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Schnitzler LG, Baumgartner K, Kolb A, Braun B, Westerhausen C. Acetylcholinesterase Activity Influenced by Lipid Membrane Area and Surface Acoustic Waves. MICROMACHINES 2022; 13:mi13020287. [PMID: 35208411 PMCID: PMC8877910 DOI: 10.3390/mi13020287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 12/10/2022]
Abstract
According to the current model of nerve propagation, the function of acetylcholinesterase (AChE) is to terminate synaptic transmission of nerve signals by hydrolyzing the neurotransmitter acetylcholine (ACh) in the synaptic cleft to acetic acid (acetate) and choline. However, extra-synaptic roles, which are known as ‘non-classical’ roles, have not been fully elucidated. Here, we measured AChE activity with the enzyme bound to lipid membranes of varying area per enzyme in vitro using the Ellman assay. We found that the activity was not affected by density fluctuations in a supported lipid bilayer (SLB) induced by standing surface acoustic waves. Nevertheless, we found twice as high activity in the presence of small unilamellar vesicles (SUV) compared to lipid-free samples. We also showed that the increase in activity scaled with the available membrane area per enzyme.
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Affiliation(s)
- Lukas G. Schnitzler
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, 80799 Munich, Germany
| | - Kathrin Baumgartner
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, 80799 Munich, Germany
- Physiology, Institute of Theoretical Medicine, University of Augsburg, 86159 Augsburg, Germany
| | - Anna Kolb
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
| | - Benedikt Braun
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
| | - Christoph Westerhausen
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, 80799 Munich, Germany
- Physiology, Institute of Theoretical Medicine, University of Augsburg, 86159 Augsburg, Germany
- Augsburg Center for Innovative Technologies (ACIT), 86159 Augsburg, Germany
- Correspondence:
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Rizvi A, Mulvey JT, Patterson JP. Observation of Liquid-Liquid-Phase Separation and Vesicle Spreading during Supported Bilayer Formation via Liquid-Phase Transmission Electron Microscopy. NANO LETTERS 2021; 21:10325-10332. [PMID: 34890211 DOI: 10.1021/acs.nanolett.1c03556] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Liquid-phase transmission electron microscopy (LP-TEM) enables the real-time visualization of nanoscale dynamics in solution. This technique has been used to study the formation and transformation mechanisms of organic and inorganic nanomaterials. Here, we study the formation of block-copolymer-supported bilayers using LP-TEM. We observe two formation pathways that involve either liquid droplets or vesicles as intermediates toward supported bilayers. Quantitative image analysis methods are used to characterize vesicle spread rates and show the origin of defect formation in supported bilayers. Our results suggest that bilayer assembly methods that proceed via liquid droplet intermediates should be beneficial for forming pristine supported bilayers. Furthermore, supported bilayers inside the liquid cells may be used to image membrane interactions with proteins and nanoparticles in the future.
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Affiliation(s)
- Aoon Rizvi
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Justin T Mulvey
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Joseph P Patterson
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697-2025, United States
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Barani A, Paktinat H, Janmaleki M, Mohammadi A, Mosaddegh P, Fadaei-Tehrani A, Sanati-Nezhad A. Microfluidic integrated acoustic waving for manipulation of cells and molecules. Biosens Bioelectron 2016; 85:714-725. [DOI: 10.1016/j.bios.2016.05.059] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 05/13/2016] [Accepted: 05/19/2016] [Indexed: 12/28/2022]
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Hu SK, Huang LT, Chao L. Membrane species mobility under in-lipid-membrane forced convection. SOFT MATTER 2016; 12:6954-6963. [PMID: 27476605 DOI: 10.1039/c6sm01145d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Processing and managing cell membrane proteins for characterization while maintaining their intact structure is challenging. Hydrodynamic flow has been used to transport membrane species in supported lipid bilayers (SLBs) where the hydrophobic cores of the membrane species can be protected during processing. However, the forced convection mechanism of species embedded in lipid bilayers is still unclear. Developing a controlled SLB platform with a practical model to predict the membrane species mobility in the platform under in-lipid-membrane forced convection is imperative to ensure the practical applicability of SLBs in processing and managing membrane species with various geometrical properties. The mobility of membrane species is affected by the driving force from the aqueous environment in addition to the frictions from the lipid bilayer, in which both lipid leaflets may exhibit different speeds relative to that of the moving species. In this study, we developed a model, based on the applied driving force and the possible frictional resistances that the membrane species encounter, to predict how the mobility under in-lipid-membrane forced convection is influenced by the sizes of the species' hydrophilic portion in the aqueous environment and the hydrophobic portion embedded in the membrane. In addition, we used a microfluidic device for controlling the flow to arrange the lipid membrane and the tested membrane species in the desirable locations in order to obtain a SLB platform which can provide clear mobility responses of the species without disturbance from the species dispersion effect. The model predictions were consistent with the experimental observations, with the sliding friction coefficient between the upper leaflet and the hydrophilic portion of the species as the only regressed parameter. The result suggests that not only the lateral drag frictions from the lipid layers but also the sliding frictions between the species and the lipid layer planes could significantly influence the species mobility. The consistency between the experimental results and the model predictions suggests that our model based on lateral drag and sliding frictions between the species and the lipid leaflets can be used to describe the mobility of half-transmembrane species. We also demonstrated the possibility of how the scope of this model can be broadened to describe the mobility of transmembrane proteins extending through both lipid leaflets.
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Affiliation(s)
- Shu-Kai Hu
- Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan.
| | - Ling-Ting Huang
- Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan.
| | - Ling Chao
- Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan.
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Reusch T, Schülein FJR, Nicolas JD, Osterhoff M, Beerlink A, Krenner HJ, Müller M, Wixforth A, Salditt T. Collective lipid bilayer dynamics excited by surface acoustic waves. PHYSICAL REVIEW LETTERS 2014; 113:118102. [PMID: 25260008 DOI: 10.1103/physrevlett.113.118102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Indexed: 06/03/2023]
Abstract
We use standing surface acoustic waves to induce coherent phonons in model lipid multilayers deposited on a piezoelectric surface. Probing the structure by phase-controlled stroboscopic x-ray pulses we find that the internal lipid bilayer electron density profile oscillates in response to the externally driven motion of the lipid film. The structural response to the well-controlled motion is a strong indication that bilayer structure and membrane fluctuations are intrinsically coupled, even though these structural changes are averaged out in equilibrium and time integrating measurements. Here the effects are revealed by a timing scheme with temporal resolution on the picosecond scale in combination with the sub-nm spatial resolution, enabled by high brilliance synchrotron x-ray reflectivity.
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Affiliation(s)
- T Reusch
- Institut für Röntgenphysik, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - F J R Schülein
- Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr. 1, 86159 Augsburg, Germany and Nanosystems Initiative Munich, Schellingstrasse 4, 80799 Munich, Germany
| | - J D Nicolas
- Institut für Röntgenphysik, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - M Osterhoff
- Institut für Röntgenphysik, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - A Beerlink
- Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22605 Hamburg, Germany
| | - H J Krenner
- Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr. 1, 86159 Augsburg, Germany and Nanosystems Initiative Munich, Schellingstrasse 4, 80799 Munich, Germany
| | - M Müller
- Institut für Theoretische Physik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - A Wixforth
- Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr. 1, 86159 Augsburg, Germany and Nanosystems Initiative Munich, Schellingstrasse 4, 80799 Munich, Germany
| | - T Salditt
- Institut für Röntgenphysik, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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Tarbell JM, Shi ZD, Dunn J, Jo H. Fluid Mechanics, Arterial Disease, and Gene Expression. ANNUAL REVIEW OF FLUID MECHANICS 2014; 46:591-614. [PMID: 25360054 DOI: 10.1146/annurev-fluid-010313-141418] [Citation(s) in RCA: 262] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
This review places modern research developments in vascular mechanobiology in the context of hemodynamic phenomena in the cardiovascular system and the discrete localization of vascular disease. The modern origins of this field are traced, beginning in the 1960s when associations between flow characteristics, particularly blood flow-induced wall shear stress, and the localization of atherosclerotic plaques were uncovered, and continuing to fluid shear stress effects on the vascular lining endothelial) cells (ECs), including their effects on EC morphology, biochemical production, and gene expression. The earliest single-gene studies and genome-wide analyses are considered. The final section moves from the ECs lining the vessel wall to the smooth muscle cells and fibroblasts within the wall that are fluid me chanically activated by interstitial flow that imposes shear stresses on their surfaces comparable with those of flowing blood on EC surfaces. Interstitial flow stimulates biochemical production and gene expression, much like blood flow on ECs.
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Affiliation(s)
- John M Tarbell
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031
| | - Zhong-Dong Shi
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065
| | - Jessilyn Dunn
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30322
| | - Hanjoong Jo
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30322
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Ding X, Li P, Lin SCS, Stratton ZS, Nama N, Guo F, Slotcavage D, Mao X, Shi J, Costanzo F, Huang TJ. Surface acoustic wave microfluidics. LAB ON A CHIP 2013; 13:3626-49. [PMID: 23900527 PMCID: PMC3992948 DOI: 10.1039/c3lc50361e] [Citation(s) in RCA: 420] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next.
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Affiliation(s)
- Xiaoyun Ding
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Peng Li
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sz-Chin Steven Lin
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Zackary S. Stratton
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Nitesh Nama
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Feng Guo
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Daniel Slotcavage
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xiaole Mao
- Department of Bioengineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jinjie Shi
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Francesco Costanzo
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Tony Jun Huang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Bioengineering, The Pennsylvania State University, University Park, PA 16802, USA
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Supported Membranes Meet Flat Fluidics: Monitoring Dynamic Cell Adhesion on Pump-Free Microfluidics Chips Functionalized with Supported Membranes Displaying Mannose Domains. MATERIALS 2013; 6:669-681. [PMID: 28809333 PMCID: PMC5452083 DOI: 10.3390/ma6020669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 01/07/2013] [Accepted: 02/05/2013] [Indexed: 01/17/2023]
Abstract
In this paper we demonstrate the combination of supported membranes and so-called flat microfluidics, which enables one to manipulate liquids on flat chip surfaces via “inverse piezoelectric effect”. Here, an alternating external electric field applied to the inter-digital transducers excites a surface acoustic wave on a piezoelectric substrate. Employing lithographic patterning of self-assembled monolayers of alkoxysilanes, we successfully confine a free-standing, hemi-cylindrical channel with the volume of merely 7 µL . The experimentally determined maximum flow velocity scales linearly with the acoustic power, suggesting that our current setup can drive liquids at the speed of up to 7 cm/s (corresponding to a shear rate of 280 s−1) without applying high pressures using a fluidic pump. After the establishment of the functionalization of fluidic chip surfaces with supported membranes, we deposited asymmetric supported membranes displaying well-defined mannose domains and monitored the dynamic adhesion of E. Coli HB101 expressing mannose-binding receptors. Despite of the further technical optimization required for the quantitative analysis, the obtained results demonstrate that the combination of supported membranes and flat fluidics opens a large potential to investigate dynamic adhesion of cells on biofunctional membrane surfaces with the minimum amount of samples, without any fluidic pump.
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10
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Xie Y, Ahmed D, Lapsley MI, Lin SCS, Nawaz AA, Wang L, Huang TJ. Single-shot characterization of enzymatic reaction constants Km and kcat by an acoustic-driven, bubble-based fast micromixer. Anal Chem 2012; 84:7495-501. [PMID: 22880882 PMCID: PMC3991781 DOI: 10.1021/ac301590y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this work we present an acoustofluidic approach for rapid, single-shot characterization of enzymatic reaction constants K(m) and k(cat). The acoustofluidic design involves a bubble anchored in a horseshoe structure which can be stimulated by a piezoelectric transducer to generate vortices in the fluid. The enzyme and substrate can thus be mixed rapidly, within 100 ms, by the vortices to yield the product. Enzymatic reaction constants K(m) and k(cat) can then be obtained from the reaction rate curves for different concentrations of substrate while holding the enzyme concentration constant. We studied the enzymatic reaction for β-galactosidase and its substrate (resorufin-β-D-galactopyranoside) and found K(m) and k(cat) to be 333 ± 130 μM and 64 ± 8 s(-1), respectively, which are in agreement with published data. Our approach is valuable for studying the kinetics of high-speed enzymatic reactions and other chemical reactions.
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Affiliation(s)
- Yuliang Xie
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Daniel Ahmed
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Michael Ian Lapsley
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sz-Chin Steven Lin
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Ahmad Ahsan Nawaz
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Lin Wang
- Ascent Bio-Nano Technologies Inc, State College, PA 16801, USA
| | - Tony Jun Huang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
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11
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Sanderson JM. Resolving the kinetics of lipid, protein and peptide diffusion in membranes. Mol Membr Biol 2012; 29:118-43. [DOI: 10.3109/09687688.2012.678018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Hennig M, Wolff M, Neumann J, Wixforth A, Schneider MF, Rädler JO. DNA concentration modulation on supported lipid bilayers switched by surface acoustic waves. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:14721-14725. [PMID: 22077281 DOI: 10.1021/la203413b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Spatially addressable arrays of molecules embedded in or anchored to supported lipid bilayers are important for on-chip screening and binding assays; however, methods to sort or accumulate components in a fluid membrane on demand are still limited. Here we apply in-plane surface acoustic shear waves (SAWs) to laterally accumulate double-stranded DNA segments electrostatically bound to a cationic supported lipid bilayer. The fluorescently labeled DNA segments are found to segregate into stripe patterns with a spatial frequency corresponding to the periodicity of the standing SAW wave (~10 μm). The DNA molecules are accumulated 10-fold in the regions of SAW antinodes. The superposition of two orthogonal sets of SAW sources creates checkerboard like arrays of DNA demonstrating the potential to generate arrayed fields dynamically. The pattern relaxation time of 0.58 s, which is independent of the segment length, indicates a sorting and relaxation mechanism dominated by lipid diffusion rather than DNA self-diffusion.
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Affiliation(s)
- Martin Hennig
- Center for NanoScience, Ludwig-Maximilians-Universität, Fakultät für Physik, Geschwister Scholl Platz 1, D-80539 München, Germany
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Jönsson P, Gunnarsson A, Höök F. Accumulation and separation of membrane-bound proteins using hydrodynamic forces. Anal Chem 2010; 83:604-11. [PMID: 21155531 DOI: 10.1021/ac102979b] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The separation of molecules residing in the cell membrane remains a largely unsolved problem in the fields of bioscience and biotechnology. We demonstrate how hydrodynamic forces can be used to both accumulate and separate membrane-bound proteins in their native state. A supported lipid bilayer (SLB) was formed inside a microfluidic channel with the two proteins streptavidin (SA) and cholera toxin (CT) coupled to receptors in the lipid bilayer. The anchored proteins were first driven toward the edge of the lipid bilayer by hydrodynamic forces from a flowing liquid above the SLB, resulting in the accumulation of protein molecules at the edge of the bilayer. After the concentration process, the bulk flow of liquid in the channel was reversed and the accumulated proteins were driven away from the edge of the bilayer. Each type of protein was found to move at a characteristic drift velocity, determined by the frictional coupling between the protein and the lipid bilayer, as well as the size and shape of the protein molecule. Despite having a similar molecular weight, SA and CT could be separated into monomolecular populations using this approach. The method also revealed heterogeneity among the CT molecules, resulting in three subpopulations with different drift velocities. This was tentatively attributed to multivalent interactions between the protein and the monosialoganglioside G(M1) receptors in the lipid bilayer.
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Affiliation(s)
- Peter Jönsson
- Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
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Huth M, Hertrich S, Mezo G, Madarasz E, Nickel B. Neural Stem Cell Spreading on Lipid Based Artificial Cell Surfaces, Characterized by Combined X-ray and Neutron Reflectometry. MATERIALS (BASEL, SWITZERLAND) 2010; 3:4994-5006. [PMID: 28883366 PMCID: PMC5445775 DOI: 10.3390/ma3114994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 11/09/2010] [Indexed: 11/16/2022]
Abstract
We developed a bioadhesive coating based on a synthetic peptide-conjugate (AK-cyclo[RGDfC]) which contains multiples of the arginyl-glycyl-aspartic acid (RGD) amino acid sequence. Biotinylated AK-cyclo[RGDfC] is bound to a supported lipid bilayer via a streptavidin interlayer. Layering, hydration and packing of the coating is quantified by X-ray and neutron reflectometry experiments. AK-cyclo[RGDfC] binds to the streptavidin interlayer in a stretched-out on edge configuration. The highly packed configuration with only 12% water content maximizes the number of accessible adhesion sites. Enhanced cell spreading of neural stem cells was observed for AK-cyclo[RGDfC] functionalized bilayers. Due to the large variety of surfaces which can be coated by physisorption of lipid bilayers, this approach is of general interest for the fabrication of biocompatible surfaces.
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Affiliation(s)
- Martin Huth
- Ludwig-Maximilians-Universität, Department für Physik and CeNS, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
| | - Samira Hertrich
- Ludwig-Maximilians-Universität, Department für Physik and CeNS, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
| | - Gabor Mezo
- Research Group of Peptide Chemistry, Hungarian Academy of Science, Eötvös L. University, Pazmany P. stny. 1/A, 1117 Budapest, Hungary.
| | - Emilia Madarasz
- Laboratory of Cellular and Developmental Neurobiology, Institute of Experimental Medicine of Hungarian Academy of Science, Szigony u. 43, Budapest, H-1083, Hungary.
| | - Bert Nickel
- Ludwig-Maximilians-Universität, Department für Physik and CeNS, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
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Neumann J, Hennig M, Wixforth A, Manus S, Rädler JO, Schneider MF. Transport, separation, and accumulation of proteins on supported lipid bilayers. NANO LETTERS 2010; 10:2903-8. [PMID: 20698603 DOI: 10.1021/nl100993r] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Transport, separation, and accumulation of proteins in their natural environment are central goals in protein biotechnology. Miniaturized assays of supported lipid bilayers (SLBs) have been proposed as promising candidates to realize such technology on a chip, but a modular system for the controlled transport of membrane proteins does not exist. In this letter, we demonstrate that standing surface acoustic waves drive the in-plane redistribution of proteins on planar SLBs over macroscopic distances (3.5 mm). Accumulation of proteins in periodic patterns of about 10-fold protein concentration difference is accomplished and shown to relax into the homogeneous state by diffusion. Different proteins separate in individual fractions from a homogeneous distribution and are transported and accumulated into clusters using beats. The modular planar setup has the potential of integrating other lab-on-a-chip tools, for monitoring the membrane-protein integrity or adding microfluidic features for blood screening or DNA analysis.
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Affiliation(s)
- J Neumann
- Center for NanoScience CeNS, Universität Augsburg, Institut für Physik Universitätsstrasse 1, D-86159 Augsburg, Germany
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Shi J, Huang H, Stratton Z, Huang Y, Huang TJ. Continuous particle separation in a microfluidic channel via standing surface acoustic waves (SSAW). LAB ON A CHIP 2009; 9:3354-9. [PMID: 19904400 DOI: 10.1039/b915113c] [Citation(s) in RCA: 274] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This work introduces a method of continuous particle separation through standing surface acoustic wave (SSAW)-induced acoustophoresis in a microfluidic channel. Using this SSAW-based method, particles in a continuous laminar flow can be separated based on their volume, density and compressibility. In this work, a mixture of particles of equal density but dissimilar volumes was injected into a microchannel through two side inlets, sandwiching a deionized water sheath flow injected through a central inlet. A one-dimensional SSAW generated by two parallel interdigital transducers (IDTs) was established across the channel, with the channel spanning a single SSAW pressure node located at the channel center. Application of the SSAW induced larger axial acoustic forces on the particles of larger volume, repositioning them closer to the wave pressure node at the center of the channel. Thus particles were laterally moved to different regions of the channel cross-section based on particle volume. The particle separation method presented here is simple and versatile, capable of separating virtually all kinds of particles (regardless of charge/polarization or optical properties) with high separation efficiency and low power consumption.
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Affiliation(s)
- Jinjie Shi
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
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