 0.2 kPa was found for aspiration of 115 PA particles of ∼10-20 μm diameter. Using a viscoelastic model to describe flow into the pipette, a mean initial effective elastic modulus (E0') of 3.5 ± 1.7 MPa was found for aspiration of 17 PDMS particles of ∼ 9-11 μm diameter. These moduli are consistent with previously reported literature values, providing initial validation of the microaspiration method.
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Affiliation(s)
- Ankita Gangotra
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand
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9
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Yamaguchi D. Measurement system for adhesion force on single particles with microelectromechanical-based actuated tweezers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:045003. [PMID: 31043053 DOI: 10.1063/1.5086910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 03/26/2019] [Indexed: 06/09/2023]
Abstract
A system for measuring the adhesion force of a single particle using microelectromechanical-system-based actuated tweezers (nanotweezers) and an atomic force microscope (AFM) cantilever was developed. In the proposed technique, a particle picked up with nanotweezers is brought into contact with and separated from the cantilever. The adhesion force is determined by measuring the deflection of the cantilever at the instant of separation from the particle. The throughput of measurement is much improved compared with that of a colloid probe AFM because the particle is picked up and held only by gripping with the nanotweezers, rather than sample preparation by manual cantilever mounting. A measurement apparatus was designed to realize the proposed system, and a force-displacement curve was successfully obtained. In addition, decreases in the adhesion force due to external coating added to particles were measured using the prototype apparatus.
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Affiliation(s)
- D Yamaguchi
- Ricoh Company Ltd., 2-7-1 Izumi, Ebina, Kanagawa 243-040, Japan
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10
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Buzio R, Gerbi A, Barra M, Chiarella F, Gnecco E, Cassinese A. Subnanometer Resolution and Enhanced Friction Contrast at the Surface of Perylene Diimide PDI8-CN 2 Thin Films in Ambient Conditions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3207-3214. [PMID: 29482328 DOI: 10.1021/acs.langmuir.7b04149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report high-resolution surface morphology and friction force maps of polycrystalline organic thin films derived by deposition of the n-type perylene diimide semiconductor PDI8-CN2. We show that the in-plane molecular arrangement into ordered, cofacial slip-stacked rows results in a largely anisotropic surface structure, with a characteristic sawtooth corrugation of a few Ångstroms wavelength and height. Load-controlled experiments reveal different types of friction contrast between the alternating sloped and stepped regions, with transitions from atomic-scale dissipative stick-slip to smooth sliding with ultralow friction within the surface unit cell. Notably, such a rich phenomenology is captured under ambient conditions. We demonstrate that friction contrast is well reproduced by numerical simulations assuming a reduced corrugation of the tip-molecule potential nearby the step edges. We propose that the side alkyl chains pack into a compact low-surface-energy overlayer, and friction modulation reflects periodic heterogeneity of chains bending properties and subsurface anchoring to the perylene cores.
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Affiliation(s)
- Renato Buzio
- CNR-SPIN Institute for Superconductors, Innovative Materials, and Devices, C.so Perrone 24 , 16152 Genova , Italy
| | - Andrea Gerbi
- CNR-SPIN Institute for Superconductors, Innovative Materials, and Devices, C.so Perrone 24 , 16152 Genova , Italy
| | - Mario Barra
- CNR-SPIN and Physics Department , University of Naples Federico II , Piazzale Tecchio , 80125 Napoli , Italy
| | - Fabio Chiarella
- CNR-SPIN and Physics Department , University of Naples Federico II , Piazzale Tecchio , 80125 Napoli , Italy
| | - Enrico Gnecco
- Otto Schott Institute of Materials Research , Friedrich Schiller University Jena , Löbdergraben 32 , 07743 Jena , Germany
| | - Antonio Cassinese
- CNR-SPIN and Physics Department , University of Naples Federico II , Piazzale Tecchio , 80125 Napoli , Italy
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11
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Buzio R, Gerbi A, Uttiya S, Bernini C, Del Rio Castillo AE, Palazon F, Siri AS, Pellegrini V, Pellegrino L, Bonaccorso F. Ultralow friction of ink-jet printed graphene flakes. NANOSCALE 2017; 9:7612-7624. [PMID: 28540370 DOI: 10.1039/c7nr00625j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the frictional response of few-layer graphene (FLG) flakes obtained by the liquid phase exfoliation (LPE) of pristine graphite. To this end, we inkjet print FLG on bare and hexamethyldisilazane-terminated SiO2 substrates, producing micrometric patterns with nanoscopic roughness that are investigated by atomic force microscopy. Normal force spectroscopy and atomically-resolved morphologies indicate reduced surface contamination by solvents after a vacuum annealing process. Notably, the printed FLG flakes show ultralow friction comparable to that of micromechanically exfoliated graphene flakes. Lubricity is retained on flakes with a lateral size of a few tens of nanometres, and with a thickness as small as ∼2 nm, confirming the high crystalline quality and low defects density in the FLG basal plane. Surface exposed step edges exhibit the highest friction values, representing the preferential sites for the origin of the secondary dissipative processes related to edge straining, wear or lateral displacement of the flakes. Our work demonstrates that LPE enables fundamental studies on graphene friction to the single-flake level. The capability to deliver ultralow-friction-graphene over technologically relevant substrates, using a scalable production route and a high-throughput, large-area printing technique, may also open up new opportunities in the lubrication of micro- and nano-electromechanical systems.
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Affiliation(s)
- R Buzio
- CNR-SPIN Institute for Superconductors, Innovative Materials and Devices, C.so Perrone 24, I-16152 Genova, Italy
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12
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Helfricht N, Doblhofer E, Bieber V, Lommes P, Sieber V, Scheibel T, Papastavrou G. Probing the adhesion properties of alginate hydrogels: a new approach towards the preparation of soft colloidal probes for direct force measurements. SOFT MATTER 2017; 13:578-589. [PMID: 27976776 DOI: 10.1039/c6sm02326f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The adhesion of alginate hydrogels to solid surfaces was probed by atomic force microscopy (AFM) in the sphere/plane geometry. For this purpose a novel approach has been developed for the immobilization of soft colloidal probes onto AFM-cantilevers, which is inspired by techniques originating from cell biology. The aspiration and consecutive manipulation of hydrogel beads by micropipettes allows the entire manipulation sequence to be carried-out in situ. Hence, any alteration of the hydrogel beads upon drying can be excluded. The adhesive behaviour of alginate hydrogels was first evaluated by determining the distribution of pull-off forces on self-assembled monolayers (SAMs) terminating in different functional groups (-CH3, -OH, -NH2, -COOH). It was demonstrated that solvent exclusion plays practically no role in the adhesion process, in clear difference to solid colloidal probes. The adhesion of alginate beads is dominated by chemical interactions rather than solvent exclusion, in particular in the case of amino-terminated SAMs. The data set acquired on the SAMs provided the framework to relate the adhesion of alginate beads on recombinant spider silk protein films to specific functional groups. The preparation of soft colloidal probes and the presented approach in analysing the adhesive behaviour is not limited to alginate hydrogel beads but can be generally applied for probing and understanding the adhesion behaviour of hydrogels on a wide range of substrates, which would be relevant for various applications such as biomedical surface modification or tissue engineering.
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Affiliation(s)
- Nicolas Helfricht
- Physical Chemistry/Physics of Polymers, University of Bayreuth, Universitätsstr. 30, Bayreuth 95440, Germany.
| | - Elena Doblhofer
- Biomaterials, University of Bayreuth, Universitätsstr. 30, Bayreuth 95440, Germany
| | - Vera Bieber
- Physical Chemistry/Physics of Polymers, University of Bayreuth, Universitätsstr. 30, Bayreuth 95440, Germany.
| | - Petra Lommes
- Chemistry of Biogenic Resources, Technical University Munich, Schulgasse 16, 94315 Straubing, Germany
| | - Volker Sieber
- Chemistry of Biogenic Resources, Technical University Munich, Schulgasse 16, 94315 Straubing, Germany
| | - Thomas Scheibel
- Biomaterials, University of Bayreuth, Universitätsstr. 30, Bayreuth 95440, Germany
| | - Georg Papastavrou
- Physical Chemistry/Physics of Polymers, University of Bayreuth, Universitätsstr. 30, Bayreuth 95440, Germany.
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Martin S, Wang H, Rathke T, Anderegg U, Möller S, Schnabelrauch M, Pompe T, Schmidt S. Polymer hydrogel particles as biocompatible AFM probes to study CD44/hyaluronic acid interactions on cells. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.02.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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14
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Application of the Johnson–Kendall–Roberts model in AFM-based mechanical measurements on cells and gel. Colloids Surf B Biointerfaces 2015; 134:131-9. [DOI: 10.1016/j.colsurfb.2015.06.044] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/02/2015] [Accepted: 06/22/2015] [Indexed: 11/17/2022]
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15
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Rankin JM, Neelakantan NK, Lundberg KE, Grzincic EM, Murphy CJ, Suslick KS. Magnetic, Fluorescent, and Copolymeric Silicone Microspheres. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2015; 2:1500114. [PMID: 27980956 PMCID: PMC5115411 DOI: 10.1002/advs.201500114] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Indexed: 05/30/2023]
Abstract
Silicone microspheres are exceedingly difficult to make. Here, polydimethylsiloxane microspheres (≈1 μm diameter) are synthesized using ultrasonic spray pyrolysis, the first demonstration of a scalable synthetic procedure for crosslinked silicone microspheres. This continuous, aerosol process is also used to directly produce fluorescent, magnetic, and copolymeric derivatives; the potential biomedical applications of these microspheres are explored.
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Affiliation(s)
- Jacqueline M Rankin
- Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Matthews Ave Urbana IL 61801 USA
| | - Nitin K Neelakantan
- Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Matthews Ave Urbana IL 61801 USA
| | - Kimberly E Lundberg
- Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Matthews Ave Urbana IL 61801 USA
| | - Elissa M Grzincic
- Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Matthews Ave Urbana IL 61801 USA
| | - Catherine J Murphy
- Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Matthews Ave Urbana IL 61801 USA
| | - Kenneth S Suslick
- Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Matthews Ave Urbana IL 61801 USA
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16
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Pussak D, Ponader D, Mosca S, Pompe T, Hartmann L, Schmidt S. Specific adhesion of carbohydrate hydrogel particles in competition with multivalent inhibitors evaluated by AFM. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6142-6150. [PMID: 24806833 DOI: 10.1021/la5010006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Synthetic glycooligomers have emerged as valuable analogues for multivalent glycan structures in nature. These multivalent carbohydrates bind to specific receptors and play a key role in biological processes. In this work, we investigate the specific interaction between mannose ligand presenting soft colloidal probes (SCPs) attached to an atomic force microscope (AFM) cantilever and a Concanavalin A (ConA) receptor surface in the presence of competing glycooligomer ligands. We studied the SCP-ConA adhesion energy via the JKR approach and AFM pull-off experiments in combination with optical microscopy allowing for simultaneous determination of the contact area between SCP and ConA surface. We varied the contact time, loading rate and loading force and measured the resulting mannose/ConA interaction. The average adhesion energy per mannose ligand on the probe was 5 kJ/mol, suggesting that a fraction of mannose ligands presented on the SCP bound to the receptor surface. Adhesion measurements via competitive binding of the SCP in the presence of multivalent glycooligomer ligands did not indicate an influence of their multivalency on the glycooligomer displacement from the ConA surface. The absence of this "multivalency effect" indicates that glycooligomers and ConA do not associate via chelate complexes and shows that steric shielding by the glycooligomers does not slow their displacement upon competitive binding of a ligand presenting surface. These results highlight the high reversibility of carbohydrate-surface interactions, which could be an essential feature of recognition processes on the cell surface.
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Affiliation(s)
- Daniel Pussak
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Wissenschaftspark Potsdam-Golm, Am Mühlenberg 1 OT Golm, 14426 Potsdam, Germany
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17
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Schmidt S, Reinecke A, Wojcik F, Pussak D, Hartmann L, Harrington MJ. Metal-Mediated Molecular Self-Healing in Histidine-Rich Mussel Peptides. Biomacromolecules 2014; 15:1644-52. [DOI: 10.1021/bm500017u] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephan Schmidt
- Departments of ‡Biomaterials and §Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Antje Reinecke
- Departments of ‡Biomaterials and §Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Felix Wojcik
- Departments of ‡Biomaterials and §Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Daniel Pussak
- Departments of ‡Biomaterials and §Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Laura Hartmann
- Departments of ‡Biomaterials and §Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Matthew James Harrington
- Departments of ‡Biomaterials and §Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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Keller A, Fritzsche M, Ogaki R, Bald I, Facsko S, Dong M, Kingshott P, Besenbacher F. Tuning the hydrophobicity of mica surfaces by hyperthermal Ar ion irradiation. J Chem Phys 2012; 134:104705. [PMID: 21405182 DOI: 10.1063/1.3561292] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The hydrophobicity of surfaces has a strong influence on their interactions with biomolecules such as proteins. Therefore, for in vitro studies of bio-surface interactions model surfaces with tailored hydrophobicity are of utmost importance. Here, we present a method for tuning the hydrophobicity of atomically flat mica surfaces by hyperthermal Ar ion irradiation. Due to the sub-100 eV energies, only negligible roughening of the surface is observed at low ion fluences and also the chemical composition of the mica crystal remains almost undisturbed. However, the ion irradiation induces the preferential removal of the outermost layer of K(+) ions from the surface, leading to the exposure of the underlying aluminosilicate sheets which feature a large number of centers for C adsorption. The irradiated surface thus exhibits an enhanced chemical reactivity toward hydrocarbons, resulting in the adsorption of a thin hydrocarbon film from the environment. Aging these surfaces under ambient conditions leads to a continuous increase of their contact angle until a fully hydrophobic surface with a contact angle >80° is obtained after a period of about 3 months. This method thus enables the fabrication of ultrasmooth biological model surfaces with precisely tailored hydrophobicity.
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Affiliation(s)
- Adrian Keller
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C, Denmark.
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Zhou H, Peukert W. Modeling adhesion forces between deformable bodies by FEM and Hamaker summation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:1459-1468. [PMID: 18179262 DOI: 10.1021/la7023023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A new numerical approach is presented for predicting adhesion forces of particles at flat and rough surfaces. The new hybrid method uses the finite element method (FEM) for the determination of elastic and plastic particle deformation combined with numerical Hamaker summation. In the numerical approach, the influence of the plastic deformation can be fully included. We show how the adhesion force depends on the contact geometry and the material properties. For easy comparison with other models, the force-displacement behavior of the systems is presented. The numerical approach is supported by atomic force microscopy (AFM) measurements. The experimentally observed adhesion force hysteresis is described very well by the new approach. Although calculations in this article are focused on spherical particles, our approach can be extended to particles of arbitrary shapes.
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Affiliation(s)
- Hongben Zhou
- Institute of Particle Technology, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Bavaria, Germany
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