1
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Ow MJK, Yeow EKL. Revealing the Existence of Long-Range Liquid-Liquid Interfacial Potential in Phase-Transfer Processes. J Phys Chem Lett 2024; 15:6241-6248. [PMID: 38842186 DOI: 10.1021/acs.jpclett.4c01135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
By employing fluorescence wide-field microscopy and a nanoparticle-based phase transfer catalyst (PTC), consisting of a fluorescent silica nanoparticle functionalized with trioctylpropylammonium bromide, we demonstrate that in the presence of NaOH, single nanoparticles display subdiffusive motion along the axis normal to an aqueous liquid-organic liquid interface. This is because of an extended interfacial potential with a shallow well (∼1 kBT) that stretches a few μm into the organic phase, in contrast to previous molecular dynamics studies that reported narrow interfaces on the order of ∼1 nm. Spontaneous interfacial emulsification induced by NaOH results in the propagation of water-in-oil nanoemulsions into the organic solvent that creates an equilibrium hybrid-solvent composition that solvates the PTC. A greater mobility and longer residence time of the PTC at the potential well enhance the interfacial phase transfer process and catalytic efficiency.
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Affiliation(s)
- Matthew J K Ow
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Edwin K L Yeow
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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2
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Diamanti E, López-Gallego F. Single-Particle and Single-Molecule Characterization of Immobilized Enzymes: A Multiscale Path toward Optimizing Heterogeneous Biocatalysts. Angew Chem Int Ed Engl 2024; 63:e202319248. [PMID: 38476019 DOI: 10.1002/anie.202319248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/04/2024] [Accepted: 03/07/2024] [Indexed: 03/14/2024]
Abstract
Heterogeneous biocatalysis is highly relevant in biotechnology as it offers several benefits and practical uses. To leverage the full potential of heterogeneous biocatalysts, the establishment of well-crafted protocols, and a deeper comprehension of enzyme immobilization on solid substrates are essential. These endeavors seek to optimize immobilized biocatalysts, ensuring maximal enzyme performance within confined spaces. For this aim, multidimensional characterization of heterogeneous biocatalysts is required. In this context, spectroscopic and microscopic methodologies conducted at different space and temporal scales can inform about the intraparticle enzyme kinetics, the enzyme spatial distribution, and the mass transport issues. In this Minireview, we identify enzyme immobilization, enzyme catalysis, and enzyme inactivation as the three main processes for which advanced characterization tools unveil fundamental information. Recent advances in operando characterization of immobilized enzymes at the single-particle (SP) and single-molecule (SM) levels inform about their functional properties, unlocking the full potential of heterogeneous biocatalysis toward biotechnological applications.
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Affiliation(s)
- Eleftheria Diamanti
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE)-, Basque Research and Technology Alliance (BRTA), Paseo Miramón, 194, 20014, Donostia-San Sebastián, Spain
| | - Fernando López-Gallego
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE)-, Basque Research and Technology Alliance (BRTA), Paseo Miramón, 194, 20014, Donostia-San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao, Spain
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3
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Grebenkov DS. Diffusion-Controlled Reactions: An Overview. Molecules 2023; 28:7570. [PMID: 38005291 PMCID: PMC10674959 DOI: 10.3390/molecules28227570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/20/2023] [Accepted: 10/21/2023] [Indexed: 11/26/2023] Open
Abstract
We review the milestones in the century-long development of the theory of diffusion-controlled reactions. Starting from the seminal work by von Smoluchowski, who recognized the importance of diffusion in chemical reactions, we discuss perfect and imperfect surface reactions, their microscopic origins, and the underlying mathematical framework. Single-molecule reaction schemes, anomalous bulk diffusions, reversible binding/unbinding kinetics, and many other extensions are presented. An alternative encounter-based approach to diffusion-controlled reactions is introduced, with emphasis on its advantages and potential applications. Some open problems and future perspectives are outlined.
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Affiliation(s)
- Denis S Grebenkov
- Laboratoire de Physique de la Matière Condensée, CNRS-Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
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4
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Meleties M, Martineau RL, Gupta MK, Montclare JK. Particle-Based Microrheology As a Tool for Characterizing Protein-Based Materials. ACS Biomater Sci Eng 2022; 8:2747-2763. [PMID: 35678203 DOI: 10.1021/acsbiomaterials.2c00035] [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: 11/28/2022]
Abstract
Microrheology based on video microscopy of embedded tracer particles has the potential to be used for high-throughput protein-based materials characterization. This potential is due to a number of characteristics of the techniques, including the suitability for measurement of low sample volumes, noninvasive and noncontact measurements, and the ability to set up a large number of samples for facile, sequential measurement. In addition to characterization of the bulk rheological properties of proteins in solution, for example, viscosity, microrheology can provide insight into the dynamics and self-assembly of protein-based materials as well as heterogeneities in the microenvironment being probed. Specifically, passive microrheology in the form of multiple particle tracking and differential dynamic microscopy holds promise for applications in high-throughput characterization because of the lack of user interaction required while making measurements. Herein, recent developments in the use of multiple particle tracking and differential dynamic microscopy are reviewed for protein characterization and their potential to be applied in a high-throughput, automatable setting.
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Affiliation(s)
- Michael Meleties
- Department of Chemical and Biomolecular Engineering, Tandon School of Engineering, New York University, New York, New York 11201, United States
| | - Rhett L Martineau
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States.,Biological and Nanoscale Technologies Division, UES Inc., Dayton, Ohio 45432, United States
| | - Maneesh K Gupta
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
| | - Jin Kim Montclare
- Department of Chemical and Biomolecular Engineering, Tandon School of Engineering, New York University, New York, New York 11201, United States.,Department of Radiology, New York University Langone Health, New York, New York 10016, United States.,Department of Biomaterials, College of Dentistry, New York University, New York, New York 10010, United States.,Department of Chemistry, New York University, New York, New York 10003, United States
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5
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Varela-Moreira A, van Leur H, Krijgsman D, Ecker V, Braun M, Buchner M, H.A.M. Fens M, Hennink WE, Schiffelers RM. Utilizing In Vitro Drug Release Assays to Predict In Vivo Retention of Micelles. Int J Pharm 2022; 618:121638. [DOI: 10.1016/j.ijpharm.2022.121638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 10/18/2022]
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6
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Chen Z, Wei W, Peng H, Jiang H, Xiong B, Zhu J. Revealing the dynamic adsorption and diffusion of peptide amphiphile on supported lipid bilayer by single molecule experiment and simulation. Colloids Surf B Biointerfaces 2021; 204:111809. [PMID: 33965750 DOI: 10.1016/j.colsurfb.2021.111809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 10/21/2022]
Abstract
Dynamic adsorption and diffusion of peptide amphiphiles (PAs) with different numbers of alkyl tails on supported lipid bilayers (SLBs) were investigated by single molecule tracking experiment and molecule dynamic simulation. Experimental results show two distinct populations of PAs with different residence time. Residence time of adsorbed PAs increases with the increase of the alkyl tails, whereas diffusion coefficient monotonically decreases with rising the number of alkyl tails and also decreases with increasing the mobility of SLBs. All-atom molecule dynamic simulation results prove that the adsorption and diffusion of PAs on SLB surface are mainly determined by interactions between PAs and SLBs and also the intrinsic mobility of PAs in aqueous solution. The electrostatic interactions and the mobility of PAs are two dominated but contradictory coefficients for the adsorption and diffusion of PAs. By increasing the alkyl tails, the mobility of PAs decreases while the electrostatic property does not change significantly, resulting in the increase of residence time and decrease of diffusivity of PAs. Additionally, for the PAs with large number of alkyl tails (≥ 3 alkyl tails), steric hindrance of alkyl tails leads to the decrease of adsorption probability of PAs on SLB surface. These findings lay the groundwork for guiding the design of PAs with high cell affinity, potentially useful for efficient drug delivery.
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Affiliation(s)
- Zhenxian Chen
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Wei Wei
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Haiyan Peng
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Hao Jiang
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.
| | - Bijin Xiong
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.
| | - Jintao Zhu
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
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7
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Armstrong MJ, Rodriguez JB, Dahl P, Salamon P, Hess H, Katira P. Power Law Behavior in Protein Desorption Kinetics Originating from Sequential Binding and Unbinding. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13527-13534. [PMID: 33152250 DOI: 10.1021/acs.langmuir.0c02260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The study of protein adsorption at the single molecule level has recently revealed that the adsorption is reversible, but with a long-tailed residence time distribution which can be approximated with a sum of exponential functions putatively related to distinct adsorption sites. Here it is proposed that the shape of the residence time distribution results from an adsorption process with sequential and reversible steps that contribute to overall binding strength resembling "zippering". In this model, the survival function of the residence time distribution of single proteins varies from an exponential distribution for a single adsorption step to a power law distribution with exponent -1/2 for a large number of adsorption steps. The adsorption of fluorescently labeled fibrinogen to glass surfaces is experimentally studied with single molecule imaging. The experimental residence time distribution can be readily fit by the proposed model. This demonstrates that the observed long residence times can arise from stepwise adsorption rather than rare but strong binding sites and provides guidance for the control of protein adsorption to biomaterials.
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Affiliation(s)
- Megan J Armstrong
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States
| | - Juan B Rodriguez
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States
| | - Peter Dahl
- Department of Mechanical Engineering, San Diego State University, San Diego, California 98182, United States
| | - Peter Salamon
- Department of Mathematics and Statistics and Viral Information Institute, San Diego State University, San Diego, California 98182, United States
| | - Henry Hess
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States
| | - Parag Katira
- Department of Mechanical Engineering, San Diego State University, San Diego, California 98182, United States
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8
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Firkowska-Boden I, Helbing C, Dauben TJ, Pieper M, Jandt KD. How Nanotopography-Induced Conformational Changes of Fibrinogen Affect Platelet Adhesion and Activation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11573-11580. [PMID: 32921061 DOI: 10.1021/acs.langmuir.0c02094] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The conformational state of adsorbed human plasma fibrinogen (HPF) has been recognized as the determinant factor in platelet adhesion and thrombus formation on blood-contacting biomaterials. Studies have highlighted the ability to control the HPF conformation merely by tailoring surface nanotopographical features. However, a clear relationship between the conformational changes of adsorbed HPF and the degree of platelet adhesion and activation achieved with different surface nanotopographies is still unclear. Here, we examined HPF assembly characteristics on nanostructured polybutene-1 (PB-1) surfaces with nanosized lamellar crystals (LCs), needle-like crystals (NLCs), and a nanostructured high-density polyethylene (HDPE) surface with shish-kebab crystals (SKCs), at a biologically relevant HPF concentration. By exposing the nanostructured surfaces with preadsorbed HPF to human platelets, significant differences in platelet response on LCs/SKCs and NLCs were identified. The former presented a uniform monolayer in the advanced stage of activation, whereas the latter exhibited minimal adhesion and the early stage of activation. Distinct platelet response was related to the postadsorption conformational changes in HPF, which were confirmed by topography-dependent shifts of the amide I band in attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis. Supported by atomic force microscopy (AFM) characterization, we propose that the mechanism behind the nanotopography-induced HPF conformation is driven by the interplay between the aspect ratios of polymeric crystals and HPF. From the biomedical perspective, our work reveals that surface structuring in a nanoscale size regime can provide a fine-tuning mechanism to manipulate HPF conformation, which can be exploited for the design of thromboresistant biomaterials surfaces.
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Affiliation(s)
- Izabela Firkowska-Boden
- Chair of Materials Science, Otto Schott Institute of Materials Research, Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Christian Helbing
- Chair of Materials Science, Otto Schott Institute of Materials Research, Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Thomas J Dauben
- Chair of Materials Science, Otto Schott Institute of Materials Research, Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Maja Pieper
- Chair of Materials Science, Otto Schott Institute of Materials Research, Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Klaus D Jandt
- Chair of Materials Science, Otto Schott Institute of Materials Research, Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
- Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany
- Jena School for Microbial Communication (JSMC), Neugasse 23, 07743 Jena, Germany
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9
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Xiong B, Chen Z, Yin X, Wang Y, Jiang H, Zhu J. Diffusion behavior of peptide amphiphiles containing different numbers of alkyl tails at a hydrophobic solid-liquid interface: single molecule tracking investigation. SOFT MATTER 2020; 16:4444-4450. [PMID: 32323701 DOI: 10.1039/d0sm00447b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Using the single molecule tracking technique, the diffusion behavior of peptide amphiphiles (PAs) with different numbers of alkyl tails at a hydrophobic solid-liquid interface has been investigated. The effect of the number of alkyl tails of PAs on molecular trajectories at the hydrophobic solid-liquid interface has been systematically studied. PA molecules display an intermittent motion consisting of immobilization and hopping processes, which has been well simulated by the continuous time random walk (CTRW) model. The results reveal that the hydrophobic interaction between the PAs and hydrophobic surface plays an important role in the diffusion behavior of PAs. Increasing the number of alkyl tails in PAs systematically reduces the mobility of PAs on the hydrophobic surface. Moreover, the diffusion behavior of PAs at the hydrophobic interface also shows pH dependence. A decrease in pH is beneficial to the motion of all PAs on the hydrophobic surface, which can be ascribed to the protonation of PAs in acidic solutions. Therefore, the hydrophobic interaction is crucial to the transport of peptide amphiphiles at hydrophobic interfaces which would be important for the design of peptides in biological applications.
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Affiliation(s)
- Bijin Xiong
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
| | - Zhenxian Chen
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
| | - Xiaoyan Yin
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
| | - Yingying Wang
- School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China
| | - Hao Jiang
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
| | - Jintao Zhu
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage (HUST) of Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
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10
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Dutta S, Ghosh M, Karmakar R, Chakrabarti J. Dynamic signature of ligand binding over a protein surface. Phys Rev E 2019; 100:062411. [PMID: 31962438 DOI: 10.1103/physreve.100.062411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Indexed: 06/10/2023]
Abstract
We study the motion of Zn^{2+} in the presence of ubiquitin by all-atom molecular-dynamics simulations. We observe that unlike normal diffusive liquid, metal ions show an exponential tail in the self-van Hove function (self-vHf). Moreover, the metal ions are trapped strongly by acidic residues which form a binding pocket over the protein surface. The exponential tail disappears by mutation of trapping residues, suggesting that the tail appears due to trapped motion of the ions. The mean-squared displacements, however, in all the cases show linear dependence on time. Our model establishes that ligand binding generically results in an exponential tail of self-vHf. The self-vHf may give an approach to find binding pockets over a protein surface.
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Affiliation(s)
- Sutapa Dutta
- Department of Chemical, Biological and Macro-Molecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
| | - Mahua Ghosh
- Department of Chemical, Biological and Macro-Molecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
| | - Rahul Karmakar
- Department of Chemical, Biological and Macro-Molecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
| | - J Chakrabarti
- Department of Chemical, Biological and Macro-Molecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
- Thematic Unit of Excellence on Computational Materials Science, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
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11
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Hou R, Willumeit-Römer R, Garamus VM, Frant M, Koll J, Feyerabend F. Adsorption of Proteins on Degradable Magnesium-Which Factors are Relevant? ACS APPLIED MATERIALS & INTERFACES 2018; 10:42175-42185. [PMID: 30433751 DOI: 10.1021/acsami.8b17507] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Although the adsorption of proteins on the Mg surface was ascribed to be the main reason for the effect of proteins on magnesium (Mg) degradation, few studies about the adsorption of proteins on the Mg surface were performed due to the labile circumstances during immersion. In the present study, the adsorption of bovine serum albumin (BSA) and fibrinogen (Fib) on the Mg surface during and after immersion was extensively investigated in different media for the first time. The results revealed that BSA and Fib showed a similar adsorption trend on the Mg surface during and after immersion, and they adsorbed more on the Mg surface in Hank's balanced salt solution (HBSS) than in Dulbecco's modified Eagle medium Glutamax-I (DMEM). The possible influence factors for protein adsorption, such as pH, surface roughness, and wettability, were considered to elucidate different adsorption in HBSS and DMEM. It was found that the participation of Ca2+ in the formation of degradation products largely affected the degradation rate of Mg, changed surface roughness, compactness, and surface charge during immersion, which largely suppressed the adsorption of proteins on the Mg surface.
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Affiliation(s)
| | | | | | - Marion Frant
- Department of Biomaterials , Institute for Bioprocessing and Analytical Measurement Techniques , Rosenhof , D-37308 Heiligenstadt , Germany
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12
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Zhang X, Firkowska-Boden I, Arras MML, Kastantin MJ, Helbing C, Özogul A, Gnecco E, Schwartz DK, Jandt KD. Nanoconfinement and Sansetsukon-like Nanocrawling Govern Fibrinogen Dynamics and Self-Assembly on Nanostructured Polymeric Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:14309-14316. [PMID: 30354162 DOI: 10.1021/acs.langmuir.8b02917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Surface nanostructures are increasingly more employed for controlled protein assembly on functional nanodevices, in nanobiotechnology, and in nanobiomaterials. However, the mechanism and dynamics of how nanostructures induce order in the adsorbed protein assemblies are still enigmatic. Here, we use single-molecule mapping by accumulated probe trajectories and complementary atomic force microscopy to shed light on the dynamic of in situ assembly of human plasma fibrinogen (HPF) adsorbed on nanostructured polybutene-1 (PB-1) and nanostructured polyethylene (PE) surfaces. We found a distinct lateral heterogeneity of HPF-polymer nanostructure interface (surface occupancy, residence time, and diffusion coefficient) that allow identifying the interplay between protein topographical nanoconfinement, protein diffusion mechanism, and ordered protein self-assembly. The protein diffusion analysis revealed high-diffusion polarization without correlation to the anisotropic friction characteristic of the polymer surfaces. This suggests that HPF molecules confined on the nanosized PB-1 needle crystals and PE shish-kebab crystals, respectively, undergo partial detachment and diffuse via a Sansetsukon-like nanocrawling mechanism. This mechanism is based on the intrinsic flexibility of HPF in the coiled-coil regions. We conclude that nanostructured surfaces that encourage this characteristic surface mobility are more likely to lead to the formation of ordered protein assemblies and may be useful for advanced nanobiomaterials.
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Affiliation(s)
| | | | - Matthias M L Arras
- Large Scale Structures Group, Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Mark J Kastantin
- 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
| | - Klaus D Jandt
- Jena Center for Soft Matter (JCSM) , Friedrich Schiller University Jena , Philosophenweg 7 , 07743 Jena , Germany
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13
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Yang M, Wang K, Lin J, Wang L, Wei F, Zhu J, Zheng W, Shen L. Gel Phase Membrane Retards Amyloid β-Peptide (1-42) Fibrillation by Restricting Slaved Diffusion of Peptides on Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8408-8414. [PMID: 29925241 DOI: 10.1021/acs.langmuir.8b01315] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Plasma membranes in the human brain can interact with amyloid β-peptide (1-42; Aβ42) and induce Aβ42 fibrillation, which is considered to be a crucial process underlying the neurotoxicity of Aβ42 and the pathogenesis of Alzheimer's disease (AD). However, the mechanism of membrane-mediated Aβ42 fibrillation at the molecular level remains elusive. Here we study the role of adsorbed Aβ42 peptides on membrane-mediated fibrillation using supported lipid bilayers of varying phase structures (gel and fluid). Using total internal reflection fluorescence microscopy and interfacial specific second-order nonlinear optical spectroscopy, we show that the dynamics of 2D-mobile Aβ42 molecules, facilitated by the highly mobile lipids underneath the peptides, are critical to Aβ42 fibrillation on liquid phase membranes. This growth mechanism is retarded on gel phase membranes where the dynamics of 2D-mobile peptides are restricted by the "frozen" lipids with less mobility.
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Affiliation(s)
- Mengting Yang
- School of Chemistry and Chemical Engineering , Huazhong University of Science and Technology , Wuhan 430070 , China
| | - Kang Wang
- School of Chemistry, Chemical Engineering and Life Science , Wuhan University of Technology , Wuhan 430074 , China
| | - Jiake Lin
- School of Chemistry, Chemical Engineering and Life Science , Wuhan University of Technology , Wuhan 430074 , China
| | - Liqun Wang
- Institute for Interdisciplinary Research & Key Laboratory of Optoelectronic Chemical Materials and Devices of Education , Jianghan University , Wuhan 430056 , China
| | - Feng Wei
- Institute for Interdisciplinary Research & Key Laboratory of Optoelectronic Chemical Materials and Devices of Education , Jianghan University , Wuhan 430056 , China
| | - Jintao Zhu
- School of Chemistry and Chemical Engineering , Huazhong University of Science and Technology , Wuhan 430070 , China
| | - Wanquan Zheng
- Institute for Interdisciplinary Research & Key Laboratory of Optoelectronic Chemical Materials and Devices of Education , Jianghan University , Wuhan 430056 , China
- Institute des Sciences Moléculaires d'Orsay, Université Paris-Sud , 91405 Orsay Cedex , France
| | - Lei Shen
- School of Chemistry, Chemical Engineering and Life Science , Wuhan University of Technology , Wuhan 430074 , China
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14
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Moringo NA, Shen H, Tauzin LJ, Wang W, Bishop LDC, Landes CF. Variable Lysozyme Transport Dynamics on Oxidatively Functionalized Polystyrene Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10818-10828. [PMID: 28937222 DOI: 10.1021/acs.langmuir.7b02641] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Tuning protein adsorption dynamics at polymeric interfaces is of great interest to many biomedical and material applications. Functionalization of polymer surfaces is a common method to introduce application-specific surface chemistries to a polymer interface. In this work, single-molecule fluorescence microscopy is utilized to determine the adsorption dynamics of lysozyme, a well-studied antibacterial protein, at the interface of polystyrene oxidized via UV exposure and oxygen plasma and functionalized by ligand grafting to produce varying degrees of surface hydrophilicity, surface roughness, and induced oxygen content. Single-molecule tracking indicates lysozyme loading capacities, and surface mobility at the polymer interface is hindered as a result of all functionalization techniques. Adsorption dynamics of lysozyme depend on the extent and the specificity of the oxygen functionalities introduced to the polystyrene surface. Hindered adsorption and mobility are dominated by hydrophobic effects attributed to water hydration layer formation at the functionalized polystyrene surfaces.
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Affiliation(s)
- Nicholas A Moringo
- Department of Chemistry, ‡Department of Electrical and Computer Engineering, and §Smalley-Curl Institute, Rice University , Houston, Texas 77251, United States
| | - Hao Shen
- Department of Chemistry, ‡Department of Electrical and Computer Engineering, and §Smalley-Curl Institute, Rice University , Houston, Texas 77251, United States
| | - Lawrence J Tauzin
- Department of Chemistry, ‡Department of Electrical and Computer Engineering, and §Smalley-Curl Institute, Rice University , Houston, Texas 77251, United States
| | - Wenxiao Wang
- Department of Chemistry, ‡Department of Electrical and Computer Engineering, and §Smalley-Curl Institute, Rice University , Houston, Texas 77251, United States
| | - Logan D C Bishop
- Department of Chemistry, ‡Department of Electrical and Computer Engineering, and §Smalley-Curl Institute, Rice University , Houston, Texas 77251, United States
| | - Christy F Landes
- Department of Chemistry, ‡Department of Electrical and Computer Engineering, and §Smalley-Curl Institute, Rice University , Houston, Texas 77251, United States
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15
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Lupo KM, Hinton DA, Ng JD, Padilla NA, Goldsmith RH. Probing Heterogeneity and Bonding at Silica Surfaces through Single-Molecule Investigation of Base-Mediated Linkage Failure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9171-9179. [PMID: 27541852 DOI: 10.1021/acs.langmuir.6b02456] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The nature of silica surfaces is relevant to many chemical systems, including heterogeneous catalysis and chromatographies utilizing functionalized-silica stationary phases. Surface linkages must be robust to achieve wide and reliable applicability. However, silyl ether-silica support linkages are known to be susceptible to detachment when exposed to basic conditions. We use single-molecule spectroscopy to examine the rate of surface linkage failure upon exposure to base at a variety of deposition conditions. Kinetic analysis elucidates the role of thermal annealing and addition of blocking layers in increasing stability. Critically, it was found that successful surface modification strategies alter the rate at which base molecules approach the silica surface as opposed to reducing surface linkage reactivity. Our results also demonstrate that the innate structural diversity of the silica surface is likely the cause of observed heterogeneity in surface-linkage disruption kinetics.
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Affiliation(s)
- Katherine M Lupo
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Daniel A Hinton
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - James D Ng
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Nicolas A Padilla
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Randall H Goldsmith
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
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16
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Salipante PF, Hudson SD. Reversible Adsorption Kinetics of Near Surface Dimer Colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8565-8573. [PMID: 27483023 PMCID: PMC5064446 DOI: 10.1021/acs.langmuir.6b02019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We investigate the effect of shape on reversible adsorption kinetics using colloidal polystyrene dimers near a solid glass surface as a model system. The interaction between colloid and wall is tuned using electrostatic, depletion, and gravity forces to produce a double-well potential. The dwell time in each of the potential wells is measured from long duration particle trajectories. The height of each monomer relative to the glass surface is measured to a resolution of <20 nm by in-line holographic microscopy. The measured transition probability distributions are used in kinetic equations to describe the flux of particles to and from the surface. The dimers are compared to independent isolated monomers to determine the effects of shape on adsorption equilibria and kinetics. To elucidate these differences, we consider both mass and surface coverage and two definitions of surface coverage. The results show that dimers with single coverage produce slower adsorption, lower surface coverage, and higher mass coverage in comparison to those of monomers, while dimers with double coverage adsorb faster and result in higher surface coverage.
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17
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Wei L, Ye Z, Luo W, Chen B, Xiao L. Redistribution of fluorescent molecules at the solid/liquid interface with total internal reflection illumination. Talanta 2016; 155:229-34. [PMID: 27216678 DOI: 10.1016/j.talanta.2016.04.023] [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: 01/01/2016] [Revised: 04/06/2016] [Accepted: 04/09/2016] [Indexed: 10/21/2022]
Abstract
Many intriguing physical and chemical processes commonly take place at the solid/liquid interface. Total internal reflection illumination, together with single molecule spectroscopy, provides a robust platform for the selective exploration of kinetic processes close the interface. With these techniques, it was observed that the distribution of Rhodamine B molecules close to a solid/liquid interface could be regulated in a photo-induced route. The laser-induced repulsion force at this interface is enough to compromise the Brownian diffusion of single molecules in a range of several hundred nanometers normal to the solid/liquid interface. This observation is fundamentally and practically interesting because moderate laser intensity is enough to initiate this repulsion effect. Therefore, it might display extensive applications in the development of photo-modulation technique with high throughput capability.
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Affiliation(s)
- Lin Wei
- Dynamic Optical Microscopic Imaging Laboratory, Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, PR China
| | - Zhongju Ye
- Dynamic Optical Microscopic Imaging Laboratory, Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, PR China
| | - Wenjuan Luo
- Dynamic Optical Microscopic Imaging Laboratory, Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, PR China
| | - Bo Chen
- Dynamic Optical Microscopic Imaging Laboratory, Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, PR China
| | - Lehui Xiao
- Dynamic Optical Microscopic Imaging Laboratory, Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, PR China.
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18
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Wang D, Chin HY, He C, Stoykovich MP, Schwartz DK. Polymer Surface Transport Is a Combination of in-Plane Diffusion and Desorption-Mediated Flights. ACS Macro Lett 2016; 5:509-514. [PMID: 35607234 DOI: 10.1021/acsmacrolett.6b00183] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies of polymer motion at solid/liquid interfaces described the transport in the context of a continuous time random walk (CTRW) process, in which diffusion switches between desorption-mediated "flights" (i.e., hopping) and surface-adsorbed waiting-time intervals. However, it has been unclear whether the waiting times represented periods of complete immobility or times during which molecules engaged in a different (e.g., slower or confined) mode of interfacial transport. Here we designed high-throughput, single-molecule tracking measurements to address this question. Specifically, we studied polymer dynamics on either chemically homogeneous or nanopatterned surfaces (hexagonal diblock copolymer films) with chemically distinct domains, where polymers were essentially excluded from the low-affinity domains, eliminating the possibility of significant continuous diffusion in the absence of desorption-mediated flights. Indeed, the step-size distributions on homogeneous surfaces exhibited an additional diffusive mode that was missing on the chemically heterogeneous nanopatterned surfaces, confirming the presence of a slow continuous mode due to 2D in-plane diffusion. Kinetic Monte Carlo simulations were performed to test this model and, with the theoretical in-plane diffusion coefficient of D2D = 0.20 μm2/s, we found a good agreement between simulations and experimental data on both chemically homogeneous and nanopatterned surfaces.
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Affiliation(s)
- Dapeng Wang
- Department of Chemical and
Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Huai-Ying Chin
- Department of Chemical and
Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Chunlin He
- Department of Chemical and
Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Mark P. Stoykovich
- 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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19
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Augmenting drug-carrier compatibility improves tumour nanotherapy efficacy. Nat Commun 2016; 7:11221. [PMID: 27071376 PMCID: PMC4833858 DOI: 10.1038/ncomms11221] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/03/2016] [Indexed: 12/11/2022] Open
Abstract
A major goal of cancer nanotherapy is to use nanoparticles as carriers for targeted delivery of anti-tumour agents. The drug-carrier association after intravenous administration is essential for efficient drug delivery to the tumour. However, a large number of currently available nanocarriers are self-assembled nanoparticles whose drug-loading stability is critically affected by the in vivo environment. Here we used in vivo FRET imaging to systematically investigate how drug-carrier compatibility affects drug release in a tumour mouse model. We found the drug's hydrophobicity and miscibility with the nanoparticles are two independent key parameters that determine its accumulation in the tumour. Next, we applied these findings to improve chemotherapeutic delivery by augmenting the parent drug's compatibility; as a result, we achieved better antitumour efficacy. Our results help elucidate nanomedicines' in vivo fate and provide guidelines for efficient drug delivery.
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20
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Ng JD, Upadhyay SP, Marquard AN, Lupo KM, Hinton DA, Padilla NA, Bates DM, Goldsmith RH. Single-Molecule Investigation of Initiation Dynamics of an Organometallic Catalyst. J Am Chem Soc 2016; 138:3876-83. [PMID: 26944030 DOI: 10.1021/jacs.6b00357] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The action of molecular catalysts comprises multiple microscopic kinetic steps whose nature is of central importance in determining catalyst activity and selectivity. Single-molecule microscopy enables the direct examination of these steps, including elucidation of molecule-to-molecule variability. Such molecular diversity is particularly important for the behavior of molecular catalysts supported at surfaces. We present the first combined investigation of the initiation dynamics of an operational palladium cross-coupling catalyst at the bulk and single-molecule levels, including under turnover conditions. Base-initiated kinetics reveal highly heterogeneous behavior indicative of diverse catalyst population. Unexpectedly, this distribution becomes more heterogeneous at increasing base concentration. We model this behavior with a two-step saturation mechanism and identify specific microscopic steps where chemical variability must exist in order to yield observed behavior. Critically, we reveal how structural diversity at a surface translates into heterogeneity in catalyst behavior, while demonstrating how single-molecule experiments can contribute to understanding of molecular catalysts.
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Affiliation(s)
- James D Ng
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Sunil P Upadhyay
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Angela N Marquard
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Katherine M Lupo
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Daniel A Hinton
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Nicolas A Padilla
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Desiree M Bates
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Randall H Goldsmith
- Department of Chemistry, The University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
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21
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Kovrigina EA, Kovrigin EL. Fluorescence of Supported Phospholipid Bilayers Recorded in a Conventional Horizontal-Beam Spectrofluorometer. J Fluoresc 2015; 26:379-83. [PMID: 26662810 DOI: 10.1007/s10895-015-1743-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/07/2015] [Indexed: 12/17/2022]
Abstract
Supported phospholipid bilayers are a convenient model of cellular membranes in studies of membrane biophysics and protein-lipid interactions. Traditionally, supported lipid bilayers are formed on a flat surface of a glass slide to be observed through fluorescence microscopes. This paper describes a method to enable fluorescence detection from the supported lipid bilayers using standard horizontal-beam spectrofluorometers instead of the microscopes. In the proposed approach, the supported lipid bilayers are formed on the inner optical surfaces of the standard fluorescence microcell. To enable observation of the bilayer absorbed on the cell wall, the microcell is placed in a standard fluorometer cell holder and specifically oriented to expose the inner cell walls to both excitation and emission channels with a help of the custom cell adaptor. The signal intensity from supported bilayers doped with 1 % (mol) of rhodamine-labeled lipid in the standard 3-mm optical microcell was equivalent to fluorescence of the 70-80 nM reference solution of rhodamine recorded in a commercial microcell adaptor. Because no modifications to the instruments are required in this method, a variety of steady-state and time-domain fluorescence measurements of the supported phospholipid bilayers may be performed with the spectral resolution using standard horizontal-beam spectrofluorometers.
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Affiliation(s)
| | - Evgenii L Kovrigin
- Chemistry Department, Marquette University, PO Box 1881, Milwaukee, WI, 53201, USA.
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22
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Gerhardt A, Mcumber AC, Nguyen BH, Lewus R, Schwartz DK, Carpenter JF, Randolph TW. Surfactant Effects on Particle Generation in Antibody Formulations in Pre-filled Syringes. J Pharm Sci 2015; 104:4056-4064. [PMID: 26413998 DOI: 10.1002/jps.24654] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 12/15/2022]
Abstract
Protein aggregation and particle formation have been observed when protein solutions contact hydrophobic interfaces, and it has been suggested that this undesirable phenomenon may be initiated by interfacial adsorption and subsequent gelation of the protein. The addition of surfactants, such as polysorbate 20, to protein formulations has been proposed as a way to reduce protein adsorption at silicone oil-water interfaces and mitigate the production of aggregates and particles. In an accelerated stability study, monoclonal antibody formulations containing varying concentrations of polysorbate 20 were incubated and agitated in pre-filled glass syringes (PFS), exposing the protein to silicone oil-water interfaces at the siliconized syringe walls, air-water interfaces, and agitation stress. Following agitation in siliconized syringes that contained an air bubble, lower particle concentrations were measured in the surfactant-containing antibody formulations than in surfactant-free formulations. Polysorbate 20 reduced particle formation when added at concentrations above or below the critical micelle concentration (CMC). The ability of polysorbate 20 to decrease particle generation in PFS corresponded with its ability to inhibit gelation of the adsorbed protein layer, which was assessed by measuring the interfacial diffusion of individual antibody molecules at the silicone oil-water interface using total internal reflectance fluorescence (TIRF) microscopy with single-molecule tracking.
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Affiliation(s)
- Alana Gerhardt
- Department of Chemical and Biological Engineering, University of Colorado-Boulder, Boulder, Colorado
| | - Aaron C Mcumber
- Department of Chemical and Biological Engineering, University of Colorado-Boulder, Boulder, Colorado
| | - Bao H Nguyen
- Department of Chemical and Biological Engineering, University of Colorado-Boulder, Boulder, Colorado
| | - Rachael Lewus
- Formulation Sciences Department, MedImmune, Gaithersburg, Maryland
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado-Boulder, Boulder, Colorado
| | - John F Carpenter
- Department of Pharmaceutical Sciences, University of Colorado-Denver, Aurora, Colorado
| | - Theodore W Randolph
- Department of Chemical and Biological Engineering, University of Colorado-Boulder, Boulder, Colorado.
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23
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Hasnain S, Bandyopadhyay P. An analytical correlated random walk model and its application to understand subdiffusion in crowded environment. J Chem Phys 2015; 143:114104. [PMID: 26395684 DOI: 10.1063/1.4930275] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Subdiffusion in crowded environment such as movement of macromolecule in a living cell has often been observed experimentally. The primary reason for subdiffusion is volume exclusion by the crowder molecules. However, other effects such as hydrodynamic interaction may also play an important role. Although there are a large number of computer simulation studies on understanding molecular crowding, there is a lack of theoretical models that can be connected to both experiment and simulation. In the current work, we have formulated a one-dimensional correlated random walk model by connecting this to the motion in a crowded environment. We have found the exact solution of the probability distribution function of the model by solving it analytically. The parameters of our model can be obtained either from simulation or experiment. It has been shown that this analytical model captures some of the general features of diffusion in crowded environment as given in the previous literature and its prediction for transient subdiffusion closely matches the observations of a previous study of computer simulation of Escherichia coli cytoplasm. It is likely that this model will open up more development of theoretical models in this area.
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Affiliation(s)
- Sabeeha Hasnain
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Pradipta Bandyopadhyay
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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24
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McUmber AC, Randolph TW, Schwartz DK. Electrostatic Interactions Influence Protein Adsorption (but Not Desorption) at the Silica-Aqueous Interface. J Phys Chem Lett 2015; 6:2583-7. [PMID: 26266737 DOI: 10.1021/acs.jpclett.5b00933] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
High-throughput single-molecule total internal reflection fluorescence microscopy was used to investigate the effects of pH and ionic strength on bovine serum albumin (BSA) adsorption, desorption, and interfacial diffusion at the aqueous-fused silica interface. At high pH and low ionic strength, negatively charged BSA adsorbed slowly to the negatively charged fused silica surface. At low pH and low ionic strength, where BSA was positively charged, or in solutions at higher ionic strength, adsorption was approximately 1000 times faster. Interestingly, neither surface residence times nor the interfacial diffusion coefficients of BSA were influenced by pH or ionic strength. These findings suggested that adsorption kinetics were dominated by energy barriers associated with electrostatic interactions, but once adsorbed, protein-surface interactions were dominated by short-range nonelectrostatic interactions. These results highlight the ability of single-molecule techniques to isolate elementary processes (e.g., adsorption and desorption) under steady-state conditions, which would be impossible to measure using ensemble-averaging methods.
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Affiliation(s)
- Aaron C McUmber
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Theodore W Randolph
- 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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25
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Higgins DA, Park SC, Tran-Ba KH, Ito T. Single-Molecule Investigations of Morphology and Mass Transport Dynamics in Nanostructured Materials. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2015; 8:193-216. [PMID: 26132347 DOI: 10.1146/annurev-anchem-071114-040153] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nanostructured materials such as mesoporous metal oxides and phase-separated block copolymers form the basis for new monolith, membrane, and thin film technologies having applications in energy storage, chemical catalysis, and separations. Mass transport plays an integral role in governing the application-specific performance characteristics of many such materials. The majority of methods employed in their characterization provide only ensemble data, often masking the nanoscale, molecular-level details of materials morphology and mass transport. Single-molecule fluorescence methods offer direct routes to probing these characteristics on a single-molecule/single-nanostructure basis. This article provides a review of single-molecule studies focused on measurements of anisotropic diffusion, adsorption, partitioning, and confinement in nanostructured materials. Experimental methods covered include confocal and wide-field fluorescence microscopy. The results obtained promise to deepen our understanding of mass transport mechanisms in nanostructures, thus aiding in the realization of advanced materials systems.
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Affiliation(s)
- Daniel A Higgins
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401; ,
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26
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McUmber AC, Larson NR, Randolph TW, Schwartz DK. Molecular trajectories provide signatures of protein clustering and crowding at the oil/water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5882-5890. [PMID: 25950404 DOI: 10.1021/acs.langmuir.5b00984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using high throughput single-molecule total internal reflection fluorescence microscopy (TIRFM), we have acquired molecular trajectories of bovine serum albumin (BSA) and hen egg white lysozyme during protein layer formation at the silicone oil-water interface. These trajectories were analyzed to determine the distribution of molecular diffusion coefficients, and for signatures of molecular crowding/caging, including subdiffusive motion and temporal anticorrelation of the instantaneous velocity vector. The evolution of these properties with aging time of the interface was compared with dynamic interfacial tension measurements. For both lysozyme and BSA, we observed an overall slowing of protein objects, the onset of both subdiffusive and anticorrelated motion (associated with crowding), and a decrease in the interfacial tension with aging time. For lysozyme, all of these phenomena occurred virtually simultaneously, consistent with a homogeneous model of layer formation that involves gradual crowding of weakly interacting proteins. For BSA, however, the slowing occurred first, followed by the signatures of crowding/caging, followed by a decrease in interfacial tension, consistent with a heterogeneous model of layer formation involving the formation of protein clusters. The application of microrheological methods to single molecule trajectories described here provides an unprecedented level of mechanistic interpretation of interfacial events that occurred over a wide range of interfacial protein coverage.
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Affiliation(s)
- Aaron C McUmber
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Nicholas R Larson
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Theodore W Randolph
- 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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27
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Popov P, Steinkerchner L, Mann EK. Molecular dynamics study of rhodamine 6G diffusion at n-decane-water interfaces. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:053308. [PMID: 26066280 DOI: 10.1103/physreve.91.053308] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Indexed: 06/04/2023]
Abstract
Two-dimensional diffusion of a rhodamine 6G fluorescent tracer molecule at the n-decane-water interface was studied with all-atom molecular dynamics simulations. In agreement with experimental data, we find increased mobility of the tracer at the n-decane-water interfaces in comparison to its mobility in bulk water. Orientational ordering of water and n-decane molecules near the interface is observed, and may change the interfacial viscosity as suggested to explain the experimental data. However, the restricted rotational motion of the rhodamine molecule at the interface suggests that the Saffman-Delbrück model may be a more appropriate approximation of rhodamine diffusion at n-decane-water interfaces, and, without any decrease in interfacial viscosity, suggests faster diffusion consistent with both experimental and simulation values.
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Affiliation(s)
- Piotr Popov
- Physics Department, Kent State University, Kent, Ohio, USA, 44242
| | - Leo Steinkerchner
- Physics Department, Kent State University, Kent, Ohio, USA, 44242
- Wadsworth High School, Wadsworth, Ohio, USA, 44281
| | - Elizabeth K Mann
- Physics Department, Kent State University, Kent, Ohio, USA, 44242
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28
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Salipante PF, Hudson SD. A colloid model system for interfacial sorption kinetics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3368-3376. [PMID: 25714416 DOI: 10.1021/la504821y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Particle adsorption to an interface may be a complicated affair, motivating detailed measurements of various processes involved, to discover better understanding of the role of particle characteristics and solution conditions on adsorption coverage and rate. Here we use micron size colloids with a weak interfacial interaction potential as a model system to track particle motion and measure the rates of desorption and adsorption. The colloid-interface interaction strength is tuned to be less than 10 kBT so that it is comparable to many nanoscale systems of interest such as proteins at interfaces. The tuning is accomplished using a combination of depletion, electrostatic, and gravitational forces. The colloids transition between an entropically trapped adsorbed state and a desorbed state through Brownian motion. Observations are made using an light-emitting diode (LED)-based total internal reflection microscopy (TIRM) setup. The observed adsorption and desorption rates are compared to theoretical predictions based on the measured interaction potential and near-wall particle diffusivity. The results demonstrate that diffusion dynamics play a significant role when the barrier energy is small. This experimental system will allow for the future study of more complex dynamics such as nonspherical colloids and collective effects at higher concentrations.
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Affiliation(s)
- Paul F Salipante
- Polymers and Complex Fluids Group, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Steven D Hudson
- Polymers and Complex Fluids Group, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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29
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Langdon BB, Mirhossaini RB, Mabry JN, Sriram I, Lajmi A, Zhang Y, Rojas OJ, Schwartz DK. Single-molecule resolution of protein dynamics on polymeric membrane surfaces: the roles of spatial and population heterogeneity. ACS APPLIED MATERIALS & INTERFACES 2015; 7:3607-3617. [PMID: 25611782 DOI: 10.1021/am507730k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Although polymeric membranes are widely used in the purification of protein pharmaceuticals, interactions between biomolecules and membrane surfaces can lead to reduced membrane performance and damage to the product. In this study, single-molecule fluorescence microscopy provided direct observation of bovine serum albumin (BSA) and human monoclonal antibody (IgG) dynamics at the interface between aqueous buffer and polymeric membrane materials including regenerated cellulose and unmodified poly(ether sulfone) (PES) blended with either polyvinylpyrrolidone (PVP), polyvinyl acetate-co-polyvinylpyrrolidone (PVAc-PVP), or polyethylene glycol methacrylate (PEGM) before casting. These polymer surfaces were compared with model surfaces composed of hydrophilic bare fused silica and hydrophobic trimethylsilane-coated fused silica. At extremely dilute protein concentrations (10(-3)-10(-7) mg/mL), protein surface exchange was highly dynamic with protein monomers desorbing from the surface within ∼1 s after adsorption. Protein oligomers (e.g., nonspecific dimers, trimers, or larger aggregates), although less common, remained on the surface for 5 times longer than monomers. Using newly developed super-resolution methods, we could localize adsorption sites with ∼50 nm resolution and quantify the spatial heterogeneity of the various surfaces. On a small anomalous subset of the adsorption sites, proteins adsorbed preferentially and tended to reside for significantly longer times (i.e., on "strong" sites). Proteins resided for shorter times overall on surfaces that were more homogeneous and exhibited fewer strong sites (e.g., PVAc-PVP/PES). We propose that strong surface sites may nucleate protein aggregation, initiated preferentially by protein oligomers, and accelerate ultrafiltration membrane fouling. At high protein concentrations (0.3-1.0 mg/mL), fewer strong adsorption sites were observed, and surface residence times were reduced. This suggests that at high concentrations, adsorbed proteins block strong sites from further protein adsorption. Importantly, this demonstrates that strong binding sites can be modified by changing solution conditions. Membrane surfaces are intrinsically heterogeneous; by employing single-molecule techniques, we have provided a new framework for understanding protein interactions with such surfaces.
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Affiliation(s)
- Blake B Langdon
- Department of Chemical and Biological Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States
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30
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Affiliation(s)
- Lydia Kisley
- Department of Chemistry and Department of Electrical and Computer
Engineering,
Rice Quantum Institute, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
| | - Christy F. Landes
- Department of Chemistry and Department of Electrical and Computer
Engineering,
Rice Quantum Institute, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
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31
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Robben KC, Tran-Ba KH, Ito T, Higgins DA. Trajectory-Profile-Guided Single Molecule Tracking for Assignment of One-Dimensional Diffusion Trajectories. Anal Chem 2014; 86:10820-7. [DOI: 10.1021/ac502881u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Kevin C. Robben
- Department of Chemistry, Kansas State University, 213
CBC Building, Manhattan, Kansas 66506-0401, United States
| | - Khanh-Hoa Tran-Ba
- 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
| | - Daniel A. Higgins
- Department of Chemistry, Kansas State University, 213
CBC Building, Manhattan, Kansas 66506-0401, United States
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32
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Tauzin L, Shuang B, Kisley L, Mansur AP, Chen J, de Leon A, Advincula RC, Landes CF. Charge-dependent transport switching of single molecular ions in a weak polyelectrolyte multilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8391-9. [PMID: 24960617 PMCID: PMC4216201 DOI: 10.1021/la5012007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The tunable nature of weak polyelectrolyte multilayers makes them ideal candidates for drug loading and delivery, water filtration, and separations, yet the lateral transport of charged molecules in these systems remains largely unexplored at the single molecule level. We report the direct measurement of the charge-dependent, pH-tunable, multimodal interaction of single charged molecules with a weak polyelectrolyte multilayer thin film, a 10 bilayer film of poly(acrylic acid) and poly(allylamine hydrochloride) PAA/PAH. Using fluorescence microscopy and single-molecule tracking, two modes of interaction were detected: (1) adsorption, characterized by the molecule remaining immobilized in a subresolution region and (2) diffusion trajectories characteristic of hopping (D ∼ 10(-9) cm(2)/s). Radius of gyration evolution analysis and comparison with simulated trajectories confirmed the coexistence of the two transport modes in the same single molecule trajectories. A mechanistic explanation for the probe and condition mediated dynamics is proposed based on a combination of electrostatics and a reversible, pH-induced alteration of the nanoscopic structure of the film. Our results are in good agreement with ensemble studies conducted on similar films, confirm a previously-unobserved hopping mechanism for charged molecules in polyelectrolyte multilayers, and demonstrate that single molecule spectroscopy can offer mechanistic insight into the role of electrostatics and nanoscale tunability of transport in weak polyelectrolyte multilayers.
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Affiliation(s)
- Lawrence
J. Tauzin
- Department
of Chemistry and Department of Electrical and Chemical Engineering, Rice University, Houston, Texas 77251, United States
| | - Bo Shuang
- Department
of Chemistry and Department of Electrical and Chemical Engineering, Rice University, Houston, Texas 77251, United States
| | - Lydia Kisley
- Department
of Chemistry and Department of Electrical and Chemical Engineering, Rice University, Houston, Texas 77251, United States
| | - Andrea P. Mansur
- Department
of Chemistry and Department of Electrical and Chemical Engineering, Rice University, Houston, Texas 77251, United States
| | - Jixin Chen
- Department
of Chemistry and Department of Electrical and Chemical Engineering, Rice University, Houston, Texas 77251, United States
| | - Al de Leon
- Department
of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Rigoberto C. Advincula
- Department
of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Christy F. Landes
- Department
of Chemistry and Department of Electrical and Chemical Engineering, Rice University, Houston, Texas 77251, United States
- E-mail:
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33
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Xu D, He Y, Yeung ES. Direct Observation of the Orientation Dynamics of Single Protein-Coated Nanoparticles at Liquid/Solid Interfaces. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201400025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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34
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Xu D, He Y, Yeung ES. Direct Observation of the Orientation Dynamics of Single Protein-Coated Nanoparticles at Liquid/Solid Interfaces. Angew Chem Int Ed Engl 2014; 53:6951-5. [DOI: 10.1002/anie.201400025] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 04/09/2014] [Indexed: 12/28/2022]
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35
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Kastantin M, Langdon BB, Schwartz DK. A bottom-up approach to understanding protein layer formation at solid-liquid interfaces. Adv Colloid Interface Sci 2014; 207:240-52. [PMID: 24484895 PMCID: PMC4028386 DOI: 10.1016/j.cis.2013.12.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 12/05/2013] [Accepted: 12/17/2013] [Indexed: 11/25/2022]
Abstract
A common goal across different fields (e.g. separations, biosensors, biomaterials, pharmaceuticals) is to understand how protein behavior at solid-liquid interfaces is affected by environmental conditions. Temperature, pH, ionic strength, and the chemical and physical properties of the solid surface, among many factors, can control microscopic protein dynamics (e.g. adsorption, desorption, diffusion, aggregation) that contribute to macroscopic properties like time-dependent total protein surface coverage and protein structure. These relationships are typically studied through a top-down approach in which macroscopic observations are explained using analytical models that are based upon reasonable, but not universally true, simplifying assumptions about microscopic protein dynamics. Conclusions connecting microscopic dynamics to environmental factors can be heavily biased by potentially incorrect assumptions. In contrast, more complicated models avoid several of the common assumptions but require many parameters that have overlapping effects on predictions of macroscopic, average protein properties. Consequently, these models are poorly suited for the top-down approach. Because the sophistication incorporated into these models may ultimately prove essential to understanding interfacial protein behavior, this article proposes a bottom-up approach in which direct observations of microscopic protein dynamics specify parameters in complicated models, which then generate macroscopic predictions to compare with experiment. In this framework, single-molecule tracking has proven capable of making direct measurements of microscopic protein dynamics, but must be complemented by modeling to combine and extrapolate many independent microscopic observations to the macro-scale. The bottom-up approach is expected to better connect environmental factors to macroscopic protein behavior, thereby guiding rational choices that promote desirable protein behaviors.
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Affiliation(s)
- Mark Kastantin
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, United States
| | - Blake B Langdon
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, United States.
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36
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Unified superresolution experiments and stochastic theory provide mechanistic insight into protein ion-exchange adsorptive separations. Proc Natl Acad Sci U S A 2014; 111:2075-80. [PMID: 24459184 DOI: 10.1073/pnas.1318405111] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Chromatographic protein separations, immunoassays, and biosensing all typically involve the adsorption of proteins to surfaces decorated with charged, hydrophobic, or affinity ligands. Despite increasingly widespread use throughout the pharmaceutical industry, mechanistic detail about the interactions of proteins with individual chromatographic adsorbent sites is available only via inference from ensemble measurements such as binding isotherms, calorimetry, and chromatography. In this work, we present the direct superresolution mapping and kinetic characterization of functional sites on ion-exchange ligands based on agarose, a support matrix routinely used in protein chromatography. By quantifying the interactions of single proteins with individual charged ligands, we demonstrate that clusters of charges are necessary to create detectable adsorption sites and that even chemically identical ligands create adsorption sites of varying kinetic properties that depend on steric availability at the interface. Additionally, we relate experimental results to the stochastic theory of chromatography. Simulated elution profiles calculated from the molecular-scale data suggest that, if it were possible to engineer uniform optimal interactions into ion-exchange systems, separation efficiencies could be improved by as much as a factor of five by deliberately exploiting clustered interactions that currently dominate the ion-exchange process only accidentally.
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37
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Chen P, Zhou X, Andoy NM, Han KS, Choudhary E, Zou N, Chen G, Shen H. Spatiotemporal catalytic dynamics within single nanocatalysts revealed by single-molecule microscopy. Chem Soc Rev 2014; 43:1107-17. [DOI: 10.1039/c3cs60215j] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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38
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Langdon BB, Kastantin M, Walder R, Schwartz DK. Interfacial protein-protein associations. Biomacromolecules 2013; 15:66-74. [PMID: 24274729 DOI: 10.1021/bm401302v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
While traditional models of protein adsorption focus primarily on direct protein-surface interactions, recent findings suggest that protein-protein interactions may play a central role. Using high-throughput intermolecular resonance energy transfer (RET) tracking, we directly observed dynamic, protein-protein associations of bovine serum albumin on polyethylene glycol modified surfaces. The associations were heterogeneous and reversible, and associating molecules resided on the surface for longer times. The appearance of three distinct RET states suggested a spatially heterogeneous surface - with areas of high protein density (i.e., strongly interacting clusters) coexisting with mobile monomers. Distinct association states exhibited characteristic behavior, i.e., partial-RET (monomer-monomer) associations were shorter-lived than complete-RET (protein-cluster) associations. While the fractional surface area covered by regions with high protein density (i.e., clusters) increased with increasing concentration, the distribution of contact times between monomers and clusters was independent of solution concentration, suggesting that associations were a local phenomenon, and independent of the global surface coverage.
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Affiliation(s)
- Blake B Langdon
- Department of Chemical and Biological Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States
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39
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Single-molecule resolution of protein structure and interfacial dynamics on biomaterial surfaces. Proc Natl Acad Sci U S A 2013; 110:19396-401. [PMID: 24235137 DOI: 10.1073/pnas.1311761110] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A method was developed to monitor dynamic changes in protein structure and interfacial behavior on surfaces by single-molecule Förster resonance energy transfer. This method entails the incorporation of unnatural amino acids to site-specifically label proteins with single-molecule Förster resonance energy transfer probes for high-throughput dynamic fluorescence tracking microscopy on surfaces. Structural changes in the enzyme organophosphorus hydrolase (OPH) were monitored upon adsorption to fused silica (FS) surfaces in the presence of BSA on a molecule-by-molecule basis. Analysis of >30,000 individual trajectories enabled the observation of heterogeneities in the kinetics of surface-induced OPH unfolding with unprecedented resolution. In particular, two distinct pathways were observed: a majority population (∼ 85%) unfolded with a characteristic time scale of 0.10 s, and the remainder unfolded more slowly with a time scale of 0.7 s. Importantly, even after unfolding, OPH readily desorbed from FS surfaces, challenging the common notion that surface-induced unfolding leads to irreversible protein binding. This suggests that protein fouling of surfaces is a highly dynamic process because of subtle differences in the adsorption/desorption rates of folded and unfolded species. Moreover, such observations imply that surfaces may act as a source of unfolded (i.e., aggregation-prone) protein back into solution. Continuing study of other proteins and surfaces will examine whether these conclusions are general or specific to OPH in contact with FS. Ultimately, this method, which is widely applicable to virtually any protein, provides the framework to develop surfaces and surface modifications with improved biocompatibility.
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40
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Chen J, Bremauntz A, Kisley L, Shuang B, Landes CF. Super-resolution mbPAINT for optical localization of single-stranded DNA. ACS APPLIED MATERIALS & INTERFACES 2013; 5:9338-43. [PMID: 24073628 PMCID: PMC3934010 DOI: 10.1021/am403984k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate the application of superlocalization microscopy to identify sequence-specific portions of single-stranded DNA (ssDNA) with sequence resolution of 50 nucleotides, corresponding to a spatial resolution of 30 nm. Super-resolution imaging was achieved using a variation of a single-molecule localization method, termed as "motion blur" point accumulation for imaging in nanoscale topography (mbPAINT). The target ssDNA molecules were immobilized on the substrate. Short, dye-labeled, and complementary ssDNA molecules stochastically bound to the target ssDNA, with repeated binding events allowing super-resolution. Sequence specificity was demonstrated via the use of a control, noncomplementary probe. The results support the possibility of employing relatively inexpensive short ssDNAs to identify gene sequence specificity with improved resolution in comparison to the existing methods.
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Affiliation(s)
- Jixin Chen
- Department of Chemistry, Rice University, Houston, TX, 77251-1892, USA
| | - Alberto Bremauntz
- Department of Chemistry, Rice University, Houston, TX, 77251-1892, USA
| | - Lydia Kisley
- Department of Chemistry, Rice University, Houston, TX, 77251-1892, USA
| | - Bo Shuang
- Department of Chemistry, Rice University, Houston, TX, 77251-1892, USA
| | - Christy F. Landes
- Department of Chemistry, Rice University, Houston, TX, 77251-1892, USA
- Department of Electrical and Computer Engineering, Rice University, Houston, TX, 77251-1892, USA
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41
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Skaug MJ, Mabry J, Schwartz DK. Intermittent molecular hopping at the solid-liquid interface. PHYSICAL REVIEW LETTERS 2013; 110:256101. [PMID: 23829747 DOI: 10.1103/physrevlett.110.256101] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Indexed: 05/10/2023]
Abstract
The mobility of molecules on a solid surface plays a key role in diverse phenomena such as friction and self-assembly and in surface-based technologies like heterogeneous catalysis and molecular targeting. To understand and control these surface processes, a universally applicable model of surface transport at solid-liquid interfaces is needed. However, unlike diffusion at a solid-gas interface, little is known about the mechanisms of diffusion at a solid-liquid interface. Using single-molecule tracking at a solid-liquid interface, we found that a diverse set of molecules underwent intermittent random walks with non-Gaussian displacements. This contrasts with the normal random walk and Gaussian statistics that are commonly assumed for molecular surface diffusion. The molecules became temporarily immobilized for random waiting times between surface displacements produced by excursions through the bulk fluid. A common power-law distribution of waiting times indicated a spectrum of binding energies. We propose that intermittent hopping is universal to molecular surface diffusion at a solid-liquid interface.
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Affiliation(s)
- Michael J Skaug
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA
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42
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Shuang B, Byers CP, Kisley L, Wang LY, Zhao J, Morimura H, Link S, Landes CF. Improved analysis for determining diffusion coefficients from short, single-molecule trajectories with photoblinking. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:228-34. [PMID: 23215347 PMCID: PMC3648847 DOI: 10.1021/la304063j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Two maximum likelihood estimation (MLE) methods were developed for optimizing the analysis of single-molecule trajectories that include phenomena such as experimental noise, photoblinking, photobleaching, and translation or rotation out of the collection plane. In particular, short, single-molecule trajectories with photoblinking were studied, and our method was compared to existing analytical techniques applied to simulated data. The optimal method for various experimental cases was established, and the optimized MLE method was applied to a real experimental system: single-molecule diffusion of fluorescent molecular machines known as nanocars.
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Affiliation(s)
- Bo Shuang
- Department of Chemistry and Rice Quantum Institute, Rice University, Houston, Texas 77251-1892, United States
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43
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Kastantin M, Schwartz DK. Identifying multiple populations from single-molecule lifetime distributions. Chemphyschem 2012; 14:374-80. [PMID: 23255328 DOI: 10.1002/cphc.201200838] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Indexed: 12/14/2022]
Abstract
A major advantage of single-molecule methods over ensemble-averaging techniques involves the ability to characterize heterogeneity through the identification of multiple molecular populations. It can be challenging, however, to determine absolute values of dynamic parameters (and to relate these values to those determined from a conventional method) because characteristic timescales of various populations may vary over many orders of magnitude, and under a given set of experimental conditions instrumental sensitivity to various populations may be unequal. Using data obtained from the single-molecule tracking microscopy of fibrinogen protein adsorption and desorption, it is shown that by performing a combined analysis of molecular trajectories obtained using a range of acquisition times, it is possible to extract quantitative absolute values of multiple population fractions and residence times (with well-defined uncertainties), even when these values span many orders of magnitude. In particular, as many as six distinct populations are rigorously identified, exhibiting characteristic timescales that vary over nearly three orders of magnitude with population fractions as small as one part in a thousand. This approach will lead to better comparability between single-molecule experiments and may be useful in connecting single-molecule to ensemble-averaged observations.
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Affiliation(s)
- Mark Kastantin
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, 80309, USA
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