1
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Pavón C, Ongaro A, Filipucci I, Ramakrishna SN, Mattarei A, Isa L, Klok HA, Lorandi F, Benetti EM. The Structural Dispersity of Oligoethylene Glycol-Containing Polymer Brushes Determines Their Interfacial Properties. J Am Chem Soc 2024. [PMID: 38859572 DOI: 10.1021/jacs.4c05565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Ought to their bioinert properties and facile synthesis, poly[(oligoethylene glycol)methacrylate]s (POEGMAs) have been raised as attractive alternatives to poly(ethylene glycols) (PEGs) in an array of (bio)material applications, especially when they are applied as polymer brush coatings. However, commercially available OEG-methacrylate (macro)monomers feature a broad distribution of OEG lengths, thus generating structurally polydisperse POEGMAs when polymerized through reversible deactivation radical polymerization. Here, we demonstrate that the interfacial physicochemical properties of POEGMA brushes are significantly affected by their structural dispersity, i.e., the degree of heterogeneity in the length of side OEG segments. POEGMA brushes synthesized from discrete (macro)monomers obtained through chromatographic purification of commercial mixtures show increased hydration and reduced adhesion when compared to their structurally polydisperse analogues. The observed alteration of interfacial properties is directly linked to the presence of monodisperse OEG side chains, which hamper intramolecular and intermolecular hydrophobic interactions while simultaneously promoting the association of water molecules. These phenomena provide structurally homogeneous POEGMA brushes with a more lubricious and protein repellent character with respect to their heterogeneous counterparts. More generally, in contrast to what has been assumed until now, the properties of POEGMA brushes cannot be anticipated while ruling out the effect of dispersity by (macro)monomer feeds. Simultaneously, side chain dispersity of POEGMAs emerges as a critical parameter for determining the interfacial characteristics of brushes.
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Affiliation(s)
- Carlos Pavón
- Laboratory for Macromolecular and Organic Chemistry, Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Alberto Ongaro
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
| | - Irene Filipucci
- Laboratory for Macromolecular and Organic Chemistry, Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymeres, École Polytechnique Fédérale de Lausanne (EPFL), Rte Cantonale, CH-1015 Lausanne, Switzerland
| | - Shivaprakash N Ramakrishna
- Laboratory for Soft Materials and Interfaces, ETH Zürich, Vladmir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Andrea Mattarei
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, ETH Zürich, Vladmir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Harm-Anton Klok
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymeres, École Polytechnique Fédérale de Lausanne (EPFL), Rte Cantonale, CH-1015 Lausanne, Switzerland
| | - Francesca Lorandi
- Laboratory for Macromolecular and Organic Chemistry, Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Edmondo M Benetti
- Laboratory for Macromolecular and Organic Chemistry, Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
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2
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Wei B, Li H, Chu H, Dong H, Zhang Y, Sun CL, Li Y. Self-Assembly of Amphiphilic PDI and NDI Derivatives with Opposite Thermoresponsive Fluorescent Behaviors in Aqueous Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:6493-6505. [PMID: 38484325 DOI: 10.1021/acs.langmuir.4c00106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
This work presents a study of the thermally induced aggregation of perylene diimide (PDI) and naphthalene diimide (NDI) derivatives modified with oligo ethylene glycol (OEG) chains in aqueous solution. Water-soluble and flexible OEG side chains were introduced into the π-core of glutamate-modified NDI and PDI structures, and the aggregation process was modulated by heating or cooling in water. Interestingly, a rare opposite temperature response of fluorescent behavior from the two amphiphilic chromophores was revealed, in which the PDI exhibited fluorescent enhancement, while fluorescent quenching upon temperature increase was observed from the NDI assembly. The mechanism of thermally induced aggregation is clearly explained by studies with various spectroscopic techniques including UV-visible, fluorescence, 1H NMR, 2D NMR spectroscopy, and SEM observation as well as control experiments operated in DMSO solution. It is found that although similar J-aggregates were formed by both amphiphilic chromophores in aqueous solution, the temperature response of the aggregates to temperature was opposite. The degree of PDI aggregation decreased, while that of NDI increased upon temperature rising. This research paves a valuable way for understanding the complicated supramolecular behaviors of amphiphilic chromophores.
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Affiliation(s)
- Bizhuo Wei
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
| | - Huajing Li
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
| | - Huan Chu
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
| | - Huanhuan Dong
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
| | - Yijun Zhang
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
| | - Cai-Li Sun
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
| | - Yuangang Li
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, No. 58 Yanta Road, Xi'an 710054, China
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3
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Sánchez-Morán H, Kaar JL, Schwartz DK. Supra-biological performance of immobilized enzymes enabled by chaperone-like specific non-covalent interactions. Nat Commun 2024; 15:2299. [PMID: 38485940 PMCID: PMC10940687 DOI: 10.1038/s41467-024-46719-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 03/01/2024] [Indexed: 03/18/2024] Open
Abstract
Designing complex synthetic materials for enzyme immobilization could unlock the utility of biocatalysis in extreme environments. Inspired by biology, we investigate the use of random copolymer brushes as dynamic immobilization supports that enable supra-biological catalytic performance of immobilized enzymes. This is demonstrated by immobilizing Bacillus subtilis Lipase A on brushes doped with aromatic moieties, which can interact with the lipase through multiple non-covalent interactions. Incorporation of aromatic groups leads to a 50 °C increase in the optimal temperature of lipase, as well as a 50-fold enhancement in enzyme activity. Single-molecule FRET studies reveal that these supports act as biomimetic chaperones by promoting enzyme refolding and stabilizing the enzyme's folded and catalytically active state. This effect is diminished when aromatic residues are mutated out, suggesting the importance of π-stacking and π-cation interactions for stabilization. Our results underscore how unexplored enzyme-support interactions may enable uncharted opportunities for using enzymes in industrial biotransformations.
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Affiliation(s)
- Héctor Sánchez-Morán
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Campus Box 596, Boulder, CO, 80309, USA
| | - Joel L Kaar
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Campus Box 596, Boulder, CO, 80309, USA.
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Campus Box 596, Boulder, CO, 80309, USA.
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4
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Bisirri EA, Wright TA, Schwartz DK, Kaar JL. Tuning Polymer Composition Leads to Activity-Stability Tradeoff in Enzyme-Polymer Conjugates. Biomacromolecules 2023; 24:4033-4041. [PMID: 37610792 DOI: 10.1021/acs.biomac.3c00396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Protein-polymer conjugation provides an opportune means to adjust the local environment of proteins and enhance protein stability, performance, and solubility. Although much attention has been focused on tuning protein-polymer interactions, the properties of polymer-modified proteins may also be altered by polymer-polymer interactions. Herein, we sought to better understand the influence of polymer-polymer interactions on Candida rugosa lipase, which was modified with random co-polymers composed of sulfobetaine methacrylate (SBMA) and poly(ethylene glycol) methacrylate (PEGMA). Our findings suggest that there is an apparent activity-stability tradeoff as a function of polymer composition. Specifically, as the ratio of SBMA to PEGMA increased, lipase stability was enhanced, whereas activity decreased. By tuning the monomer ratio, we showed that lipase productivity could be optimized. These findings are discussed in the context of complex enzyme-polymer and polymer-polymer interactions and ultimately may enable more informed conjugate designs and improved enzyme productivity in industrial biotransformations under harsh or extreme conditions.
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Affiliation(s)
- Evan A Bisirri
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Thaiesha A Wright
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Joel L Kaar
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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5
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Thompson CJ, Kienle DF, Schwartz DK. Enhanced Facilitated Diffusion of Membrane-Associating Proteins under Symmetric Confinement. J Phys Chem Lett 2022; 13:2901-2907. [PMID: 35333540 DOI: 10.1021/acs.jpclett.2c00227] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The facilitated surface diffusion of transiently adsorbing molecules in a planar confined microenvironment (i.e., slit-like confinement) is highly relevant to biological phenomena, such as extracellular signaling, as well as numerous biotechnology systems. Here, we studied the surface diffusion of individual proteins confined between two symmetric lipid bilayer membranes, under a continuum of confinement heights, using single-molecule tracking and convex lens-induced confinement as well as hybrid, kinetic Monte Carlo simulations of a generalized continuous time random walk process. Surface diffusion was observed to vary non-monotonically with confinement height, exhibiting a maximum at a height of ∼750 nm, where diffusion was nearly 40% greater than that for a semi-infinite system. This demonstrated that planar confinement can, in fact, increase surface diffusion, qualitatively validating previous theoretical predictions. Simulations reproduced the experimental results and suggested that confinement enhancement of surface diffusion for symmetric systems is limited to cases where the adsorbate exhibits weak surface sticking.
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Affiliation(s)
- Connor J Thompson
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Daniel F Kienle
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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6
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Xu G, Zhang J, Jia R, Li W, Zhang A. Topological Effects of Dendronized Polymers on Their Thermoresponsiveness and Microconfinement. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02066] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Gang Xu
- International Joint Laboratory of Biomimetic & Smart Polymers, School of Materials Science and Engineering, Shanghai University, Shangda Road 99, Shanghai 20444, China
| | - Jiaxing Zhang
- International Joint Laboratory of Biomimetic & Smart Polymers, School of Materials Science and Engineering, Shanghai University, Shangda Road 99, Shanghai 20444, China
| | - Ruitong Jia
- International Joint Laboratory of Biomimetic & Smart Polymers, School of Materials Science and Engineering, Shanghai University, Shangda Road 99, Shanghai 20444, China
| | - Wen Li
- International Joint Laboratory of Biomimetic & Smart Polymers, School of Materials Science and Engineering, Shanghai University, Shangda Road 99, Shanghai 20444, China
| | - Afang Zhang
- International Joint Laboratory of Biomimetic & Smart Polymers, School of Materials Science and Engineering, Shanghai University, Shangda Road 99, Shanghai 20444, China
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8
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Romio M, Grob B, Trachsel L, Mattarei A, Morgese G, Ramakrishna SN, Niccolai F, Guazzelli E, Paradisi C, Martinelli E, Spencer ND, Benetti EM. Dispersity within Brushes Plays a Major Role in Determining Their Interfacial Properties: The Case of Oligoxazoline-Based Graft Polymers. J Am Chem Soc 2021; 143:19067-19077. [PMID: 34738797 PMCID: PMC8769490 DOI: 10.1021/jacs.1c08383] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Indexed: 12/14/2022]
Abstract
Many synthetic polymers used to form polymer-brush films feature a main backbone with functional, oligomeric side chains. While the structure of such graft polymers mimics biomacromolecules to an extent, it lacks the monodispersity and structural purity present in nature. Here we demonstrate that side-chain heterogeneity within graft polymers significantly influences hydration and the occurrence of hydrophobic interactions in the subsequently formed brushes and consequently impacts fundamental interfacial properties. This is demonstrated for the case of poly(methacrylate)s (PMAs) presenting oligomeric side chains of different length (n) and dispersity. A precise tuning of brush structure was achieved by first synthesizing oligo(2-ethyl-2-oxazoline) methacrylates (OEOXMAs) by cationic ring-opening polymerization (CROP), subsequently purifying them into discrete macromonomers with distinct values of n by column chromatography, and finally obtaining poly[oligo(2-ethyl-2-oxazoline) methacrylate]s (POEOXMAs) by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Assembly of POEOXMA on Au surfaces yielded graft polymer brushes with different side-chain dispersities and lengths, whose properties were thoroughly investigated by a combination of variable angle spectroscopic ellipsometry (VASE), quartz crystal microbalance with dissipation (QCMD), and atomic force microscopy (AFM) methods. Side-chain dispersity, or dispersity within brushes, leads to assemblies that are more hydrated, less adhesive, and more lubricious and biopassive compared to analogous films obtained from graft polymers characterized by a homogeneous structure.
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Affiliation(s)
- Matteo Romio
- Biointerfaces
Lab, Swiss Federal Laboratories for Materials
Science and Technology (Empa), Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
- Laboratory
for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Benjamin Grob
- Laboratory
for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Lucca Trachsel
- George
& Josephine Butler Polymer Research Laboratory, Department of
Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Andrea Mattarei
- Department
of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy
| | - Giulia Morgese
- Institute
of Materials and Process Engineering (IMPE), School of Engineering
(SoE), Zürich University of Applied
Sciences (ZHAW), Technikumstrasse 9, 8401 Winterthur, Switzerland
| | - Shivaprakash N. Ramakrishna
- Soft Materials
and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg
5, 8093 Zürich, Switzerland
| | - Francesca Niccolai
- Department
of Chemistry and Industrial Chemistry, University
of Pisa, Via Moruzzi 13, 56124 Pisa, Italy
| | - Elisa Guazzelli
- Department
of Chemistry and Industrial Chemistry, University
of Pisa, Via Moruzzi 13, 56124 Pisa, Italy
| | - Cristina Paradisi
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35122 Padova, Italy
| | - Elisa Martinelli
- Department
of Chemistry and Industrial Chemistry, University
of Pisa, Via Moruzzi 13, 56124 Pisa, Italy
| | - Nicholas D. Spencer
- Laboratory
for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Edmondo M. Benetti
- Biointerfaces
Lab, Swiss Federal Laboratories for Materials
Science and Technology (Empa), Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
- Laboratory
for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35122 Padova, Italy
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9
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Sosa AFC, Bednar RM, Mehl RA, Schwartz DK, Kaar JL. Faster Surface Ligation Reactions Improve Immobilized Enzyme Structure and Activity. J Am Chem Soc 2021; 143:7154-7163. [PMID: 33914511 PMCID: PMC8574164 DOI: 10.1021/jacs.1c02375] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
During integration into materials, the inactivation of enzymes as a result of their interaction with nanometer size denaturing "hotspots" on surfaces represents a critical challenge. This challenge, which has received far less attention than improving the long-term stability of enzymes, may be overcome by limiting the exploration of surfaces by enzymes. One way this may be accomplished is through increasing the rate constant of the surface ligation reaction and thus the probability of immobilization with reactive surface sites (i.e., ligation efficiency). Here, the connection between ligation reaction efficiency and the retention of enzyme structure and activity was investigated by leveraging the extremely fast reaction of strained trans-cyclooctene (sTCOs) and tetrazines (Tet). Remarkably, upon immobilization via Tet-sTCO chemistry, carbonic anhydrase (CA) retained 77% of its solution-phase activity, while immobilization via less efficient reaction chemistries, such as thiol-maleimide and azide-dibenzocyclooctyne, led to activity retention of only 46% and 27%, respectively. Dynamic single-molecule fluorescence tracking methods further revealed that longer surface search distances prior to immobilization (>0.5 μm) dramatically increased the probability of CA unfolding. Notably, the CA distance to immobilization was significantly reduced through the use of Tet-sTCO chemistry, which correlated with the increased retention of structure and activity of immobilized CA compared to the use of slower ligation chemistries. These findings provide an unprecedented insight into the role of ligation reaction efficiency in mediating the exploration of denaturing hotspots on surfaces by enzymes, which, in turn, may have major ramifications in the creation of functional biohybrid materials.
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Affiliation(s)
- Andres F. Chaparro Sosa
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309
| | - Riley M. Bednar
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural & Life Sciences Building, Corvallis, OR 97331-7305
| | - Ryan A. Mehl
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural & Life Sciences Building, Corvallis, OR 97331-7305
| | - Daniel K. Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309
| | - Joel L. Kaar
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309
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10
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Kienle DF, Schwartz DK. Single molecule characterization of anomalous transport in a thin, anisotropic film. Anal Chim Acta 2021; 1154:338331. [PMID: 33736806 DOI: 10.1016/j.aca.2021.338331] [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] [Received: 12/24/2020] [Revised: 02/01/2021] [Accepted: 02/14/2021] [Indexed: 01/07/2023]
Abstract
The diffusion of small, charged molecules incorporated in an anisotropic polyelectrolyte multilayer (PEM) was tracked in three dimensions by combining single-molecule fluorescence localization (to characterize lateral diffusion) with Förster resonance energy transfer (FRET) between diffusing molecules and the supporting surface (to measure diffusion in the surface-normal direction). Analysis of the surface-normal diffusion required model-based statistical analysis to account for the inherently noisy FRET signal. Combining these distinct single-molecule methods, which are inherently sensitive to different length-scales, permitted simultaneous characterization of severely anisotropic diffusion, which was more than three orders of magnitude slower in the surface-normal direction. We hypothesize that the anomalously slow surface-normal diffusion was related to the periodic distribution of charge in the PEM, which created electrostatic barriers. The motion was strongly subdiffusive, with anomalous temporal scaling exponents in lateral and normal directions, suggesting a connection to the transient, random fractal conformation of polymer chains in the film's matrix.
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Affiliation(s)
- Daniel F Kienle
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80309, USA.
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11
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Thompson CJ, Vu VH, Leckband DE, Schwartz DK. Cadherin cis and trans interactions are mutually cooperative. Proc Natl Acad Sci U S A 2021; 118:e2019845118. [PMID: 33658369 PMCID: PMC7958404 DOI: 10.1073/pnas.2019845118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cadherin transmembrane proteins are responsible for intercellular adhesion in all biological tissues and modulate tissue morphogenesis, cell motility, force transduction, and macromolecular transport. The protein-mediated adhesions consist of adhesive trans interactions and lateral cis interactions. Although theory suggests cooperativity between cis and trans bonds, direct experimental evidence of such cooperativity has not been demonstrated. Here, the use of superresolution microscopy, in conjunction with intermolecular single-molecule Förster resonance energy transfer, demonstrated the mutual cooperativity of cis and trans interactions. Results further demonstrate the consequent assembly of large intermembrane junctions, using a biomimetic lipid bilayer cell adhesion model. Notably, the presence of cis interactions resulted in a nearly 30-fold increase in trans-binding lifetimes between epithelial-cadherin extracellular domains. In turn, the presence of trans interactions increased the lifetime of cis bonds. Importantly, comparison of trans-binding lifetimes of small and large cadherin clusters suggests that this cooperativity is primarily due to allostery. The direct quantitative demonstration of strong mutual cooperativity between cis and trans interactions at intermembrane adhesions provides insights into the long-standing controversy of how weak cis and trans interactions act in concert to create strong macroscopic cell adhesions.
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Affiliation(s)
- Connor J Thompson
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309
| | - Vinh H Vu
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801
| | - Deborah E Leckband
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309;
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12
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Wojtecki R, Ma J, Cordova I, Arellano N, Lionti K, Magbitang T, Pattison TG, Zhao X, Delenia E, Lanzillo N, Hess AE, Nathel NF, Bui H, Rettner C, Wallraff G, Naulleau P. Additive Lithography-Organic Monolayer Patterning Coupled with an Area-Selective Deposition. ACS APPLIED MATERIALS & INTERFACES 2021; 13:9081-9090. [PMID: 33471496 DOI: 10.1021/acsami.0c16817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The combination of area-selective deposition (ASD) with a patternable organic monolayer provides a versatile additive lithography platform, enabling the generation of a variety of nanoscale feature geometries. Stearate hydroxamic acid self-assembled monolayers (SAMs) were patterned with extreme ultraviolet (λ = 13.5 nm) or electron beam irradiation and developed with ASD to achieve line space patterns as small as 50 nm. Density functional theory was employed to aid in the synthesis of hydroxamic acid derivatives with optimized packing density to enhance the imaging contrast and improve dose sensitivity. Near-edge X-ray absorption fine structure spectroscopy and infrared spectroscopy reveal that the imaging mechanism is based on improved deposition inhibition provided by the cross-linking of the SAM to produce a more effective barrier during a subsequent deposition step. With patterned substrates composed of coplanar copper lines and silicon spacers, hydroxamic acids selectively formed monolayers on the metal portions and could undergo a pattern-wise exposure followed by ASD in the first combination of a patternable monolayer with ASD. This material system presents an additional capability compared to traditional ASD approaches that generally reflect a starting patterned surface. Furthermore, this bottoms-up additive approach to lithography may be a viable alternative to subtractive nanoscale feature generation.
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Affiliation(s)
- Rudy Wojtecki
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Jonathan Ma
- Center for X-ray Optics, Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, United States
| | - Isvar Cordova
- Center for X-ray Optics, Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, United States
| | - Noel Arellano
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Krystelle Lionti
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Teddie Magbitang
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Thomas G Pattison
- Polymer Science Group, Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Xiao Zhao
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, United States
| | - Eugene Delenia
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Nicholas Lanzillo
- International Business Machines-Semiconductor Technology Research, 257 Fuller Road, Albany, New York 12203, United States
| | - Alexander E Hess
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Noah Fine Nathel
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Holt Bui
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Charles Rettner
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Gregory Wallraff
- International Business Machines-Almaden Research Center, 650 Harry Road, San Jose, California 95110, United States
| | - Patrick Naulleau
- Center for X-ray Optics, Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, United States
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13
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Hedayati M, Krapf D, Kipper MJ. Dynamics of long-term protein aggregation on low-fouling surfaces. J Colloid Interface Sci 2021; 589:356-366. [PMID: 33482534 DOI: 10.1016/j.jcis.2021.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/13/2020] [Accepted: 01/01/2021] [Indexed: 01/12/2023]
Abstract
Understanding the mechanisms of protein interactions with solid surfaces is critical to predict how proteins affect the performance of materials in biological environments. Low-fouling and ultra-low fouling surfaces are often evaluated in short-term protein adsorption experiments, where 'short-term' is defined as the time required to reach an initial apparent or pseudo-equilibrium, which is usually less than 600 s. However, it has long been recognized that these short-term observations fail to predict protein adsorption behavior in the long-term, characterized by irreversible accumulation of protein on the surface. This important long-term behavior is frequently ignored or attributed to slow changes in surface chemistry over time-such as oxidation-often with little or no experimental evidence. Here, we report experiments measuring protein adsorption on "low-fouling" and "ultralow-fouling" surfaces using single-molecule localization microscopy to directly probe protein adsorption and desorption. The experiments detect protein adsorption for thousands of seconds, enabling direct observation of both short-term (reversible adsorption) and long-term (irreversible adsorption leading to accumulation) protein-surface interactions. By bridging the gap between these two time scales in a single experiment, this work enables us to develop a single mathematical model that predicts behavior in both temporal regimes. The experimental data in combination with the resulting model provide several important insights: (1) short-term measurements of protein adsorption using ensemble-averaging methods may not be sufficient for designing antifouling materials; (2) all investigated surfaces eventually foul when in long-term contact with protein solutions; (3) fouling can occur through surface-induced oligomerization of proteins which may be a distinct step from irreversible adsorption; and (4) surfaces can be designed to reduce oligomerization or the adsorption of oligomers, to prevent or delay fouling.
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Affiliation(s)
- Mohammadhasan Hedayati
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Diego Krapf
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA; School of Advanced Materials Discovery, Colorado State University, Fort Collins, CO 80523, USA; Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80523, USA.
| | - Matt J Kipper
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA; School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA; School of Advanced Materials Discovery, Colorado State University, Fort Collins, CO 80523, USA.
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14
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Gehlen MH, Foltran LS, Kienle DF, Schwartz DK. Single-Molecule Observations Provide Mechanistic Insights into Bimolecular Knoevenagel Amino Catalysis. J Phys Chem Lett 2020; 11:9714-9724. [PMID: 33136415 DOI: 10.1021/acs.jpclett.0c03030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
While single-molecule (SM) methods have provided new insights to various catalytic processes, bimolecular reactions have been particularly challenging to study. Here, the fluorogenic Knoevenagel condensation of an aromatic aldehyde with methyl cyanoacetate promoted by surface-immobilized piperazine is quantitatively characterized using super-resolution fluorescence imaging and stochastic analysis using hidden Markov modeling (HMM). Notably, the SM results suggest that the reaction follows the iminium intermediate pathway before the formation of a fluorescent product with intramolecular charge-transfer character. Moreover, the overall process is limited by the turnover rate of the catalyst, which is involved in multiple steps along the reaction coordinate.
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Affiliation(s)
- Marcelo H Gehlen
- Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, 13566-590 São Carlos, SP, Brazil
| | - Larissa S Foltran
- Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, 13566-590 São Carlos, SP, Brazil
| | - Daniel F Kienle
- Department of Chemistry and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemistry and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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15
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Thompson CJ, Su Z, Vu VH, Wu Y, Leckband DE, Schwartz DK. Cadherin clusters stabilized by a combination of specific and nonspecific cis-interactions. eLife 2020; 9:e59035. [PMID: 32876051 PMCID: PMC7505656 DOI: 10.7554/elife.59035] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/01/2020] [Indexed: 12/13/2022] Open
Abstract
We demonstrate a combined experimental and computational approach for the quantitative characterization of lateral interactions between membrane-associated proteins. In particular, weak, lateral (cis) interactions between E-cadherin extracellular domains tethered to supported lipid bilayers, were studied using a combination of dynamic single-molecule Förster Resonance Energy Transfer (FRET) and kinetic Monte Carlo (kMC) simulations. Cadherins are intercellular adhesion proteins that assemble into clusters at cell-cell contacts through cis- and trans- (adhesive) interactions. A detailed and quantitative understanding of cis-clustering has been hindered by a lack of experimental approaches capable of detecting and quantifying lateral interactions between proteins on membranes. Here single-molecule intermolecular FRET measurements of wild-type E-cadherin and cis-interaction mutants combined with simulations demonstrate that both nonspecific and specific cis-interactions contribute to lateral clustering on lipid bilayers. Moreover, the intermolecular binding and dissociation rate constants are quantitatively and independently determined, demonstrating an approach that is generalizable for other interacting proteins.
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Affiliation(s)
- Connor J Thompson
- Department of Chemical and Biological Engineering, University of Colorado BoulderBoulderUnited States
| | - Zhaoqian Su
- Department of Systems and Computational Biology, Albert Einstein College of MedicineBronxUnited States
| | - Vinh H Vu
- Department of Biochemistry and University of Illinois, Urbana-ChampaignUrbanaUnited States
| | - Yinghao Wu
- Department of Systems and Computational Biology, Albert Einstein College of MedicineBronxUnited States
| | - Deborah E Leckband
- Department of Biochemistry and University of Illinois, Urbana-ChampaignUrbanaUnited States
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana-ChampaignUrbanaUnited States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado BoulderBoulderUnited States
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16
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17
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Kienle DF, Chaparro Sosa AF, Kaar JL, Schwartz DK. Polyelectrolyte Multilayers Enhance the Dry Storage and pH Stability of Physically Entrapped Enzymes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:22640-22649. [PMID: 32352745 DOI: 10.1021/acsami.0c04964] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Polyelectrolyte multilayers (PEMs) are attractive materials for immobilizing enzymes due to their unique ionic environment, which can prevent unfolding. Here, we demonstrated that the stability to dry storage and elevated pH were significantly enhanced when negatively charged nitroreductase (NfsB) was embedded in a PEM by depositing alternating layers of the enzyme and polycation (PC) onto porous silica particles. The PC strength (i.e., pKa) and the surface charge of the film were varied to probe the effects that internal and surface chemistry had on the pH stability of the entrapped NfsB. All films showed enhanced activity retention at elevated pH (>6), and inactivation at reduced pH (<6) similar to NfsB in solution, indicating that the primary stabilizing effect of immobilization was achieved through ionic interactions between NfsB and the PC and not through changes to the surface charge of the NfsB. Additionally, films that were stored dry at 4 °C for 1 month retained full activity, while those stored at room temperature lost 30% activity. Remarkably, at 50 °C, above the NfsB melting temperature, 40% activity was retained after 1 month of dry storage. Our results suggest that internal film properties are significantly more important than surface charge, which had minor effects on activity. Specifically, immobilization with the weak PC, poly(l-lysine), increased the optimal pH and the activity of immobilized NfsB (which we attribute to greater permeability), relative to immobilization with the strong PC, poly(diallyldimethylammonium chloride). However, NfsB was leached from the PLL film to a greater extent. Overall, these observations demonstrate that internal ionic cross-linking is key to the stabilizing effects of PEMs and that the pH response can be tuned by controlling the number of cross-links (e.g., by changing the strength of the PC). However, this may be at the cost of reduced loading, illustrating the necessity of simultaneously optimizing enzyme loading, internal ionic cross-linking, and substrate transport.
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Affiliation(s)
- Daniel F Kienle
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Andres F Chaparro Sosa
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Joel L Kaar
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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18
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Morrin GT, Kienle DF, Weltz JS, Traeger JC, Schwartz DK. Polyelectrolyte Surface Diffusion in a Nanoslit Geometry. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02365] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gregory T. Morrin
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Daniel F. Kienle
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - James S. Weltz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Jeremiah C. Traeger
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Daniel K. Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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19
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Bolivar JM, Nidetzky B. On the relationship between structure and catalytic effectiveness in solid surface-immobilized enzymes: Advances in methodology and the quest for a single-molecule perspective. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1868:140333. [PMID: 31778816 DOI: 10.1016/j.bbapap.2019.140333] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 11/05/2019] [Accepted: 11/22/2019] [Indexed: 12/31/2022]
Abstract
The integration of enzymes with solid materials is important in many biotechnological applications, including the use of immobilized enzymes for biocatalytic synthesis. The development of functional enzyme-material composites is restrained by the lack of molecular-level insight into the behavior of enzymes in confined, surface-near environments. Here, we review recent advances in surface-sensitive spectroscopic techniques that push boundaries for the determination of enzyme structure and orientation at the solid-liquid interface. We discuss recent evidence from single-molecule studies showing that analyses sensitive to the temporal and spatial heterogeneities in immobilized enzymes can succeed in disentangling the effects of conformational stability and active-site accessibility on activity. Different immobilization methods involve distinct trade-off between these effects, thus emphasizing the need for a holistic (systems) view of immobilized enzymes for the rational development of practical biocatalysts.
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Affiliation(s)
- Juan M Bolivar
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010 Graz, Austria; Austrian Centre of Industrial Biotechnology, Petersgasse 12, A-8010 Graz, Austria; Chemical and Materials Engineering Department, Complutense University of Madrid, 28040 Madrid, Spain
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010 Graz, Austria; Austrian Centre of Industrial Biotechnology, Petersgasse 12, A-8010 Graz, Austria.
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20
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Faulón Marruecos D, Saleh LS, Kim HH, Bryant SJ, Schwartz DK, Kaar JL. Stabilization of Fibronectin by Random Copolymer Brushes Inhibits Macrophage Activation. ACS APPLIED BIO MATERIALS 2019; 2:4698-4702. [DOI: 10.1021/acsabm.9b00815] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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21
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Thompson CJ, Vu VH, Leckband DE, Schwartz DK. Cadherin Extracellular Domain Clustering in the Absence of Trans-Interactions. J Phys Chem Lett 2019; 10:4528-4534. [PMID: 31335147 PMCID: PMC6815682 DOI: 10.1021/acs.jpclett.9b01500] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
While both cis and trans (adhesive)-interactions cooperate in the assembly of intercellular adhesions, computational simulations have predicted that two-dimensional confinement may promote cis-oligomerization, in the absence of trans-interactions. Here, single-molecule tracking of cadherin extracellular domains on supported lipid bilayers revealed the density-dependent formation of oligomers and cis-clusters in the absence of trans-interactions. Lateral oligomers were virtually eliminated by mutating a putative cis (lateral) binding interface. At low cadherin surface coverage, wild-type and mutant cadherin diffused rapidly, consistent with the motion of a lipid molecule within a cadherin-free supported bilayer and with cadherins diffusing as monomers. Although the diffusion of mutant cadherin did not change appreciably with increasing surface coverage, the average short-time diffusion coefficient of wild-type cadherin slowed significantly above a fractional surface coverage of ∼0.01 (∼1100 molecules/μm2). A detailed analysis of molecular trajectories suggested the presence of a broad size distribution of cis-cadherin oligomers. These findings verify predictions that two-dimensional confinement promotes cis-oligomerization, in the absence of trans-interactions.
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Affiliation(s)
- Connor J. Thompson
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder 80309, Colorado, United States
| | - Vinh H. Vu
- Department of Biochemistry, University of Illinois, Urbana–Champaign, Urbana 61801, Illinois, United States
| | - Deborah E. Leckband
- Department of Biochemistry, University of Illinois, Urbana–Champaign, Urbana 61801, Illinois, United States
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana–Champaign, Urbana 61801, Illinois, United States
| | - Daniel K. Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder 80309, Colorado, United States
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22
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Michalek L, Mundsinger K, Barner L, Barner-Kowollik C. Quantifying Solvent Effects on Polymer Surface Grafting. ACS Macro Lett 2019; 8:800-805. [PMID: 35619509 DOI: 10.1021/acsmacrolett.9b00336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
When grafting polymers onto surfaces, the reaction conditions critically influence the resulting interface properties, including the grafting density and molar mass distribution (MMD) on the surface. Herein, we show theoretically and experimentally that the application of poor solvents is beneficial for the "grafting-to" approach. We demonstrate the effect by grafting poly(methyl methacrylate) chains on silica nanoparticles in different solvents and compare the MMD of the polymer in solution before and after grafting via size exclusion chromatography (SEC). The shorter polymer chains are preferentially grafted onto the surface, leading to a distortion effect between the MMD in solution and on surfaces. The molecular weight distortion effect is significantly higher for ethyl acetate (good solvent quality, difference in Mw surface to solution 14%) than for N,N-dimethylacetamide (poor solvent quality, 6%). The difference in MMD on the surface to the solution significantly affects both the surface properties (e.g. the grafting densities) and their determination.
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Affiliation(s)
- Lukas Michalek
- School of Chemistry, Physics and Mechanical Engineering, Institute for Future Environments, Queensland University of Technology (QUT), 2 George Street, QLD 4000, Brisbane, Australia
| | - Kai Mundsinger
- School of Chemistry, Physics and Mechanical Engineering, Institute for Future Environments, Queensland University of Technology (QUT), 2 George Street, QLD 4000, Brisbane, Australia
| | - Leonie Barner
- School of Chemistry, Physics and Mechanical Engineering, Institute for Future Environments, Queensland University of Technology (QUT), 2 George Street, QLD 4000, Brisbane, Australia
- Institut für Biologische Grenzflächen (IBG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Christopher Barner-Kowollik
- School of Chemistry, Physics and Mechanical Engineering, Institute for Future Environments, Queensland University of Technology (QUT), 2 George Street, QLD 4000, Brisbane, Australia
- Macromolecular Architectures, Institut für Technische Chemie und Polymerchemie (ITCP), Karlsruhe Institute of Technology (KIT), Engesserstrasse 18, 76128 Karlsruhe, Germany
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23
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24
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Weltz JS, Kienle DF, Schwartz DK, Kaar JL. Dramatic Increase in Catalytic Performance of Immobilized Lipases by Their Stabilization on Polymer Brush Supports. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01176] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- James S. Weltz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel F. Kienle
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel K. Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Joel L. Kaar
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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25
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Kienle DF, Schwartz DK. Complex Salt Dependence of Polymer Diffusion in Polyelectrolyte Multilayers. J Phys Chem Lett 2019; 10:987-992. [PMID: 30768907 DOI: 10.1021/acs.jpclett.9b00004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Polyelectrolyte multilayers (PEMs) have significant potential in many technologies, yet the dynamics of the constituent polymer chains remains poorly understood. We used total internal reflection fluorescence microscopy to observe microscopic single-molecule transport of fluorescently labeled poly-l-lysine (PLL) diffusing within the bulk of a PEM composed of PLL and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) when exposed to NaCl solutions ranging in concentration from 0 to 2 M. Statistical analysis of PLL trajectories revealed motion that was nonergodic, subdiffusive, and temporally anticorrelated under all conditions. In contrast with previous macroscopic measurements of polymer diffusion within PEMs, the microscopic diffusion was 2-3 orders of magnitude faster and varied nonmonotonically with salt concentration in a way that was similar to trends previously associated with PEM swelling and viscoelastic properties. This trend in the anomalous diffusion was attributed to complex salt-dependent changes in the viscoelastic properties of the film that balanced intermolecular binding and molecular conformation.
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Affiliation(s)
- Daniel F Kienle
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
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26
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Pidhatika B, Nalam PC. Investigation of design parameters in generating antifouling and lubricating surfaces using hydrophilic polymer brushes. J Appl Polym Sci 2019. [DOI: 10.1002/app.47659] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bidhari Pidhatika
- Laboratory for Surface Science and Technology, Department of MaterialsETH Zürich Vladimir‐Prelog‐Weg 1‐5/10, 8093, Zurich Switzerland
| | - Prathima C. Nalam
- Laboratory for Surface Science and Technology, Department of MaterialsETH Zürich Vladimir‐Prelog‐Weg 1‐5/10, 8093, Zurich Switzerland
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27
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Niu Q, Wang D. Probing the polymer anomalous dynamics at solid/liquid interfaces at the single-molecule level. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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28
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Morgese G, Gombert Y, Ramakrishna SN, Benetti EM. Mixing Poly(ethylene glycol) and Poly(2-alkyl-2-oxazoline)s Enhances Hydration and Viscoelasticity of Polymer Brushes and Determines Their Nanotribological and Antifouling Properties. ACS APPLIED MATERIALS & INTERFACES 2018; 10:41839-41848. [PMID: 30395432 DOI: 10.1021/acsami.8b17193] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Poly(2-alkyl-2-oxazoline)s (PAOXAs) have progressively emerged as suitable alternatives for replacing poly(ethylene glycol) (PEG) in a variety of biomaterial-related applications, especially in the designing of polymer brush-based biointerfaces because of their stealth properties and chemical robustness. When equimolar mixtures of PEG and PAOXAs are assembled on surfaces to yield mixed polymer brushes, the interfacial physicochemical properties of the obtained films are significantly altered, in some cases, surpassing the biopassive and lubricious characteristics displayed by single-component PAOXA and PEG counterparts. With a combination of variable angle spectroscopic ellipsometry, quartz crystal microbalance with dissipation, and atomic force microscopy-based methods, we demonstrate that mixing of PEG brushes with equimolar amounts of PAOXA grafts determines an increment in film's hydration and viscoelasticity. In the case of mixtures of PEG and poly(2-methyl-2-oxazoline) or poly(2-ethyl-2-oxazoline), brushes displaying full inertness toward serum proteins and improved lubricity with respect to the corresponding single-component layers can be generated, while providing a multifunctional surface that substantially enlarges the applicability of the designed coatings.
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Affiliation(s)
- Giulia Morgese
- Polymer Surfaces Group, Laboratory for Surface Science and Technology, Department of Materials , ETH Zürich CH 8093 , Zürich , Switzerland
| | - Yvonne Gombert
- Polymer Surfaces Group, Laboratory for Surface Science and Technology, Department of Materials , ETH Zürich CH 8093 , Zürich , Switzerland
| | - Shivaprakash N Ramakrishna
- Polymer Surfaces Group, Laboratory for Surface Science and Technology, Department of Materials , ETH Zürich CH 8093 , Zürich , Switzerland
| | - Edmondo M Benetti
- Polymer Surfaces Group, Laboratory for Surface Science and Technology, Department of Materials , ETH Zürich CH 8093 , Zürich , Switzerland
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29
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30
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Coceancigh H, Higgins DA, Ito T. Optical Microscopic Techniques for Synthetic Polymer Characterization. Anal Chem 2018; 91:405-424. [PMID: 30350610 DOI: 10.1021/acs.analchem.8b04694] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Herman Coceancigh
- Department of Chemistry , Kansas State University , 213 CBC Building , Manhattan , Kansas 66506-0401 , United States
| | - Daniel A Higgins
- Department of Chemistry , Kansas State University , 213 CBC Building , Manhattan , Kansas 66506-0401 , United States
| | - Takashi Ito
- Department of Chemistry , Kansas State University , 213 CBC Building , Manhattan , Kansas 66506-0401 , United States
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31
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Kienle DF, Falatach RM, Kaar JL, Schwartz DK. Correlating Structural and Functional Heterogeneity of Immobilized Enzymes. ACS NANO 2018; 12:8091-8103. [PMID: 30067333 DOI: 10.1021/acsnano.8b02956] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Many nanobiotechnology applications rely on stable and efficient integration of functional biomacromolecules with synthetic nanomaterials. Unfortunately, the reasons for the ubiquitous loss of activity of immobilized enzymes remain poorly understood due to the difficulty in distinguishing between distinct molecular-level mechanisms. Here, we employ complementary single-molecule fluorescence methods that independently measure the impact of immobilization on the structure and function ( i. e., substrate binding kinetics) of nitroreductase (NfsB). Stochastic statistical modeling methods were used to unambiguously quantify the effects of immobilized NfsB structural dynamics on function, allowing us to explicitly separate effects due to conformation and accessibility. Interestingly, we found that nonspecifically tethered NfsB exhibited enhanced stability compared to site-specifically tethered NfsB; however, the folded state of site-specifically tethered NfsB had faster substrate binding rates, suggesting improved active site accessibility. This demonstrated an unexpected intrinsic trade-off associated with competing bioconjugation methods, suggesting that it may be necessary to balance conformational stability versus active site accessibility. This nuanced view of the impact of immobilization will facilitate a rational approach to the integration of enzymes with synthetic nanomaterials.
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Affiliation(s)
- Daniel F Kienle
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Rebecca M Falatach
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Joel L Kaar
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
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32
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Chaparro Sosa AF, Kienle DF, Falatach RM, Flanagan J, Kaar JL, Schwartz DK. Stabilization of Immobilized Enzymes via the Chaperone-Like Activity of Mixed Lipid Bilayers. ACS APPLIED MATERIALS & INTERFACES 2018; 10:19504-19513. [PMID: 29767959 DOI: 10.1021/acsami.8b05523] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Biomimetic lipid bilayers represent intriguing materials for enzyme immobilization, which is critical for many biotechnological applications. Here, through the creation of mixed lipid bilayers, the retention of immobilized enzyme structures and catalytic activity are dramatically enhanced. The enhancement in the retention of enzyme structures, which correlated with an increase in enzyme activity, is observed using dynamic single-molecule (SM) fluorescence methods. The results of SM analysis specifically show that lipid bilayers composed of mixtures of 1,2-dioleoyl- sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl- sn-glycero-3-phospho-(1'- rac-glycerol) (DOPG) stabilize the folded state of nitroreductase (NfsB), increasing the rate of refolding relative to unfolding of enzyme molecules on the bilayer surface. Remarkably, for optimal compositions with 15-50% DOPG, over 95% of NfsB remains folded while the activity of the enzyme is increased as much as 2 times over that in solution. Within this range of DOPG, the strength of the interaction of folded and unfolded NfsB with the bilayer surface was also significantly altered, which was evident by the change in the diffusion of folded and unfolded NfsB in the bilayer. Ultimately, these findings provide direct evidence for the chaperone-like activity of mixed DOPG/DOPC lipid bilayers, which can be controlled by tuning the fraction of DOPG in the bilayer.
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Affiliation(s)
- Andres F Chaparro Sosa
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Daniel F Kienle
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Rebecca M Falatach
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Jessica Flanagan
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Joel L Kaar
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering , University of Colorado , Boulder , Colorado 80309 , United States
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