1
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Pickett PD, Ma Y, Prabhu VM. Polyzwitterion fast and slow mode behavior are coupled to phase separation as observed by dynamic laser light scattering. J Chem Phys 2023; 159:104902. [PMID: 37694748 DOI: 10.1063/5.0162376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/18/2023] [Indexed: 09/12/2023] Open
Abstract
A model zwitterionic polysulfobetaine, poly(3-(acrylamidopropyl-dimethyl-ammonium) propyl-1-sulfonate) (pAPAPS), phase separates upon cooling and exhibits an upper critical solution temperature (UCST) behavior with no added salt in deuterium oxide solutions. Dynamic light scattering measurements indicate the presence of distinct fast and slow diffusive modes, where the fast mode is interpreted as a collective diffusion coefficient and the slow mode is attributed to the diffusion of multi-chain dynamic clusters. The relative population of fast and slow modes varies systematically with temperature and concentration. A clustering temperature (T*) was assigned when the slow mode first appeared upon cooling. The slow mode then increases in relative scattering amplitude as the phase boundary is approached. The fast mode exhibits a concentration dependence above T* consistent with the virial expansion in the collective diffusion. The sign of the virial coefficient (kd) is negative, even in the good solvent region above the expected Flory temperature (Θ ≈ 39 °C), a behavior distinct from synthetic neutral polymers in organic solvents. The onset of multi-chain clustering at T < T* coincides with the poor solvent regime (T < Θ). Attractive dipolar interactions due to the zwitterionic sulfobetaine groups in pAPAPS are suggested as the origin of the multi-chain clusters with no salt. Upon the addition of 100 mM NaCl, the slow mode is suppressed, and the hydrodynamic radius is consistent with polyzwitterion chain dimensions in a dilute solution. We find that concentration dependent diffusion is highly linked to the theta temperature and the emergence of dynamic clusters as the polymer goes from good to poor solvent on approach to the UCST. The slow mode in the semidilute regime is reported along with preliminary small-angle neutron scattering data that show salt reduces clustering and leads to predominantly chain scattering.
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Affiliation(s)
- Phillip D Pickett
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Yuanchi Ma
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Vivek M Prabhu
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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2
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Quantification of shunt fraction using contrast ultrasound and indicator dilution in an in vitro model. Respir Physiol Neurobiol 2023; 310:104013. [PMID: 36639005 DOI: 10.1016/j.resp.2023.104013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/12/2023]
Abstract
Transthoracic saline contrast echocardiography is commonly used to assess intrathoracic shunt flow in vivo. Though the technique has many advantages (safe, simple, repeatable), the measurement technique lacks specificity, and the contrast agent has limited stability. This study sought to determine if the indicator dilution modeling technique could be applied to ultrasound contrast data to quantify shunt fraction and to determine if buoyant force has a significant effect on microbubble pathway determination at a "vascular" bifurcation. A model of the pulmonary circuit was perfused with blood at three distinct flow rates (low, medium and high) over shunt fractions ranging from ∼2-10 %. The buoyancy effect on contrast was quantified using a simplified in vitro model of a vascular bifurcation that had an upper and lower outflow tract where saline contrast formed from carbon monoxide (CO) gas passed through the bifurcation, was collected and quantified. The indicator dilution model was found to have a mean bias of - 3.2 % for the low flow stage, - 2.6 % for the medium flow stage and - 1.4 % for the high flow stage compared to volumetric measurements, suggesting agreement increases with increasing flow rate. Investigations of the buoyant effects revealed that at lower flow rates, contrast bubbles that encounter a bifurcation will favor the upper outflow tract over the lower. However, this effect is reduced by increasing the flow rate two-fold. These data identify that application of indicator dilution theory to contrast ultrasound data and the pathway ultrasound contrast travels in a network of tubules is flow dependent.
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3
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Gajevic Joksimovic M, Schmidt JB, Roisman IV, Tropea C, Hussong J. Impact of a suspension drop onto a hot substrate: diminution of splash and prevention of film boiling. SOFT MATTER 2023; 19:1440-1453. [PMID: 36723248 DOI: 10.1039/d2sm01038k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In the present study, the effect of graphite lubricant additives on the dynamics of a single drop impact onto a heated surface has been investigated in the nucleate boiling and thermal atomization regimes. In the nucleate boiling regime the drop impact is accompanied by the nucleation and expansion of multiple vapor bubbles. The drop residence time at the substrate is determined by the time of its mass loss due to splash and evaporation. At higher temperatures, above the Leidenfrost point, impact may lead to drop rebound. In this experimental and theoretical study the effect of additives on the outcome of drop impact, in particular, the addition of solid graphite particles, is investigated. The residence time of the drop has been measured for various initial drop temperatures and suspension concentrations. The addition of the particles leads to some increase of the residence time, while its dependence on the substrate temperature follows the scaling relation obtained in the theory. Moreover, the presence of the particles in the drop leads to suppression of splash and a significant increase of the drop rebound temperature, which is often associated with the Leidenfrost point. These effects are caused by the properties of the deposited layer, and pinning of the contact line of the entire drop and of each vapor bubble, preventing bubble coalescence and drop rebound. The phenomena are also explained by a significant increase of the liquid viscosity caused by the evaporation of the bulk liquid at high wall temperatures.
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Affiliation(s)
- Marija Gajevic Joksimovic
- Institute for Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - J Benedikt Schmidt
- Institute for Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Ilia V Roisman
- Institute for Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Cameron Tropea
- Institute for Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Jeanette Hussong
- Institute for Fluid Mechanics and Aerodynamics, Technische Universität Darmstadt, Darmstadt, Germany.
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4
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Katashima T, Kobayashi R, Ishikawa S, Naito M, Miyata K, Chung UI, Sakai T. Decoupling between Translational Diffusion and Viscoelasticity in Transient Networks with Controlled Network Connectivity. Gels 2022; 8:gels8120830. [PMID: 36547354 PMCID: PMC9778075 DOI: 10.3390/gels8120830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
The mobility of sustained molecules is influenced by viscoelasticity, which is strongly correlated with the diffusional property in polymeric liquid. However, the study of transient networks formed by a reversible crosslink, which is the viscoelastic liquid, was insufficient due to the absence of a model system. We compare the viscoelastic and diffusional properties of the transient networks, using the model system with controlled network connectivity (Tetra-PEG slime). According to independent measurements of viscoelasticity and diffusion, the root-mean-square distance the polymer diffuses during the viscoelastic relaxation time shows a large deviation from the self-size of the polymer, which is contrary to the conventional understanding. This decoupling between viscoelasticity and diffusion is unique for transient networks, suggesting that the viscoelastic relaxation is not induced by the diffusion of one prepolymer, particularly in the network with low connectivity. These findings will provide a definite basis for discussion to understand the viscoelasticity in transient networks.
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Affiliation(s)
- Takuya Katashima
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Correspondence: ; Tel.: +81-3-(5841)-1873
| | - Ryunosuke Kobayashi
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shohei Ishikawa
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Mitsuru Naito
- Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kanjiro Miyata
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Ung-il Chung
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takamasa Sakai
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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5
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Dou X, Huang H, Wang X, Lin Q, Li J, Zhang Y, Han Y. Collision Dependent Silver Nucleation Regulated by Chemical Diffusion and Reaction. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.117965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Laber JR, Laue TM, Filoti DI. Use of Debye-Hückel-Henry charge measurements in early antibody development elucidates effects of non-specific association. Antib Ther 2022; 5:211-215. [PMID: 35983303 PMCID: PMC9380711 DOI: 10.1093/abt/tbac018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 06/21/2022] [Accepted: 07/10/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
The diffusion interaction parameter (kD) has been demonstrated to be a high-throughput technique for characterizing interactions between proteins in solution. kD reflects both attractive and repulsive interactions, including long-ranged electrostatic repulsions. Here, we plot the mutual diffusion coefficient (Dm) as a function of the experimentally determined Debye-Hückel-Henry surface charge (ZDHH) for seven human monoclonal antibodies (mAbs) in 15 mM histidine, pH 6. We find that graphs of Dm versus ZDHH intersect at ZDHH, ~ 2.6, independent of protein concentration. The same data plotted as kD vs. ZDHH shows a transition from net attractive to net repulsive interactions in the same region of the ZDHH intersection point. These data suggest that there is a minimum surface charge necessary on these mAbs needed to overcome attractive interactions.
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Affiliation(s)
- Joshua R Laber
- Formulation and Biologics Product Development, Nektar Therapeutics , 455 Mission Bay Boulevard South, San Francisco, CA 94158, USA
| | - Thomas M Laue
- Carpenter Professor Emeritus, University of New Hampshire , Durham, NH 03824, USA
| | - Dana I Filoti
- Analytical Research and Development, AbbVie , 100 Research Drive, Worcester, MA 01605, USA
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7
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Deou J, Bessaies-Bey H, Declercq F, Smith P, Debon S, Wallecan J, Roussel N. Decrease of the amount of fat in chocolate at constant viscosity by optimizing the particle size distribution of chocolate. FOOD STRUCTURE 2022. [DOI: 10.1016/j.foostr.2022.100253] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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8
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Judy E, Lopus M, Kishore N. Mechanistic insights into encapsulation and release of drugs in colloidal niosomal systems: biophysical aspects. RSC Adv 2021; 11:35110-35126. [PMID: 35493162 PMCID: PMC9042874 DOI: 10.1039/d1ra06057k] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/21/2021] [Indexed: 12/24/2022] Open
Abstract
Vesicular systems such as niosomes provide an alternative to improve drug delivery systems. The efficiency of a drug delivery vehicle is strongly dependent on its components which decide its interaction with partitioned drug(s) and locus of site of partitioning. A quantitative understanding of the physical chemistry underlying partitioning of drugs in complex systems of self-assemblies such as niosomes is scarcely available. In order to obtain quantitative mechanistic insights into partitioning and release of drugs [mitoxantrone (MTX) and ketoprofen (KTP)] in systems of niosomes, we have employed ultrasensitive calorimetry, spectroscopy and microscopy to establish correlations between functionality and energetics which could provide guidance towards rational drug design and choice of suitable non-ionic surfactant-based drug delivery vehicles. Electron microscopy and dynamic light scattering (DLS) methods were used for characterization and assessing the morphology of niosomes. We present here a calorimetry-based approach in assessing the partitioning of the anticancer drugs mitoxantrone and ketoprofen in niosomes and their release to human serum albumin (HSA) employing isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) and comparison with equilibrium dialysis. The thermodynamic signatures and kinetics of release were analyzed to obtain insights into the role of the functional groups on the drugs in the partitioning process. The assessment of thermal and conformational stability of proteins during drug binding and the effect of drug delivery vehicles on proteins is also crucial. To assess these effects, DSC studies on HSA in the presence and absence of drugs and niosomes were also performed. Finally, the efficacy of the system to impact the cell viability of the MDA-MB-231 triple-negative breast carcinoma cell line was analysed using MTT assay. Vesicular systems such as niosomes provide an alternative to improve drug delivery systems.![]()
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Affiliation(s)
- Eva Judy
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400 076 India
| | - Manu Lopus
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai Vidyanagari Mumbai 400 098 India
| | - Nand Kishore
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400 076 India
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9
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Ti YT, Cheng HC, Li Y, Tu HL. Multiplexed patterning of hybrid lipid membrane and protein arrays for cell signaling study. LAB ON A CHIP 2021; 21:2711-2720. [PMID: 34109339 DOI: 10.1039/d1lc00178g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The supported lipid bilayer (SLB) is a powerful tool for studying dynamic cell-environment interactions and has been widely used for biosensing applications. Using a reusable microfluidic chip, we present here a strategy to fabricate highly multiplexed SLB and protein arrays for cell signaling research. This approach allows for the rapid patterning of hundreds of highly reproducible and size-tunable SLB arrays with distinct lipid composition and mobility. Using fluorescence microscopy and fluorescence correlation spectroscopy, the lipid mobility is found to play a central role for patterning this membrane assay. Adding protein rings as diffusion barriers extends the accessible mobility range and maintains long-term stability of the hybrid array. Subsequent protein functionalizations on the SLB could be conducted using standard conjugation methods. The utility of the hybrid array for cell signaling experiments is demonstrated by studying the immune NF-κB signaling, whose activity is triggered by the binding of the membrane receptor, toll-like-receptor 4 (TLR 4), to its ligand, lipopolysaccharide (LPS), that is functionalized on the SLB. The patterned array allows cells to adhere and spread on areas without LPS before migrating to interact with membrane-bound LPS to initiate NF-κB activation. Overall, the strategy offers an efficient route to rapidly generate easily controllable and multiplexed molecular arrays that can serve as versatile platforms for biosensing and cell signaling research.
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Affiliation(s)
- Yu-Ting Ti
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan. and Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Hsiao-Chi Cheng
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
| | - Ying Li
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
| | - Hsiung-Lin Tu
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan. and Genome and Systems Biology Degree Program, Academia Sinica and National Taiwan University, Taiwan
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10
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Chong WH, Leong SS, Lim J. Design and operation of magnetophoretic systems at microscale: Device and particle approaches. Electrophoresis 2021; 42:2303-2328. [PMID: 34213767 DOI: 10.1002/elps.202100081] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 06/13/2021] [Accepted: 06/24/2021] [Indexed: 12/11/2022]
Abstract
Combining both device and particle designs are the essential concepts to be considered in magnetophoretic system development. Researcher efforts are often dedicated to only one of these design aspects and neglecting the interplay between them. Herein, to bring out importance of the idea of integration between device and particle, we reviewed the working principle of magnetophoretic system (includes both device and particle design concepts). Since, the magnetophoretic force is influenced by both field gradient and magnetization volume, hence, accurate prediction of the magnetophoretic force is relying on the availability of information on both parameters. In device design, we focus on the different strategies used to create localized high-field gradient. For particle design, we emphasize on the scaling between hydrodynamic size and magnetization volume. Moreover, we also briefly discussed the importance of magnetoshape anisotropy related to particle design aspect of magnetophoretic systems. Next, we illustrated the need for integration between device and particle design using microscale applications of magnetophoretic systems, include magnetic tweezers and microfluidic systems, as our working example. On the basis of our discussion, we highlighted several promising examples of microscale magnetophoretic systems which greatly utilized the interplay between device and particle design. Further, we concluded the review with several factors that possibly resulted in the lack of research efforts related to device and particle design integration.
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Affiliation(s)
- Wai Hong Chong
- School of Chemical Engineering, Universiti Sains Malaysia, Penang, Malaysia
| | - Sim Siong Leong
- Department of Petrochemical Engineering, Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Kampar, Perak, Malaysia
| | - JitKang Lim
- School of Chemical Engineering, Universiti Sains Malaysia, Penang, Malaysia.,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
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11
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Dauer K, Kamm W, Wagner KG, Pfeiffer-Marek S. High-Throughput Screening for Colloidal Stability of Peptide Formulations Using Dynamic and Static Light Scattering. Mol Pharm 2021; 18:1939-1955. [PMID: 33789055 DOI: 10.1021/acs.molpharmaceut.0c01028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Selection of an appropriate formulation to stabilize therapeutic proteins against aggregation is one of the most challenging tasks in early-stage drug product development. The amount of aggregates is more difficult to quantify in the case of peptides due to their small molecular size. Here, we investigated the suitability of diffusion self-interaction parameters (kD) and osmotic second virial coefficients (B22) for high-throughput (HT) screening of peptide formulations regarding their aggregation risk. These parameters were compared to the effect of thermal stress on colloidal stability. The formulation matrix comprised six buffering systems at two selected pH values, four tonicity agents, and a common preservative. The results revealed that electrostatic interactions are the main driver to control colloidal stability. Preferred formulations consisted of acetate and succinate buffer at pH 4.5 combined with glycerol or mannitol and optional m-cresol. kD proved to be a suitable surrogate for B22 as an indicator of high colloidal stability in the case of peptides as was previously described for globular proteins and antibodies. Formulation assessment solely based on kD obtained by HT methods offers important insights into the optimization of colloidal stability during the early development of peptide-based liquid formulations and can be performed with a limited amount of peptide (∼360 mg).
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Affiliation(s)
- Katharina Dauer
- Department of Pharmaceutical Technology and Biopharmaceutics, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Str. 3, 53121 Bonn, Germany.,Pharmaceutical Development Platform, Tides Drug Product Pre-Development Sciences, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, 65926 Frankfurt am Main, Germany
| | - Walter Kamm
- Pharmaceutical Development Platform, Tides Drug Product Pre-Development Sciences, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, 65926 Frankfurt am Main, Germany
| | - Karl Gerhard Wagner
- Department of Pharmaceutical Technology and Biopharmaceutics, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Str. 3, 53121 Bonn, Germany
| | - Stefania Pfeiffer-Marek
- Pharmaceutical Development Platform, Tides Drug Product Pre-Development Sciences, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, 65926 Frankfurt am Main, Germany
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12
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Pathak JA, Nugent S, Bender MF, Roberts CJ, Curtis RJ, Douglas JF. Comparison of Huggins Coefficients and Osmotic Second Virial Coefficients of Buffered Solutions of Monoclonal Antibodies. Polymers (Basel) 2021; 13:601. [PMID: 33671342 PMCID: PMC7922252 DOI: 10.3390/polym13040601] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/12/2021] [Accepted: 02/14/2021] [Indexed: 01/08/2023] Open
Abstract
The Huggins coefficient kH is a well-known metric for quantifying the increase in solution viscosity arising from intermolecular interactions in relatively dilute macromolecular solutions, and there has been much interest in this solution property in connection with developing improved antibody therapeutics. While numerous kH measurements have been reported for select monoclonal antibodies (mAbs) solutions, there has been limited study of kH in terms of the fundamental molecular interactions that determine this property. In this paper, we compare measurements of the osmotic second virial coefficient B22, a common metric of intermolecular and interparticle interaction strength, to measurements of kH for model antibody solutions. This comparison is motivated by the seminal work of Russel for hard sphere particles having a short-range "sticky" interparticle interaction, and we also compare our data with known results for uncharged flexible polymers having variable excluded volume interactions because proteins are polypeptide chains. Our observations indicate that neither the adhesive hard sphere model, a common colloidal model of globular proteins, nor the familiar uncharged flexible polymer model, an excellent model of intrinsically disordered proteins, describes the dependence of kH of these antibodies on B22. Clearly, an improved understanding of protein and ion solvation by water as well as dipole-dipole and charge-dipole effects is required to understand the significance of kH from the standpoint of fundamental protein-protein interactions. Despite shortcomings in our theoretical understanding of kH for antibody solutions, this quantity provides a useful practical measure of the strength of interprotein interactions at elevated protein concentrations that is of direct significance for the development of antibody formulations that minimize the solution viscosity.
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Affiliation(s)
- Jai A. Pathak
- Vaccine Production Program (VPP), Vaccine Research Center (VRC), Formulation and Stabilization Sciences Department, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), 9 W. Watkins Mill Rd., Gaithersburg, MD 20878, USA; (J.A.P.); (S.N.); (M.B.)
| | - Sean Nugent
- Vaccine Production Program (VPP), Vaccine Research Center (VRC), Formulation and Stabilization Sciences Department, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), 9 W. Watkins Mill Rd., Gaithersburg, MD 20878, USA; (J.A.P.); (S.N.); (M.B.)
| | - Michael F. Bender
- Vaccine Production Program (VPP), Vaccine Research Center (VRC), Formulation and Stabilization Sciences Department, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), 9 W. Watkins Mill Rd., Gaithersburg, MD 20878, USA; (J.A.P.); (S.N.); (M.B.)
| | - Christopher J. Roberts
- Colburn Laboratory, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA;
| | - Robin J. Curtis
- Department of Chemical Engineering and Analytical Science, University of Manchester, Oxford Road, Manchester M13 9PL, UK;
| | - Jack F. Douglas
- Materials Science and Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8544, USA
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13
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Li G, Varga I, Kardos A, Dobryden I, Claesson PM. Temperature-Dependent Nanomechanical Properties of Adsorbed Poly-NIPAm Microgel Particles Immersed in Water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1902-1912. [PMID: 33502872 PMCID: PMC7879429 DOI: 10.1021/acs.langmuir.0c03386] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/15/2021] [Indexed: 05/24/2023]
Abstract
The temperature dependence of nanomechanical properties of adsorbed poly-NIPAm microgel particles prepared by a semibatch polymerization process was investigated in an aqueous environment via indentation-based atomic force microscopy (AFM) methods. Poly-NIPAm microgel particles prepared by the classical batch process were also characterized for comparison. The local mechanical properties were measured between 26 and 35 °C, i.e., in the temperature range of the volume transition. Two different AFM tips with different shapes and end radii were utilized. The nanomechanical properties measured by the two kinds of tips showed a similar temperature dependence of the nanomechanical properties, but the actual values were found to depend on the size of the tip. The results suggest that the semibatch synthesis process results in the formation of more homogeneous microgel particles than the classical batch method. The methodological approach reported in this work is generally applicable to soft surface characterization in situ.
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Affiliation(s)
- Gen Li
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
| | - Imre Varga
- Institute
of Chemistry, Eötvös Loránd
University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
- Department
of Chemistry, University J. Selyeho, 945 01 Komarno, Slovakia
| | - Attila Kardos
- Institute
of Chemistry, Eötvös Loránd
University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
- Department
of Chemistry, University J. Selyeho, 945 01 Komarno, Slovakia
| | - Illia Dobryden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
- Department
of Engineering Sciences and Mathematics, Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden
| | - Per M. Claesson
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
- Division
of Bioscience and Materials, RISE Research
Institutes of Sweden, Box 5607, SE 114 86 Stockholm, Sweden
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14
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Boulet LM, Vermeulen TD, Cotton PD, Foster GE. Influence of blood Po 2 on the stability of agitated saline contrast. J Appl Physiol (1985) 2020; 129:1341-1347. [PMID: 33054656 DOI: 10.1152/japplphysiol.00488.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The utility of transthoracic saline contrast echocardiography (TTSCE) to assess blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) in humans is limited due to the potential destabilizing effects of the gas concentration gradients established in varied blood-gas environments. This study assessed the specific effect of a hyperoxic and mixed venous blood-gas environment on the stability of saline contrast. We hypothesized that the rate of contrast mass lost in hyperoxic blood would be similar to mixed venous due to the establishment of equal and opposing gas gradients (O2, N2, CO2) created when the partial pressure of dissolved gases is manipulated. Using an in vitro model of the pulmonary circulation perfused with defibrinated sheep blood and a membrane oxygenator to control blood gases, we assessed the percent contrast conserved (an index of contrast stability) between inflow and outflow sites at multiple flow rates (1.8, 2.8, 4.3, and 6.8 L/min) in a hyperoxic (Po2: 646 ± 16 mmHg; Pco2: 0 ± 0 mmHg) and a mixed venous blood gas condition (Po2: 35 ± 3 mmHg; Pco2: 40 ± 0 mmHg). We found significant contrast decay with time in both conditions, with slightly higher contrast conservation in the hyperoxia trials (64 ± 32%) versus the mixed venous trials (55 ± 21%). These findings suggest that contrast stability is not likely a factor affecting the interpretation of TTSCE performed in healthy humans breathing hyperoxia and lends support to the existence of a local O2-dependent mechanism contributing to the regulation of Q̇IPAVA.NEW & NOTEWORTHY Hyperoxic blood has a small stabilizing effect on agitated saline contrast compared with mixed venous blood, lending support to studies that show the reversal of exercise-induced blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) with hyperoxia. These data support the possible presence of a local O2-dependent regulatory mechanism within the pulmonary vasculature that may play a role in Q̇IPAVA regulation.
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Affiliation(s)
- Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paul D Cotton
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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15
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Developing Rapid Antimicrobial Susceptibility Testing for Motile/Non-Motile Bacteria Treated with Antibiotics Covering Five Bactericidal Mechanisms on the Basis of Bead-Based Optical Diffusometry. BIOSENSORS-BASEL 2020; 10:bios10110181. [PMID: 33228090 PMCID: PMC7699397 DOI: 10.3390/bios10110181] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022]
Abstract
Rapid antimicrobial susceptibility testing (AST) is an effective measure in the treatment of infections and the prevention of bacterial drug resistance. However, diverse antibiotic types and bacterial characteristics have formed complicated barriers to rapid diagnosis. To counteract these limitations, we investigated the interactions between antibiotic-treated bacteria and functionalized microbeads in optical diffusometry. The conjugation with bacteria increased the effective microbead complex size, thereby resulting in a temporal diffusivity change. The yielded data were sorted and analyzed to delineate a pattern for the prediction of antimicrobial susceptibility. The outcome showed that a completed rapid AST based on the trend of microbead diffusivity could provide results within 3 h (2 h measurement + 1 h computation). In this research, we studied four bacterial strains, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus, and six antibiotics. Despite the different inhibitory effects caused by various antibiotics, similar trends in diffusivity alteration for all susceptible and resistant cases in the last 40 min of the 2-h measurement period were deduced. In addition, the AST results obtained using optical diffusometry showed good agreement with those acquired from the commercial instrument and conventional culture methods. Finally, we conducted a single-blinded clinical test, and the sensitivity, specificity, and accuracy of the system reached 92.9%, 91.4%, and 91.8%, respectively. Overall, the developed optical diffusometry showcased rapid AST with a small sample volume (20 μL) and low initial bacterial count (105 CFU/mL). This technique provided a promising way to achieve early therapy against microbial diseases in the future.
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16
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Sousa NG, Salgueira JF, Sousa CP, Campos OS, Salazar-Banda GR, Eguiluz KIB, de Lima-Neto P, Correia AN. Silver electrodeposition at room temperature protic ionic liquid 1-H-methylimidazolium hydrogen sulfate. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Singh A, Khatun S, Gupta AN. Anisotropy versus fluctuations in the fractal self-assembly of gold nanoparticles. SOFT MATTER 2020; 16:7778-7788. [PMID: 32744550 DOI: 10.1039/d0sm00485e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In a recent report, the fractal self-assembly of gold nanoparticles (AuNPs) having a directional feature was observed in the presence of visible light. Therein, the visible light, an external parameter, was suspected to be responsible for the directional feature. Herein, we investigate the intrinsic factors, the aspect size ratio p and the size a of AuNPs, in modulating the fractal characteristics of their self-assemblies. Through light scattering experiments and microscopic imaging, we demonstrate the transition of morphologies from fractal-like to cross-shaped in gold colloidal aggregates with particles having nearly spherical and ellipsoidal shapes, respectively. The transition indicates the competitive role of anisotropy and fluctuations in deciding the morphological characteristics of the aggregates. By taking noise-reduced diffusion-limited aggregation (NRDLA) as a model system, we address the shape and size induced noise of the particles in the colloidal systems which are prone to form fractal aggregates. We qualitatively relate the noise due to the particles having a distinct aspect size ratio p and size a with the noise reduction parameter m of NRDLA. The realistic nature of the experimental systems, where the particles of different p and a are present during the growth process, is incorporated by introducing the Gaussian noise reduction in diffusion-limited aggregation (DLA). The morphological phase transition in Gaussian noise reduced DLA is characterized, and its relevance for accounting the shape and size originated noise fluctuations during the fractal growth process is discussed. The results of the present study may be used for tailored applications of AuNPs in drug delivery, biomedicine, biosensing, and cancer nanotechnology.
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Affiliation(s)
- Anurag Singh
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology, Kharagpur-721302, India.
| | - Suparna Khatun
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology, Kharagpur-721302, India.
| | - Amar Nath Gupta
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology, Kharagpur-721302, India.
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18
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Cluster-Related Phenomena in the Properties and Transformations of Transition Metal-Based Glassy Alloys. METALS 2020. [DOI: 10.3390/met10081025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A survey of the cluster formation tendency and mechanism in transition metal-based glassy alloys is made with an emphasis on their manifestation in various physical properties. The cluster formation is partially inherited from the supercooling of the melt. However, it also develops due to the interaction between dissolved hydrogen and the frozen glassy structure. The glassy state as “cluster assembly” is regarded as a structural background for the interpretation of several anomalous concentration dependences of thermal and magnetic properties in these glasses. We will focus on the manifestation of alloying effects, the relation between irreversible and reversible structural relaxations both in the high, and low temperature range (observed near to the glass transition or after low temperature storage). The development of the cluster assembly is the consequence of the co-existence of various bonding types between the alloy components. These are brought together in the melt, ensuring sufficient glass-forming ability. The nucleation mechanism of the amorphous-nanocrystalline transformation is also explained as a cluster phenomenon, which significantly contributes to the evolution of magnetic ultra-softness in FINEMET-type alloys. Finally, the role of the quenched-in cluster structure in the mechanism of reversible and irreversible H-absorption is discussed. Irreversible H-induced structural rearrangements can appear as microphase separation in multicomponent systems, governed by the affinity difference between the metallic components and the absorbed hydrogen. This kind of H-induced reordering is responsible for the “volume activation” of amorphous H-storage alloys and it also causes the gradual breakdown of storage capacity during cyclic absorption–desorption steps. This article mainly focuses on the cluster phenomena in Fe-based glasses because of its unique combination of high mechanical strength, strong corrosion resistance, good thermal stability and excellent magnetic properties.
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Nanocellulose for Stabilization of Pickering Emulsions and Delivery of Nutraceuticals and Its Interfacial Adsorption Mechanism. FOOD BIOPROCESS TECH 2020. [DOI: 10.1007/s11947-020-02481-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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20
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Peña JS, Vazquez M. VEGF Upregulates EGFR Expression to Stimulate Chemotactic Behaviors in the rMC-1 Model of Müller Glia. Brain Sci 2020; 10:E330. [PMID: 32485834 PMCID: PMC7348795 DOI: 10.3390/brainsci10060330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/28/2020] [Accepted: 05/27/2020] [Indexed: 12/14/2022] Open
Abstract
Progressive vision loss in adults has become increasingly prevalent worldwide due to retinopathies associated with aging, genetics, and epigenetic factors that damage the retinal microvasculature. Insufficient supply of oxygen and/or nutrients upregulates factors such as vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF), which can induce abnormal angiogenesis and damage the structural arrangement of the retinal blood barrier (BRB). Müller glia (MG) regulate the diffusion of essential compounds across the BRB and respond to retinal insults via reactive gliosis, which includes cell hypertrophy, migration, and/or proliferation near areas of elevated VEGF concentration. Increasing concentrations of exogenous VEGF, upregulated by retinal pigmented epithelium cells, and endogenous epidermal growth factor receptor (EGF-R) stimulation in MG, implicated in MG proliferative and migratory behavior, often lead to progressive and permanent vision loss. Our project examined the chemotactic responses of the rMC-1 cell line, a mammalian MG model, toward VEGF and EGF signaling fields in transwell assays, and within respective concentration gradient fields produced in the glia line (gLL) microfluidic system previously described by our group. rMC-1 receptor expression in defined ligand fields was also evaluated using quantitative polymerase chain reaction (qPCR) and immunocytochemical staining. Results illustrate dramatic increases in rMC-1 chemotactic responses towards EGF gradient fields after pre-treatment with VEGF. In addition, qPCR illustrated significant upregulation of EGF-R upon VEGF pre-treatment, which was higher than that induced by its cognate ligand, EGF. These results suggest interplay of molecular pathways between VEGF and EGF-R that have remained understudied in MG but are significant to the development of effective anti-VEGF treatments needed for a variety of retinopathies.
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Affiliation(s)
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA;
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21
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Shen C, Jiang Z, Li L, Gilchrist JF, Ou-Yang HD. Frequency Response of Induced-Charge Electrophoretic Metallic Janus Particles. MICROMACHINES 2020; 11:mi11030334. [PMID: 32213879 PMCID: PMC7142510 DOI: 10.3390/mi11030334] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 03/19/2020] [Accepted: 03/21/2020] [Indexed: 12/23/2022]
Abstract
The ability to manipulate and control active microparticles is essential for designing microrobots for applications. This paper describes the use of electric and magnetic fields to control the direction and speed of induced-charge electrophoresis (ICEP) driven metallic Janus microrobots. A direct current (DC) magnetic field applied in the direction perpendicular to the electric field maintains the linear movement of particles in a 2D plane. Phoretic force spectroscopy (PFS), a phase-sensitive detection method to detect the motions of phoretic particles, is used to characterize the frequency-dependent phoretic mobility and drag coefficient of the phoretic force. When the electric field is scanned over a frequency range of 1 kHz-1 MHz, the Janus particles exhibit an ICEP direction reversal at a crossover frequency at ~30 kH., Below this crossover frequency, the particle moves in a direction towards the dielectric side of the particle, and above this frequency, the particle moves towards the metallic side. The ICEP phoretic drag coefficient measured by PFS is found to be similar to that of the Stokes drag. Further investigation is required to study microscopic interpretations of the frequency at which ICEP mobility switched signs and the reason why the magnitudes of the forward and reversed modes of ICEP are so different.
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Affiliation(s)
- Chong Shen
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
| | - Zhiyu Jiang
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
| | - Lanfang Li
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
| | - James F. Gilchrist
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA;
| | - H. Daniel Ou-Yang
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
- Department of Bioengineering, Lehigh University, Bethlehem, PA 18015, USA
- Correspondence:
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22
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Basak S, Sengupta S, Chattopadhyay K. Understanding biochemical processes in the presence of sub-diffusive behavior of biomolecules in solution and living cells. Biophys Rev 2019; 11:851-872. [PMID: 31444739 PMCID: PMC6957588 DOI: 10.1007/s12551-019-00580-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 07/25/2019] [Indexed: 01/24/2023] Open
Abstract
In order to maintain cellular function, biomolecules like protein, DNA, and RNAs have to diffuse to the target spaces within the cell. Changes in the cytosolic microenvironment or in the nucleus during the fulfillment of these cellular processes affect their mobility, folding, and stability thereby impacting the transient or stable interactions with their adjacent neighbors in the organized and dynamic cellular interior. Using classical Brownian motion to elucidate the diffusion behavior of these biomolecules is hard considering their complex nature. The understanding of biomolecular diffusion inside cells still remains elusive due to the lack of a proper model that can be extrapolated to these cases. In this review, we have comprehensively addressed the progresses in this field, laying emphasis on the different aspects of anomalous diffusion in the different biochemical reactions in cell interior. These experiment-based models help to explain the diffusion behavior of biomolecules in the cytosolic and nuclear microenvironment. Moreover, since understanding of biochemical reactions within living cellular system is our main focus, we coupled the experimental observations with the concept of sub-diffusion from in vitro to in vivo condition. We believe that the pairing between the understanding of complex behavior and structure-function paradigm of biological molecules would take us forward by one step in order to solve the puzzle around diseases caused by cellular dysfunction.
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Affiliation(s)
- Sujit Basak
- Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA.
| | - Sombuddha Sengupta
- Protein Folding and Dynamics Lab, Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology (CSIR-IICB), 4 Raja S.C Mullick Road, Jadavpur, Kolkata, West Bengal, 700032, India
| | - Krishnananda Chattopadhyay
- Protein Folding and Dynamics Lab, Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology (CSIR-IICB), 4 Raja S.C Mullick Road, Jadavpur, Kolkata, West Bengal, 700032, India
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23
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Dear BJ, Chowdhury A, Hung JJ, Karouta CA, Ramachandran K, Nieto MP, Wilks LR, Sharma A, Shay TY, Cheung JK, Truskett TM, Johnston KP. Relating Collective Diffusion, Protein–Protein Interactions, and Viscosity of Highly Concentrated Monoclonal Antibodies through Dynamic Light Scattering. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b03432] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Barton J. Dear
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Amjad Chowdhury
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jessica J. Hung
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Carl A. Karouta
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Kishan Ramachandran
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Maria P. Nieto
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Logan R. Wilks
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Ayush Sharma
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Tony Y. Shay
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jason K. Cheung
- Biophysical and Biochemical Characterization, Sterile Formulation Sciences, Merck & Co., Inc., Kenilworth, New Jersey 07033, United States
| | - Thomas M. Truskett
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Keith P. Johnston
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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24
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Collins M, Mohajerani F, Ghosh S, Guha R, Lee TH, Butler PJ, Sen A, Velegol D. Nonuniform Crowding Enhances Transport. ACS NANO 2019; 13:8946-8956. [PMID: 31291087 DOI: 10.1021/acsnano.9b02811] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The cellular cytoplasm is crowded with macromolecules and other species that occupy up to 40% of the available volume. Previous studies have reported that for high crowder molecule concentrations, colloidal tracer particles have a dampened diffusion due to the higher solution viscosity. However, these studies employed uniform distributions of crowder molecules. We report a scenario, previously unexplored experimentally, of increased tracer transport driven by a nonuniform concentration of crowder macromolecules. In gradients of a polymeric crowder, tracer particles undergo transport several times higher than that of their bulk diffusion rate. The direction of the transport is toward regions of lower crowder concentration. Mechanistically, hard-sphere interactions and the resulting volume exclusion between the tracer and crowder increase the effective diffusion by inducing a convective motion of tracers, which we explain through modeling. Strikingly, soft deformable particles show even greater enhancement in transport in crowder gradients compared to similarly sized hard particles. Overall, this demonstration of enhanced transport in nonuniform distributions of crowders is anticipated to clarify aspects of multicomponent intracellular transport.
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25
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Structural Analysis and Dynamic Processes of the Transmembrane Segment Inside Different Micellar Environments-Implications for the TM4 Fragment of the Bilitranslocase Protein. Int J Mol Sci 2019; 20:ijms20174172. [PMID: 31454948 PMCID: PMC6747479 DOI: 10.3390/ijms20174172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/18/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022] Open
Abstract
The transmembrane (TM) proteins are gateways for molecular transport across the cell membrane that are often selected as potential targets for drug design. The bilitranslocase (BTL) protein facilitates the uptake of various anions, such as bilirubin, from the blood into the liver cells. As previously established, there are four hydrophobic transmembrane segments (TM1-TM4), which constitute the structure of the transmembrane channel of the BTL protein. In our previous studies, the 3D high-resolution structure of the TM2 and TM3 transmembrane fragments of the BTL in sodium dodecyl sulfate (SDS) micellar media were solved using Nuclear Magnetic Resonance (NMR) spectroscopy and molecular dynamics simulations (MD). The high-resolution 3D structure of the fourth transmembrane region (TM4) of the BTL was evaluated using NMR spectroscopy in two different micellar media, anionic SDS and zwitterionic DPC (dodecylphosphocholine). The presented experimental data revealed the existence of an α -helical conformation in the central part of the TM4 in both micellar media. In the case of SDS surfactant, the α -helical conformation is observed for the Pro258-Asn269 region. The use of the zwitterionic DPC micelle leads to the formation of an amphipathic α -helix, which is characterized by the extension of the central α -helix in the TM4 fragment to Phe257-Thr271. The complex character of the dynamic processes in the TM4 peptide within both surfactants was analyzed based on the relaxation data acquired on 15 N and 31 P isotopes. Contrary to previously published and present observations in the SDS micelle, the zwitterionic DPC environment leads to intensive low-frequency molecular dynamic processes in the TM4 fragment.
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26
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Barros W. Solvent self-diffusion dependence on the swelling degree of a hydrogel. Phys Rev E 2019; 99:052501. [PMID: 31212550 DOI: 10.1103/physreve.99.052501] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Indexed: 11/07/2022]
Abstract
This article describes high-field nuclear magnetic resonance experiments using pulsed gradient spin echo methods to investigate water mobility inside homogeneously swollen polyacrylamide hydrogel beads. The NMR data permitted determining the solvent self-diffusion coefficient dependence on either the swelling time or the polymer volume fraction. The sensitivity to the structure of the hydrogel network could be tuned to a certain extent via controlling the diffusion probing time. Relaxation measurements have helped substantiate a theoretical description for these self-diffusion dependencies based upon a fast-exchange two-site model. A tortuosity-porosity dependence is extracted from the model and then compared to other known tortuosity regimes. The diffusion dependence on the degree of swelling obtained here corroborates the existence of a gel swelling-front observed during inhomogeneous solvent imbibition experiments. Finally, we stress that the NMR experimental results reported here are of great value on performing theoretical modeling of gel swelling via solvent imbibition.
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Affiliation(s)
- Wilson Barros
- Departamento de Física, Universidade Federal de Pernambuco (UFPE), Cidade Universitária 50670-901 Recife, Pernambuco, Brazil
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27
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Douglas JF, Curtis R, S Sarangapani P, D Hudson S, L Jones R, A Pathak J. Hard Spheres with Purely Repulsive Interactions Have Positive Diffusion Interaction Parameter, k D. Biophys J 2019; 113:753-754. [PMID: 28793228 DOI: 10.1016/j.bpj.2017.03.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/10/2017] [Accepted: 03/20/2017] [Indexed: 11/30/2022] Open
Affiliation(s)
- Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland
| | - Robin Curtis
- School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, United Kingdom
| | | | - Steven D Hudson
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland
| | - Ronald L Jones
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland
| | - Jai A Pathak
- Vaccine Production Program (VPP), Vaccine Research Center (VRC), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Gaithersburg, Maryland.
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28
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Dodero A, Williams R, Gagliardi S, Vicini S, Alloisio M, Castellano M. A micro-rheological and rheological study of biopolymers solutions: Hyaluronic acid. Carbohydr Polym 2019; 203:349-355. [DOI: 10.1016/j.carbpol.2018.09.072] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/05/2018] [Accepted: 09/27/2018] [Indexed: 12/13/2022]
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Abstract
The concept of cell signaling in the context of nonenzyme-assisted protein modifications by reactive electrophilic and oxidative species, broadly known as redox signaling, is a uniquely complex topic that has been approached from numerous different and multidisciplinary angles. Our Review reflects on five aspects critical for understanding how nature harnesses these noncanonical post-translational modifications to coordinate distinct cellular activities: (1) specific players and their generation, (2) physicochemical properties, (3) mechanisms of action, (4) methods of interrogation, and (5) functional roles in health and disease. Emphasis is primarily placed on the latest progress in the field, but several aspects of classical work likely forgotten/lost are also recollected. For researchers with interests in getting into the field, our Review is anticipated to function as a primer. For the expert, we aim to stimulate thought and discussion about fundamentals of redox signaling mechanisms and nuances of specificity/selectivity and timing in this sophisticated yet fascinating arena at the crossroads of chemistry and biology.
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Affiliation(s)
- Saba Parvez
- Department of Pharmacology and Toxicology, College of
Pharmacy, University of Utah, Salt Lake City, Utah, 84112, USA
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Marcus J. C. Long
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Jesse R. Poganik
- Ecole Polytechnique Fédérale de Lausanne,
Institute of Chemical Sciences and Engineering, 1015, Lausanne, Switzerland
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Yimon Aye
- Ecole Polytechnique Fédérale de Lausanne,
Institute of Chemical Sciences and Engineering, 1015, Lausanne, Switzerland
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
- Department of Biochemistry, Weill Cornell Medicine, New
York, New York, 10065, USA
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30
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Kang S, Wang Y“W, Xu X, Navarro E, Tichauer KM, Liu JT. Microscopic investigation of" topically applied nanoparticles for molecular imaging of fresh tissue surfaces. JOURNAL OF BIOPHOTONICS 2018; 11:e201700246. [PMID: 29227576 PMCID: PMC5903997 DOI: 10.1002/jbio.201700246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/07/2017] [Indexed: 05/04/2023]
Abstract
Previous studies have shown that functionalized nanoparticles (NPs) topically applied on fresh tissues are able to rapidly target cell-surface protein biomarkers of cancer. Furthermore, studies have shown that a paired-agent approach, in which an untargeted NP is co-administered with a panel of targeted NPs, controls for the nonspecific behavior of the NPs, enabling quantitative imaging of biomarker expression. However, given the complexities in nonspecific accumulation, diffusion, and chemical binding of targeted NPs in tissues, studies are needed to better understand these processes at the microscopic scale. Here, fresh tissues were stained with a paired-agent approach, frozen, and sectioned to image the depth-dependent accumulation of targeted and untargeted NPs. The ratio of targeted-to-untargeted NP concentrations-a parameter used to distinguish between tumor and benign tissues-was found to diminish with increasing NP diffusion depths due to nonspecific accumulation and poor washout. It was then hypothesized and experimentally demonstrated that larger NPs would exhibit less diffusion below tissue surfaces, enabling higher targeted-to-untargeted NP ratios. In summary, these methods and investigations have enabled the design of NP agents with improved sensitivity and contrast for rapid molecular imaging of fresh tissues.
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Affiliation(s)
- Soyoung Kang
- Department of Mechanical Engineering, University of Washington, Seattle, WA
| | - Yu “Winston” Wang
- Department of Mechanical Engineering, University of Washington, Seattle, WA
| | - Xiaochun Xu
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL
| | - Eric Navarro
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL
| | - Kenneth M. Tichauer
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL
| | - Jonathan T.C. Liu
- Department of Mechanical Engineering, University of Washington, Seattle, WA
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31
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Bueno L, Amador C, Bakalis S. Modeling the deposition of fluorescent whitening agents on cotton fabrics. AIChE J 2017. [DOI: 10.1002/aic.16001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Laura Bueno
- School of Chemical Engineering; University of Birmingham; Birmingham B15 2TT U.K
| | - Carlos Amador
- Newcastle Innovation Centre, Procter & Gamble Ltd.; Newcastle Upon Tyne NE12 9BZ U.K
| | - Serafim Bakalis
- Dept. of Chemical and Environmental Engineering; University of Nottingham; Nottingham NG7 2RD U.K
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32
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Felderhof BU. Generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture. J Chem Phys 2017; 147:074902. [DOI: 10.1063/1.4993958] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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33
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Burgos-Mármol JJ, Álvarez-Machancoses Ó, Patti A. Modeling the Effect of Polymer Chain Stiffness on the Behavior of Polymer Nanocomposites. J Phys Chem B 2017; 121:6245-6256. [PMID: 28537739 DOI: 10.1021/acs.jpcb.7b02502] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Due to their central role in industrial formulations spanning from food packaging to smart coatings, polymer nanocomposites have been the object of remarkable attention over the last two decades. Incorporating nanoparticles (NPs) into a polymer matrix modifies the conformation and mobility of the polymer chains at the NP-polymer interface and can potentially provide materials with enhanced properties as compared to pristine polymers. To this end, it is crucial to predict and control the ability of NPs to diffuse and achieve a good dispersion in the polymer matrix. Understanding how to control the NPs' dispersion is a challenging task controlled by the delicate balance between enthalpic and entropic contributions, such as NP-polymer interaction, NP size and shape, and polymer chain conformation. By performing molecular dynamics (MD) simulations, we investigate the effect of polymer chains' stiffness on the mobility of spherical NPs that establish weak or strong interactions with the polymer. Our results show a sound dependence of the NPs' diffusivity on the long-range order of the polymer melt, which undergoes an isotropic-to-nematic phase transition upon increasing chain stiffness. This phase transition induces a dynamical anisotropy in the nematic phase, with the NPs preferentially diffusing along the nematic director rather than in the directions perpendicular to it. Not only does this tendency determine the NPs' mobility and degree of dispersion in the polymer matrix, but it also influences the resistance to flow of the polymer nanocomposite when a shear is applied. In particular, to assess the role of the chains' conformation on the macroscopic response of our model PNC, we employ reverse nonequilibrium MD to calculate the zero-shear viscosity in both the isotropic and nematic phases, and unveil a plasticizing effect at increasing chain stiffness when the shear is applied along the nematic axis.
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Affiliation(s)
- J Javier Burgos-Mármol
- School of Chemical Engineering and Analytical Science, The University of Manchester , Sackville Street, Manchester M13 9PL, U.K
| | - Óscar Álvarez-Machancoses
- School of Chemical Engineering and Analytical Science, The University of Manchester , Sackville Street, Manchester M13 9PL, U.K
| | - Alessandro Patti
- School of Chemical Engineering and Analytical Science, The University of Manchester , Sackville Street, Manchester M13 9PL, U.K
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34
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The Role of Shearing Energy and Interfacial Gibbs Free Energy in the Emulsification Mechanism of Waxy Crude Oil. ENERGIES 2017. [DOI: 10.3390/en10050721] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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35
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36
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Predoi D, Popa CL, Predoi MV. Ultrasound studies on magnetic fluids based on maghemite nanoparticles. POLYM ENG SCI 2017. [DOI: 10.1002/pen.24501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Daniela Predoi
- National Institute of Materials Physics; 405A Atomistilor Street Magurele Romania
| | - Cristina L. Popa
- National Institute of Materials Physics; 405A Atomistilor Street Magurele Romania
| | - Mihai V. Predoi
- Department of Mechanics; University Politechnica of Bucharest; Bucharest Romania
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37
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38
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Bardhan S, Kundu K, Kar B, Chakraborty G, Ghosh D, Sarkar D, Das S, Senapati S, Saha SK, Paul BK. Synergistic interactions of surfactant blends in aqueous medium are reciprocated in non-polar medium with improved efficacy as a nanoreactor. RSC Adv 2016. [DOI: 10.1039/c6ra06776j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Efficient soft chemical nanoreactors: a design strategy to improve the performance of a model C–C cross coupling (Heck) reaction under nanoscopic confinement of surfactant blends.
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Affiliation(s)
- Soumik Bardhan
- Department of Chemistry
- University of North Bengal
- Darjeeling-734 013
- India
| | - Kaushik Kundu
- Surface and Colloid Science Laboratory
- Geological Studies Unit
- Indian Statistical Institute
- Kolkata-700 108
- India
| | - Barnali Kar
- Department of Chemistry
- University of North Bengal
- Darjeeling-734 013
- India
| | - Gulmi Chakraborty
- Department of Chemistry
- University of North Bengal
- Darjeeling-734 013
- India
| | - Dibbendu Ghosh
- Department of Biotechnology
- Bhupat and Jyoti Mehta School of Biosciences
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Debayan Sarkar
- Department of Chemistry
- National Institute of Technology
- Rourkela
- India
| | - Sajal Das
- Department of Chemistry
- University of North Bengal
- Darjeeling-734 013
- India
| | - Sanjib Senapati
- Department of Biotechnology
- Bhupat and Jyoti Mehta School of Biosciences
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Swapan K. Saha
- Department of Chemistry
- University of North Bengal
- Darjeeling-734 013
- India
| | - Bidyut K. Paul
- Surface and Colloid Science Laboratory
- Geological Studies Unit
- Indian Statistical Institute
- Kolkata-700 108
- India
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39
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Riest J, Nägele G. Short-time dynamics in dispersions with competing short-range attraction and long-range repulsion. SOFT MATTER 2015; 11:9273-9280. [PMID: 26426932 DOI: 10.1039/c5sm02099a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Dynamic clustering of globular Brownian particles in dispersions exhibiting competing short-range attraction and long-range repulsion (SALR) such as low-salinity protein solutions has gained a lot of interest over the past few years. While the structure of the various cluster phases has been intensely explored, little is known about the dynamics of SALR systems. We present the first systematic theoretical study of short-time diffusion and rheological transport properties of two-Yukawa potential SALR systems in the single-particle dominated dispersed-fluid phase, using semi-analytic methods where the salient hydrodynamic interactions are accounted for. We show that the dynamics has unusual features compared to reference systems with pure repulsion or attraction. Results are discussed for the hydrodynamic function characterizing short-time diffusion that reveals an intermediate-range-order (cluster) peak, self-diffusion and sedimentation coefficients, and high-frequency viscosity. As important applications, we discuss the applicability of two generalized Stokes-Einstein relations, and assess the wavenumber range required for the determination of self-diffusion in a dynamic scattering experiment.
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Affiliation(s)
- Jonas Riest
- Forschungszentrum Jülich GmbH, ICS-3 - Soft Condensed Matter, 52425 Jülich, Germany. and Jülich-Aachen Research Alliance JARA - Soft Matter, 52425 Jülich, Germany
| | - Gerhard Nägele
- Forschungszentrum Jülich GmbH, ICS-3 - Soft Condensed Matter, 52425 Jülich, Germany. and Jülich-Aachen Research Alliance JARA - Soft Matter, 52425 Jülich, Germany
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40
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Prakash J, Pivin J, Swart H. Noble metal nanoparticles embedding into polymeric materials: From fundamentals to applications. Adv Colloid Interface Sci 2015; 226:187-202. [PMID: 26584861 DOI: 10.1016/j.cis.2015.10.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 12/14/2022]
Abstract
This review covers some key concepts related to embedding of the noble metal nanoparticles in polymer surfaces. The metal nanoparticles embedded into the polymer matrix can provide high-performance novel materials that find applications in modern nanotechnology. In particular, the origin of various processes that drive the embedding phenomenon, growth of the nanostructure at the surface, factors affecting the embedding including role of surface, interface energies and thermodynamic driving forces with emphasis on the fundamental and technological applications, under different conditions (annealing and ion beams) have been discussed. In addition to the conventional thermal process for embedding which includes the measure of fundamental polymer surface properties with relevant probing techniques, this review discusses the recent advances carried out in the understanding of embedding phenomenon starting from thin metal films to growth of the nanoparticles and embedded nanostructures using novel ion beam techniques.
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41
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Affiliation(s)
- Han Wang
- State
Key Laboratory of Multiphase Complex Systems, Institute of Process
Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongsheng Han
- State
Key Laboratory of Multiphase Complex Systems, Institute of Process
Engineering, Chinese Academy of Sciences, Beijing 100190, China
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42
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Mendoza CI, Santamaría-Holek I, Pérez-Madrid A. Effective temperatures and the breakdown of the Stokes-Einstein relation for particle suspensions. J Chem Phys 2015; 143:104506. [PMID: 26374049 DOI: 10.1063/1.4930550] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The short- and long-time breakdown of the classical Stokes-Einstein relation for colloidal suspensions at arbitrary volume fractions is explained here by examining the role that confinement and attractive interactions play in the intra- and inter-cage dynamics executed by the colloidal particles. We show that the measured short-time diffusion coefficient is larger than the one predicted by the classical Stokes-Einstein relation due to a non-equilibrated energy transfer between kinetic and configuration degrees of freedom. This transfer can be incorporated in an effective kinetic temperature that is higher than the temperature of the heat bath. We propose a Generalized Stokes-Einstein relation (GSER) in which the effective temperature replaces the temperature of the heat bath. This relation then allows to obtain the diffusion coefficient once the viscosity and the effective temperature are known. On the other hand, the temporary cluster formation induced by confinement and attractive interactions of hydrodynamic nature makes the long-time diffusion coefficient to be smaller than the corresponding one obtained from the classical Stokes-Einstein relation. Then, the use of the GSER allows to obtain an effective temperature that is smaller than the temperature of the heat bath. Additionally, we provide a simple expression based on a differential effective medium theory that allows to calculate the diffusion coefficient at short and long times. Comparison of our results with experiments and simulations for suspensions of hard and porous spheres shows an excellent agreement in all cases.
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Affiliation(s)
- Carlos I Mendoza
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo. Postal 70-360, 04510 México, D.F., Mexico
| | - I Santamaría-Holek
- UMDI-Facultad de Ciencias, Universidad Nacional Autónoma de México Campus Juriquilla, 76230 Querétaro, Mexico
| | - A Pérez-Madrid
- Departament de Física Fonamental, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona, Spain
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43
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Royer JR, Burton GL, Blair DL, Hudson SD. Rheology and dynamics of colloidal superballs. SOFT MATTER 2015; 11:5656-65. [PMID: 26078036 DOI: 10.1039/c5sm00729a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Recent advances in colloidal synthesis make it possible to generate a wide array of precisely controlled, non-spherical particles. This provides a unique opportunity to probe the role that particle shape plays in the dynamics of colloidal suspensions, particularly at higher volume fractions, where particle interactions are important. We examine the role of particle shape by characterizing both the bulk rheology and micro-scale diffusion in a suspension of pseudo-cubic silica superballs. Working with these well-characterized shaped colloids, we can disentangle shape effects in the hydrodynamics of isolated particles from shape-mediated particle interactions. We find that the hydrodynamic properties of isolated superballs are marginally different from comparably sized hard spheres. However, shape-mediated interactions modify the suspension microstructure, leading to significant differences in the self-diffusion of the superballs. While this excluded volume interaction can be captured with a rescaling of the superball volume fraction, we observe qualitative differences in the shear thickening behavior of moderately concentrated superball suspensions that defy simple rescaling onto hard sphere results. This study helps to define the unknowns associated with the effects of shape on the rheology and dynamics of colloidal solutions.
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Affiliation(s)
- John R Royer
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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44
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Chen L, Huang L, Zhu J. Stitching graphene oxide sheets into a membrane at a liquid/liquid interface. Chem Commun (Camb) 2014; 50:15944-7. [DOI: 10.1039/c4cc07558g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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46
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Chon B, Briggman K, Hwang J. Single molecule confocal fluorescence lifetime correlation spectroscopy for accurate nanoparticle size determination. Phys Chem Chem Phys 2014; 16:13418-25. [DOI: 10.1039/c4cp01197j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimental procedure in confocal single molecule fluorescence lifetime correlation spectroscopy to determine the excitation power and molecular or particulate concentration under which the application of an unmodified model autocorrelation function is justified.
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Affiliation(s)
- Bonghwan Chon
- Quantum Electronics and Photonics Division
- Physical Measurement Laboratory
- National Institute of Standards and Technology
- Boulder, USA
| | - Kimberly Briggman
- Quantum Electronics and Photonics Division
- Physical Measurement Laboratory
- National Institute of Standards and Technology
- Boulder, USA
| | - Jeeseong Hwang
- Quantum Electronics and Photonics Division
- Physical Measurement Laboratory
- National Institute of Standards and Technology
- Boulder, USA
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47
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Das T, Kutty SK, Kumar N, Manefield M. Pyocyanin facilitates extracellular DNA binding to Pseudomonas aeruginosa influencing cell surface properties and aggregation. PLoS One 2013; 8:e58299. [PMID: 23505483 PMCID: PMC3594310 DOI: 10.1371/journal.pone.0058299] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 02/01/2013] [Indexed: 11/26/2022] Open
Abstract
Pyocyanin is an electrochemically active metabolite produced by the human pathogen Pseudomonas aeruginosa. It is a recognized virulence factor and is involved in a variety of significant biological activities including gene expression, maintaining fitness of bacterial cells and biofilm formation. It is also recognized as an electron shuttle for bacterial respiration and as an antibacterial and antifungal agent. eDNA has also been demonstrated to be a major component in establishing P. aeruginosa biofilms. In this study we discovered that production of pyocyanin influences the binding of eDNA to P. aeruginosa PA14 cells, mediated through intercalation of pyocyanin with eDNA. P. aeruginosa cell surface properties including cell size (hydrodynamic diameter), hydrophobicity and attractive surface energies were influenced by eDNA in the presence of pyocyanin, affecting physico-chemical interactions and promoting aggregation. A ΔphzA-G PA14 mutant, deficient in pyocynain production, could not bind with eDNA resulting in a reduction in hydrodynamic diameter, a decrease in hydrophobicity, repulsive physico-chemical interactions and reduction in aggregation in comparison to the wildtype strain. Removal of eDNA by DNase I treatment on the PA14 wildtype strain resulted in significant reduction in aggregation, cell surface hydrophobicity and size and an increase in repulsive physico-chemical interactions, similar to the level of the ΔphzA-G mutant. The cell surface properties of the ΔphzA-G mutant were not affected by DNase I treatment. Based on these findings we propose that pyocyanin intercalation with eDNA promotes cell-to-cell interactions in P. aeruginosa cells by influencing their cell surface properties and physico-chemical interactions.
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Affiliation(s)
- Theerthankar Das
- Centre for Marine BioInnovation (CMB), School of Biotechnology and Biomolecular Sciences (BABS), University of New South Wales (UNSW), Sydney, Australia.
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48
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Heinen M, Banchio AJ, Nägele G. Short-time rheology and diffusion in suspensions of Yukawa-type colloidal particles. J Chem Phys 2012; 135:154504. [PMID: 22029321 DOI: 10.1063/1.3646962] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A comprehensive study is presented on the short-time dynamics in suspensions of charged colloidal spheres. The explored parameter space covers the major part of the fluid-state regime, with colloid concentrations extending up to the freezing transition. The particles are assumed to interact directly by a hard-core plus screened Coulomb potential, and indirectly by solvent-mediated hydrodynamic interactions. By comparison with accurate accelerated Stokesian Dynamics (ASD) simulations of the hydrodynamic function H(q), and the high-frequency viscosity η(∞), we investigate the accuracy of two fast and easy-to-implement analytical schemes. The first scheme, referred to as the pairwise additive (PA) scheme, uses exact two-body hydrodynamic mobility tensors. It is in good agreement with the ASD simulations of H(q) and η(∞), for smaller volume fractions up to about 10% and 20%, respectively. The second scheme is a hybrid method combining the virtues of the δγ scheme by Beenakker and Mazur with those of the PA scheme. It leads to predictions in good agreement with the simulation data, for all considered concentrations, combining thus precision with computational efficiency. The hybrid method is used to test the accuracy of a generalized Stokes-Einstein (GSE) relation proposed by Kholodenko and Douglas, showing its severe violation in low salinity systems. For hard spheres, however, this GSE relation applies decently well.
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Affiliation(s)
- Marco Heinen
- Institute of Complex Systems (ICS-3), Forschungszentrum Jülich, D-52425 Jülich, Germany.
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49
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Wang Y, Zocchi G. Viscoelastic transition and yield strain of the folded protein. PLoS One 2011; 6:e28097. [PMID: 22174767 PMCID: PMC3234265 DOI: 10.1371/journal.pone.0028097] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 11/01/2011] [Indexed: 11/19/2022] Open
Abstract
For proteins, the mechanical properties of the folded state are directly related to function, which generally entails conformational motion. Through sub-Angstrom resolution measurements of the AC mechanical susceptibility of a globular protein we describe a new fundamental materials property of the folded state. For increasing amplitude of the forcing, there is a reversible transition from elastic to viscoelastic response. At fixed frequency, the amplitude of the deformation is piecewise linear in the force, with different slopes in the elastic and viscoelastic regimes. Effectively, the protein softens beyond a yield point defined by this transition. We propose that ligand induced conformational changes generally operate in this viscoelastic regime, and that this is a universal property of the folded state.
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Affiliation(s)
- Yong Wang
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California, United States of America
| | - Giovanni Zocchi
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California, United States of America
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50
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Hsu THT, Naidu JJ, Yang BJ, Jang MY, Lin IJB. Self-Assembly of Silver(I) and Gold(I) N-Heterocyclic Carbene Complexes in Solid State, Mesophase, and Solution. Inorg Chem 2011; 51:98-108. [DOI: 10.1021/ic2011343] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tina H. T. Hsu
- Department of Chemistry and
Nanotechnology Research Center, National Dong Hwa University, Hualien, 974, Taiwan
| | - Jaishri J. Naidu
- Department of Chemistry and
Nanotechnology Research Center, National Dong Hwa University, Hualien, 974, Taiwan
| | - Bi-Jiuan Yang
- Department of Chemistry, Fu-Jen Catholic University, Hsinchuang, Taipei, 242,
Taiwan
| | - Meng-Ying Jang
- Department of Chemistry and
Nanotechnology Research Center, National Dong Hwa University, Hualien, 974, Taiwan
| | - Ivan J. B. Lin
- Department of Chemistry and
Nanotechnology Research Center, National Dong Hwa University, Hualien, 974, Taiwan
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