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Pick H, Alves AC, Vogel H. Single-Vesicle Assays Using Liposomes and Cell-Derived Vesicles: From Modeling Complex Membrane Processes to Synthetic Biology and Biomedical Applications. Chem Rev 2018; 118:8598-8654. [PMID: 30153012 DOI: 10.1021/acs.chemrev.7b00777] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The plasma membrane is of central importance for defining the closed volume of cells in contradistinction to the extracellular environment. The plasma membrane not only serves as a boundary, but it also mediates the exchange of physical and chemical information between the cell and its environment in order to maintain intra- and intercellular functions. Artificial lipid- and cell-derived membrane vesicles have been used as closed-volume containers, representing the simplest cell model systems to study transmembrane processes and intracellular biochemistry. Classical examples are studies of membrane translocation processes in plasma membrane vesicles and proteoliposomes mediated by transport proteins and ion channels. Liposomes and native membrane vesicles are widely used as model membranes for investigating the binding and bilayer insertion of proteins, the structure and function of membrane proteins, the intramembrane composition and distribution of lipids and proteins, and the intermembrane interactions during exo- and endocytosis. In addition, natural cell-released microvesicles have gained importance for early detection of diseases and for their use as nanoreactors and minimal protocells. Yet, in most studies, ensembles of vesicles have been employed. More recently, new micro- and nanotechnological tools as well as novel developments in both optical and electron microscopy have allowed the isolation and investigation of individual (sub)micrometer-sized vesicles. Such single-vesicle experiments have revealed large heterogeneities in the structure and function of membrane components of single vesicles, which were hidden in ensemble studies. These results have opened enormous possibilities for bioanalysis and biotechnological applications involving unprecedented miniaturization at the nanometer and attoliter range. This review will cover important developments toward single-vesicle analysis and the central discoveries made in this exciting field of research.
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Affiliation(s)
- Horst Pick
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Ana Catarina Alves
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Horst Vogel
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
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2
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XU Y, SUN LL, GAO YJ, QIN WW, PENG TH, LI D. Research Progresses in Single Molecule Enzymology. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2016. [DOI: 10.1016/s1872-2040(16)60957-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Jiménez ZA, Yoshida R. Temperature Driven Self-Assembly of a Zwitterionic Block Copolymer That Exhibits Triple Thermoresponsivity and pH Sensitivity. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00769] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Zulma A. Jiménez
- Department of Materials Engineering,
School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Ryo Yoshida
- Department of Materials Engineering,
School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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4
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Chen P, Keller AM, Joshi CP, Martell DJ, Andoy NM, Benítez JJ, Chen TY, Santiago AG, Yang F. Single-molecule dynamics and mechanisms of metalloregulators and metallochaperones. Biochemistry 2013; 52:7170-83. [PMID: 24053279 DOI: 10.1021/bi400597v] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Understanding how cells regulate and transport metal ions is an important goal in the field of bioinorganic chemistry, a frontier research area that resides at the interface of chemistry and biology. This Current Topic reviews recent advances from the authors' group in using single-molecule fluorescence imaging techniques to identify the mechanisms of metal homeostatic proteins, including metalloregulators and metallochaperones. It emphasizes the novel mechanistic insights into how dynamic protein-DNA and protein-protein interactions offer efficient pathways via which MerR-family metalloregulators and copper chaperones can fulfill their functions. This work also summarizes other related single-molecule studies of bioinorganic systems and provides an outlook toward single-molecule imaging of metalloprotein functions in living cells.
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Affiliation(s)
- Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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5
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Christensen AL, Lohr C, Christensen SM, Stamou D. Single vesicle biochips for ultra-miniaturized nanoscale fluidics and single molecule bioscience. LAB ON A CHIP 2013; 13:3613-3625. [PMID: 23856986 DOI: 10.1039/c3lc50492a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
One of the major bottlenecks in the development of biochips is maintaining the structure and function of biomolecules when interfacing them with hard matter (glass, plastics, metals, etc.), a challenge that is exacerbated during miniaturization that inevitably increases the interface to volume ratio of these devices. Biochips based on immobilized vesicles circumvent this problem by encapsulating biomolecules in the protective environment of a lipid bilayer, thus minimizing interactions with hard surfaces. Here we review the development of biochips based on arrays of single nanoscale vesicles, their fabrication via controlled self-assembly, and their characterization using fluorescence microscopy. We also highlight their applications in selected fields such as nanofluidics and single molecule bioscience. Despite their great potential for improved biocompatibility, extreme miniaturization and high throughput, single vesicle biochips are still a niche technology that has yet to establish its commercial relevance.
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Affiliation(s)
- Andreas L Christensen
- Bionanotechnology and Nanomedicine Laboratory, Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark
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6
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Cell signaling experiments driven by optical manipulation. Int J Mol Sci 2013; 14:8963-84. [PMID: 23698758 PMCID: PMC3676767 DOI: 10.3390/ijms14058963] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 04/08/2013] [Accepted: 04/14/2013] [Indexed: 01/09/2023] Open
Abstract
Cell signaling involves complex transduction mechanisms in which information released by nearby cells or extracellular cues are transmitted to the cell, regulating fundamental cellular activities. Understanding such mechanisms requires cell stimulation with precise control of low numbers of active molecules at high spatial and temporal resolution under physiological conditions. Optical manipulation techniques, such as optical tweezing, mechanical stress probing or nano-ablation, allow handling of probes and sub-cellular elements with nanometric and millisecond resolution. PicoNewton forces, such as those involved in cell motility or intracellular activity, can be measured with femtoNewton sensitivity while controlling the biochemical environment. Recent technical achievements in optical manipulation have new potentials, such as exploring the actions of individual molecules within living cells. Here, we review the progress in optical manipulation techniques for single-cell experiments, with a focus on force probing, cell mechanical stimulation and the local delivery of active molecules using optically manipulated micro-vectors and laser dissection.
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7
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Schaefer JJ, Ma C, Harris JM. Confocal Raman microscopy probing of temperature-controlled release from individual, optically-trapped phospholipid vesicles. Anal Chem 2012; 84:9505-12. [PMID: 23043532 DOI: 10.1021/ac302346n] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Control of permeability of phospholipid vesicle (liposome) membranes is critical to their applications in analytical sensing, in fundamental studies of chemistry in small volumes, and in encapsulation and release of payloads for site-directed drug delivery. Applications of liposome formulations in drug delivery often take advantage of the enhanced permeability of phospholipid membranes at their gel-to-fluid phase transition, where the release of encapsulated molecules can be initiated by an increase in temperature. Despite numerous successful liposome formulations for encapsulation and release methods to study the kinetics, this process has been limited to investigations of bulk vesicle dispersions, which provide little or no information about the vesicle membrane structure and its relationship to the kinetics of trans-membrane transport. In this work, confocal Raman microscopy is adapted to study temperature-dependent release of a model compound, 3-nitrobenzene sulfonate (3-NBS), from individual optically trapped phospholipid vesicles, while simultaneously monitoring structural changes in the vesicle membrane reported by vibrational modes of phospholipid acyl chains and the local environment of the encapsulated compound. The confocal geometry allows efficient excitation and collection of Raman scattering from a single vesicle, while optical trapping allows more than hour-long observations of the same vesicle. With window factor analysis to resolve component spectra, temperature-controlled release of 3-NBS through vesicle membranes composed of pure 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was measured and compared to transport through a lysolipid-containing membrane specifically formulated for efficient drug delivery.
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Affiliation(s)
- Jonathan J Schaefer
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
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8
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Pinato G, Cojoc D, Lien LT, Ansuini A, Ban J, D'Este E, Torre V. Less than 5 Netrin-1 molecules initiate attraction but 200 Sema3A molecules are necessary for repulsion. Sci Rep 2012; 2:675. [PMID: 22997549 PMCID: PMC3447186 DOI: 10.1038/srep00675] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 09/03/2012] [Indexed: 11/09/2022] Open
Abstract
Guidance molecules, such as Sema3A or Netrin-1, induce growth cone (GC) repulsion or attraction. In order to determine the speed of action and efficiency of these guidance cues we developed an experimental procedure to deliver controlled amounts of these molecules. Lipid vesicles encapsulating 10-10(4) molecules of Sema3A or Netrin-1 were manipulated with high spatial and temporal resolution by optical tweezers and their photolysis triggered by laser pulses. Guidance molecules released from the vesicles diffused and reached the GC membrane in a few seconds. Following their arrival, GCs retracted or grew in 20-120 s. By determining the number of guidance molecules trapped inside vesicles and estimating the fraction of guidance molecules reaching the GC, we show that the arrival of less than 5 Netrin-1 molecules on the GC membrane is sufficient to induce growth. In contrast, the arrival of about 200 Sema3A molecules is necessary to induce filopodia repulsion.
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Affiliation(s)
- Giulietta Pinato
- Istituto Officina dei Materiali (IOM-CNR), Area Science Park, Trieste, Italy.
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9
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Keller AM, Benítez JJ, Klarin D, Zhong L, Goldfogel M, Yang F, Chen TY, Chen P. Dynamic multibody protein interactions suggest versatile pathways for copper trafficking. J Am Chem Soc 2012; 134:8934-43. [PMID: 22578168 DOI: 10.1021/ja3018835] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As part of intracellular copper trafficking pathways, the human copper chaperone Hah1 delivers Cu(+) to the Wilson's Disease Protein (WDP) via weak and dynamic protein-protein interactions. WDP contains six homologous metal binding domains (MBDs) connected by flexible linkers, and these MBDs all can receive Cu(+) from Hah1. The functional roles of the MBD multiplicity in Cu(+) trafficking are not well understood. Building on our previous study of the dynamic interactions between Hah1 and the isolated fourth MBD of WDP, here we study how Hah1 interacts with MBD34, a double-domain WDP construct, using single-molecule fluorescence resonance energy transfer (smFRET) combined with vesicle trapping. By alternating the positions of the smFRET donor and acceptor, we systematically probed Hah1-MBD3, Hah1-MBD4, and MBD3-MBD4 interaction dynamics within the multidomain system. We found that the two interconverting interaction geometries were conserved in both intermolecular Hah1-MBD and intramolecular MBD-MBD interactions. The Hah1-MBD interactions within MBD34 are stabilized by an order of magnitude relative to the isolated single-MBDs, and thermodynamic and kinetic evidence suggest that Hah1 can interact with both MBDs simultaneously. The enhanced interaction stability of Hah1 with the multi-MBD system, the dynamic intramolecular MBD-MBD interactions, and the ability of Hah1 to interact with multiple MBDs simultaneously suggest an efficient and versatile mechanism for the Hah1-to-WDP pathway to transport Cu(+).
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Affiliation(s)
- Aaron M Keller
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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10
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Heider EC, Myers GA, Harris JM. Spectroscopic microscopy analysis of the interior pH of individual phospholipid vesicles. Anal Chem 2011; 83:8230-8. [PMID: 21962221 DOI: 10.1021/ac2019987] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of phospholipid vesicles as reaction containers, as vehicles for pharmaceutical drug delivery, and as model systems for cells has prompted the development of new methods for analyzing the structure of vesicles and their contents. The pH of the interior of vesicles is of particular interest when analytes are encapsulated and concentrated with the use of a pH gradient. While the interior pH is generally measured for large populations of vesicles, we report the measurement of the interior pH of individual vesicles as their buffer contents are titrated by transfer of N-methylbutylamine (NMBA) into the vesicle by a pH gradient. The initially acidic buffer within the vesicles is titrated along with a small concentration of an encapsulated pH sensitive dye, 5,6-carboxy SNARF-1-dextran. Images of the indicator fluorescence from each vesicle and its dispersed fluorescence spectrum are recorded using epi-illumination spectral fluorescence microscopy. From a fit of the spectra to the respective acid and base forms of the fluorescent indicator, the interior pH of individual vesicles as a function of the concentration of the NMBA titrant in the external solution could be determined.
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Affiliation(s)
- Emily C Heider
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
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11
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Heider EC, Peterson EM, Barhoum M, Gericke KH, Harris JM. Quantitative fluorescence microscopy to determine molecular occupancy of phospholipid vesicles. Anal Chem 2011; 83:5128-36. [PMID: 21648957 DOI: 10.1021/ac200129n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Encapsulation of molecules in phospholipid vesicles provides unique opportunities to study chemical reactions in small volumes as well as the behavior of individual proteins, enzymes, and ribozymes in a confined region without requiring a tether to immobilize the molecule to a surface. These experiments generally depend on generating a predictable loading of vesicles with small numbers of target molecules and thus raise a significant measurement challenge, namely, to quantify molecular occupancy of vesicles at the single-molecule level. In this work, we describe an imaging experiment to measure the time-dependent fluorescence from individual dye molecules encapsulated in ~130 nm vesicles that are adhered to a glass surface. For determining a fit of the molecular occupancy data to a Poisson model, it is critical to count empty vesicles in the population since these dominate the sample when the mean occupancy is small, λ ≤ ~1. Counting empty vesicles was accomplished by subsequently labeling all the vesicles with a lipophilic dye and reimaging the sample. By counting both the empty vesicles and those containing fluors, and quantifying the number of fluors present, we demonstrate a self-consistent Poisson distribution of molecular occupancy for well-solvated molecules, as well as anomalies due to aggregation of dye, which can arise even at very low solution concentrations. By observation of many vesicles in parallel in an image, this approach provides quantitative information about the distribution of molecular occupancy in a population of vesicles.
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Affiliation(s)
- Emily C Heider
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA
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12
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Benítez JJ, Keller AM, Huffman DL, Yatsunyk LA, Rosenzweig AC, Chen P. Relating dynamic protein interactions of metallochaperones with metal transfer at the single-molecule level. Faraday Discuss 2011; 148:71-82; discussion 97-108. [PMID: 21322478 DOI: 10.1039/c004913a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Metallochaperones undertake specific interactions with their target proteins to deliver metal ions inside cells. Understanding how these protein interactions are coupled with the underlying metal transfer process is important, but challenging because they are weak and dynamic. Here we use a nanovesicle trapping scheme to enable single-molecule FRET measurements of the weak, dynamic interactions between the copper chaperone Hahl and the fourth metal binding domain (MBD4) of WDP. By monitoring the behaviors of single interacting pairs, we visualize their interactions in real time in both the absence and the presence of various equivalents of Cu(1+). Regardless of the proteins' metallation state, we observe multiple, interconverting interaction complexes between Hah1 and MBD4. Within our experimental limit, the overall interaction geometries of these complexes appear invariable, but their stabilities are dependent on the proteins' metallation state. In apo-holo Hah1-MBD4 interactions, the complexes are stabilized relative to that observed in the apo-apo interactions. This stabilization is indiscernible when Hah1's Cu(1+)-binding is eliminated or when both proteins have Cu(1+) loaded. The nature of this Cu(1+)-induced complex stabilization and of the interaction complexes are discussed. These Cu(1+)-induced effects on the Hah1-MBD4 interactions provide a step toward understanding how the dynamic protein interactions of copper chaperones are coupled with their metal transfer function.
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Affiliation(s)
- Jaime J Benítez
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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13
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Issadore D, Franke T, Brown KA, Westervelt RM. A microfluidic microprocessor: controlling biomimetic containers and cells using hybrid integrated circuit/microfluidic chips. LAB ON A CHIP 2010; 10:2937-2943. [PMID: 20835430 DOI: 10.1039/c0lc00092b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present an integrated platform for performing biological and chemical experiments on a chip based on standard CMOS technology. We have developed a hybrid integrated circuit (IC)/microfluidic chip that can simultaneously control thousands of living cells and pL volumes of fluid, enabling a wide variety of chemical and biological tasks. Taking inspiration from cellular biology, phospholipid bilayer vesicles are used as robust picolitre containers for reagents on the chip. The hybrid chip can be programmed to trap, move, and porate individual living cells and vesicles and fuse and deform vesicles using electric fields. The IC spatially patterns electric fields in a microfluidic chamber using 128 × 256 (32,768) 11 × 11 μm(2) metal pixels, each of which can be individually driven with a radio frequency (RF) voltage. The chip's basic functions can be combined in series to perform complex biological and chemical tasks and can be performed in parallel on the chip's many pixels for high-throughput operations. The hybrid chip operates in two distinct modes, defined by the frequency of the RF voltage applied to the pixels: Voltages at MHz frequencies are used to trap, move, and deform objects using dielectrophoresis and voltages at frequencies below 1 kHz are used for electroporation and electrofusion. This work represents an important step towards miniaturizing the complex chemical and biological experiments used for diagnostics and research onto automated and inexpensive chips.
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Affiliation(s)
- David Issadore
- School of Engineering and Applied Science, Harvard University, 29 Oxford Street, Cambridge, MA, USA
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14
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Chen Q, Rausch KG, Schönherr H, Vancso GJ. α-Chymotrypsin-Catalyzed Reaction Confined in Block-Copolymer Vesicles. Chemphyschem 2010; 11:3534-40. [DOI: 10.1002/cphc.201000429] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Chen P, Andoy NM, Benítez JJ, Keller AM, Panda D, Gao F. Tackling metal regulation and transport at the single-molecule level. Nat Prod Rep 2010; 27:757-67. [PMID: 20442963 PMCID: PMC2992825 DOI: 10.1039/b906691h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To maintain normal metal metabolism, organisms utilize dynamic cooperation of many biomacromolecules for regulating metal ion concentrations and bioavailability. How these biomacromolecules work together to achieve their functions is largely unclear. For example, how do metalloregulators and DNA interact dynamically to control gene expression to maintain healthy cellular metal level? And how do metal transporters collaborate dynamically to deliver metal ions? Here we review recent advances in studying the dynamic interactions of macromolecular machineries for metal regulation and transport at the single-molecule level: (1) The development of engineered DNA Holliday junctions as single-molecule reporters for metalloregulator-DNA interactions, focusing onMerR-family regulators. And (2) The development of nanovesicle trapping coupled with single molecule fluorescence resonance energy transfer (smFRET) for studying weak, transient interactions between the copper chaperone Hah1 and the Wilson disease protein. We describe the methodologies,the information content of the single-molecule results, and the insights into the biological functions of the involved biomacromolecules for metal regulation and transport. We also discuss remaining challenges from our perspective.
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Affiliation(s)
- Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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16
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Benítez JJ, Keller AM, Chen P. Nanovesicle trapping for studying weak protein interactions by single-molecule FRET. Methods Enzymol 2010; 472:41-60. [PMID: 20580959 DOI: 10.1016/s0076-6879(10)72016-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Protein-protein interactions are fundamental biological processes. While strong protein interactions are amenable to many characterization techniques including crystallography, weak protein interactions are challenging to study because of their dynamic nature. Single-molecule fluorescence resonance energy transfer (smFRET) can monitor dynamic protein interactions in real time, but are generally limited to strong interacting pairs because of the low concentrations needed for single-molecule detection. Here, we describe a nanovesicle trapping approach to enable smFRET study of weak protein interactions at high effective concentrations. We describe the experimental procedures, summarize the application in studying the weak interactions between intracellular copper transporters, and detail the single-molecule kinetic analysis of bimolecular interactions involving three states. Both the experimental approach and the theoretical analysis are generally applicable to studying many other biological processes at the single-molecule level.
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Affiliation(s)
- Jaime J Benítez
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
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17
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Tang J, Jofre AM, Kishore RB, Reiner JE, Greene ME, Lowman GM, Denker JS, Willis CCC, Helmerson K, Goldner LS. Generation and mixing of subfemtoliter aqueous droplets on demand. Anal Chem 2009; 81:8041-7. [PMID: 19711965 DOI: 10.1021/ac9014319] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a novel method of generating monodisperse subfemtoliter aqueous droplets on demand by means of piezoelectric injection. Droplets with volumes down to 200 aL are generated by this technique. The droplets are injected into a low refractive index perfluorocarbon so that they can be optically trapped. We demonstrate the use of optical tweezers to manipulate and mix droplets. For example, using optical tweezers we bring two droplets, one containing a calcium sensitive dye and the other calcium chloride, into contact. The droplets coalesce with a resulting reaction time of about 1 ms. The monodispersity, manipulability, repeatability, small size, and fast mixing afforded by this system offer many opportunities for nanochemistry and observation of chemical reactions on a molecule-by-molecule basis.
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Affiliation(s)
- Jianyong Tang
- Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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18
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Affiliation(s)
- Shaoyong Yu
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 2K6, Canada, and Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, H3A 2B2, Canada
| | - Tony Azzam
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 2K6, Canada, and Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, H3A 2B2, Canada
| | - Isabelle Rouiller
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 2K6, Canada, and Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, H3A 2B2, Canada
| | - Adi Eisenberg
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 2K6, Canada, and Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, H3A 2B2, Canada
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19
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Vijayakrishna K, Mecerreyes D, Gnanou Y, Taton D. Polymeric Vesicles and Micelles Obtained by Self-Assembly of Ionic Liquid-Based Block Copolymers Triggered by Anion or Solvent Exchange. Macromolecules 2009. [DOI: 10.1021/ma900549k] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kari Vijayakrishna
- Laboratoire de Chimie des Polymères Organiques, Université Bordeaux 1, CNRS-ENSCPB, 16 Avenue Pey-Berland, 33607 Pessac Cedex, France
| | - David Mecerreyes
- New Materials Department, CIDETEC-Centre for Electrochemical Technologies, Parque Tecnológico de San Sebastián, Paseo Miramón 196, San Sebastian, E-20009, Spain
| | - Yves Gnanou
- Laboratoire de Chimie des Polymères Organiques, Université Bordeaux 1, CNRS-ENSCPB, 16 Avenue Pey-Berland, 33607 Pessac Cedex, France
| | - Daniel Taton
- Laboratoire de Chimie des Polymères Organiques, Université Bordeaux 1, CNRS-ENSCPB, 16 Avenue Pey-Berland, 33607 Pessac Cedex, France
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20
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Chen Q, Schönherr H, Vancso GJ. Block-copolymer vesicles as nanoreactors for enzymatic reactions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:1436-1445. [PMID: 19283796 DOI: 10.1002/smll.200801455] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The impact of the spatial confinement of polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer (BCP) vesicles on the reactivity of encapsulated bovine pancreas trypsin is studied. Enzymes, as well as small molecules, are encapsulated with loading efficiencies up to 30% in BCP vesicles with variable internal volumes between 0.014 aL (internal vesicle diameter, d(in) = 30 nm) and 8 aL (d(in) = 250 nm), obtained by manipulating the vesicle preparation conditions. The kinetics of the trypsin-catalyzed reaction of a fluorogenic substrate inside and outside the vesicles is quantitatively estimated using fluorescence spectroscopic analyses in conjunction with the use of NaNO(2) as selective quencher for non-encapsulated fluorophores. The values of the catalytic turnover number obtained for reactions in differently sized nanoscale reactors show a significant increase (up to approximately 5x) with decreasing BCP vesicle volume, while the values of the Michaelis-Menten constant decrease. The observed increase in enzyme efficiency by two orders of magnitude compared to bulk solution is attributed to an enhanced rate of enzyme-substrate and molecule-wall collisions inside the nanosized reactors, as predicted in the literature on the basis of Monte Carlo simulations.
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Affiliation(s)
- Qi Chen
- Department of Materials Science and Technology of Polymers University of Twente, MESA+ Institute for Nanotechnology Postbus 217, 7500 AE Enschede, The Netherlands
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21
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Liu Y, Jung SY, Collier CP. Shear-Driven Redistribution of Surfactant Affects Enzyme Activity in Well-Mixed Femtoliter Droplets. Anal Chem 2009; 81:4922-8. [DOI: 10.1021/ac900624h] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yu Liu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, P.O. Box 2008, MS-6493, Oak Ridge, Tennessee 37831
| | - Seung-Yong Jung
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, P.O. Box 2008, MS-6493, Oak Ridge, Tennessee 37831
| | - C. Patrick Collier
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, P.O. Box 2008, MS-6493, Oak Ridge, Tennessee 37831
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22
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Rosenkranz T, Katranidis A, Atta D, Gregor I, Enderlein J, Grzelakowski M, Rigler P, Meier W, Fitter J. Observing Proteins as Single Molecules Encapsulated in Surface-Tethered Polymeric Nanocontainers. Chembiochem 2009; 10:702-9. [DOI: 10.1002/cbic.200800739] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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24
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Bolinger PY, Stamou D, Vogel H. An Integrated Self-Assembled Nanofluidic System for Controlled Biological Chemistries. Angew Chem Int Ed Engl 2008; 47:5544-9. [DOI: 10.1002/anie.200801606] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Pierre-Yves Bolinger
- Institut des Sciences et Ingénierie Chimiques; Ecole Polytechnique Fédérale de Lausanne; 1015 Lausanne Switzerland
- Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology & Nano-Science Centre; University of Copenhagen; Universitetsparken 5 2100 Copenhagen Denmark
| | - Dimitrios Stamou
- Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology & Nano-Science Centre; University of Copenhagen; Universitetsparken 5 2100 Copenhagen Denmark
| | - Horst Vogel
- Institut des Sciences et Ingénierie Chimiques; Ecole Polytechnique Fédérale de Lausanne; 1015 Lausanne Switzerland
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25
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Bolinger PY, Stamou D, Vogel H. An Integrated Self-Assembled Nanofluidic System for Controlled Biological Chemistries. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801606] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Pierre-Yves Bolinger
- Institut des Sciences et Ingénierie Chimiques; Ecole Polytechnique Fédérale de Lausanne; 1015 Lausanne Switzerland
- Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology & Nano-Science Centre; University of Copenhagen; Universitetsparken 5 2100 Copenhagen Denmark
| | - Dimitrios Stamou
- Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology & Nano-Science Centre; University of Copenhagen; Universitetsparken 5 2100 Copenhagen Denmark
| | - Horst Vogel
- Institut des Sciences et Ingénierie Chimiques; Ecole Polytechnique Fédérale de Lausanne; 1015 Lausanne Switzerland
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26
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Callari FL, Petralia S, Conoci S, Sortino S. Light-triggered DNA release by dynamic monolayer films. NEW J CHEM 2008. [DOI: 10.1039/b808118b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Affiliation(s)
- Tse-Ming Hsin
- Ames Laboratory-USDOE and Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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28
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29
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Liu X, Zhao R, Zhang Y, Jiang X, Yue J, Jiang P, Zhang Z. Using giant unilamellar lipid vesicle micro-patterns as ultrasmall reaction containers to observe reversible ATP synthesis/hydrolysis of F0F1-ATPase directly. Biochim Biophys Acta Gen Subj 2007; 1770:1620-6. [PMID: 17913367 DOI: 10.1016/j.bbagen.2007.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 08/01/2007] [Accepted: 08/01/2007] [Indexed: 10/22/2022]
Abstract
F(0)F(1)-ATPase within chromatophores, which was labeled with pH-sensitive quantum dots, was encapsulated in large unilamellar lipid vesicles (LUVs) through reverse-phase evaporation. Then a microarray of chromatophore-containing LUVs was created using a micro-contact printing (mu-CP) technique. Through controlled dehydration-rehydration of the lipid patterns, a microarray of single chromatophore-containing giant unilamellar lipid vesicles (GUVs) was formed with desired size and uniform shape. The reversible ATP synthesis/hydrolysis of F(0)F(1)-ATPase in GUVs was directly observed by fluorescence microscopy through the fluorescence intensity increase/decrease in the pH-sensitive quantum dots labeled on the outer surface of the chromatophore. To the best of our knowledge, this is the first direct observation of the reversible behavior of F(0)F(1)-ATPase at the bulk scale.
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Affiliation(s)
- Xiaolong Liu
- The Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
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30
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Lee ES, Robinson D, Rognlien JL, Harnett CK, Simmons BA, Bowe Ellis CR, Davalos RV. Microfluidic electroporation of robust 10-μm vesicles for manipulation of picoliter volumes. Bioelectrochemistry 2006; 69:117-25. [PMID: 16483852 DOI: 10.1016/j.bioelechem.2005.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 12/01/2005] [Accepted: 12/12/2005] [Indexed: 11/30/2022]
Abstract
We present a new way to transport and handle picoliter volumes of analytes in a microfluidic context through electrically monitored electroporation of 10-25 microm vesicles. In this method, giant vesicles are used to isolate analytes in a microfluidic environment. Once encapsulated inside a vesicle, contents will not diffuse and become diluted when exposed to pressure-driven flow. Two vesicle compositions have been developed that are robust enough to withstand electrical and mechanical manipulation in a microfluidic context. These vesicles can be guided and trapped, with controllable transfer of material into or out of their confined environment. Through electroporation, vesicles can serve as containers that can be opened when mixing and diffusion are desired, and closed during transport and analysis. Both vesicle compositions contain lecithin, an ethoxylated phospholipid, and a polyelectrolyte. Their performance is compared using a prototype microfluidic device and a simple circuit model. It was observed that the energy density threshold required to induce breakdown was statistically equivalent between compositions, 10.2+/-5.0 mJ/m2 for the first composition and 10.5+/-1.8 mJ/m2 for the second. This work demonstrates the feasibility of using giant, robust vesicles with microfluidic electroporation technology to manipulate picoliter volumes on-chip.
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Affiliation(s)
- Eunice S Lee
- Sandia National Laboratories, P.O. Box 969, Livermore, CA 94551, USA
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31
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Chécot F, Rodríguez-Hernández J, Gnanou Y, Lecommandoux S. pH-responsive micelles and vesicles nanocapsules based on polypeptide diblock copolymers. ACTA ACUST UNITED AC 2006; 24:81-5. [PMID: 16870504 DOI: 10.1016/j.bioeng.2006.05.015] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The self-assembly of well-defined polypeptide-based diblock copolymers into micelles and vesicles is presented. The stimuli-responsive behavior of polypeptides to pH and ionic strength is used to produce stimuli-responsive nanoparticles with controlled size and shape. Results focusing on micelles and vesicles obtained from polypeptide-based diblock copolymers that are particularly promising for biomedical applications are detailed by means of static and dynamic light scattering analysis, UV circular dichroism, NMR and small angle neutron scattering experiments. Also systems able to form vesicles with a narrow size distribution at basic and acid pH going through a single molecule intermediate state are presented. These nanoparticles are particularly interesting for encapsulation and delivery purpose at a controlled pH.
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Affiliation(s)
- F Chécot
- Laboratoire de Chimie des Polymères Organiques (LCPO-UMR5629), CNRS, ENSCPB, University Bordeaux 1, 16 Avenue Pey Berland, 33607 Pessac-Cedex, France
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32
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Dittrich PS, Heule M, Renaud P, Manz A. On-chip extrusion of lipid vesicles and tubes through microsized apertures. LAB ON A CHIP 2006; 6:488-93. [PMID: 16572210 DOI: 10.1039/b517670k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In this work we present the formation of micrometre-sized lipid vesicles and tubes with perfectly homogeneous diameter and extraordinary length. The method is a novel approach for unconventional fabrication of soft-matter microstructured devices based on the combination of top-down and bottom-up fabrication processes. Photolithography techniques are applied to fabricate microsized apertures that provide the requirements to form lipid structures with predictable size and to align and guide the vesicles and tubes in microstructured channels. The formation is facilitated by self-assembly of polar lipids to a lipid membrane that is afterwards forced to undergo a shape transformation by extrusion through a microsized aperture. Both the geometrical restriction by the small aperture and the pressure difference between the top and bottom sides of the aperture determine the form and length of the vesicles and tubes. A strong pressure difference favors the formation of lipid tubes, while a low pressure difference results in the formation of vesicle bunches with spherical and cylindrical shapes. Potential applications for the formed lipid structures could be as microreactors and transport channels as well as in the construction of flexible microfluidic networks.
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Affiliation(s)
- Petra S Dittrich
- ISAS - Institute for Analytical Sciences, Bunsen-Kirchhoff-Str. 11, D-44139 Dortmund, Germany.
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33
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Kuyper CL, Kuo JS, Mutch SA, Chiu DT. Proton Permeation into Single Vesicles Occurs via a Sequential Two-Step Mechanism and Is Heterogeneous. J Am Chem Soc 2006; 128:3233-40. [PMID: 16522104 DOI: 10.1021/ja057349c] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article describes the first single-vesicle study of proton permeability across the lipid membrane of small (approximately 100 nm) uni- and multilamellar vesicles, which were composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). To follow proton permeation into the internal volume of each vesicle, we encapsulated carboxyfluorescein, a pH-sensitive dye whose fluorescence was quenched in the presence of excess protons. A microfluidic platform was used for easy exchange of high- and low-pH solutions, and fluorescence quenching of single vesicles was detected with single-molecule total internal reflection fluorescence (TIRF) microscopy. Upon solution exchange and acidification of the extravesicular solution (from pH 9 to 3.5), we observed for each vesicle a biphasic decay in fluorescence. Through single-vesicle analysis, we found that rate constants for the first decay followed a Poisson distribution, whereas rate constants for the second decay followed a normal distribution. We propose that proton permeation into each vesicle first arose from formation of transient pores and then transitioned into the second decay phase, which occurred by the solubility-diffusion mechanism. Furthermore, for the bulk population of vesicles, the decay rate constant and vesicle intensity (dependent on size) correlated to give an average permeability coefficient; however, for individual vesicles, we found little correlation, which suggested that proton permeability among single vesicles was heterogeneous in our experiments.
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Affiliation(s)
- Christopher L Kuyper
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
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34
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Zhang H, Du J, Zhao J, Li YZ. Evaluation of fusion between liposomes and erythrocytes for intracellular derivatization of amino acids in cells. J Chromatogr A 2006; 1110:81-5. [PMID: 16460741 DOI: 10.1016/j.chroma.2006.01.082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 01/02/2006] [Accepted: 01/18/2006] [Indexed: 11/22/2022]
Abstract
Erythrocytes were fused with liposome for intracellular derivatization of amino acids in cells. The fusion efficiency was evaluated with capillary electrophoresis (CE) and laser-induced fluorescence (LIF) detection. Reagent fluorescein isothiocyanate (FITC) was enveloped in liposomes and introduced into erythrocytes by fusion between liposomes and erythrocytes. The amino acids in the fused cells were derivated by the introduced FITC and the derivated amino acids were extracted for detection by capillary electrophoresis equipped with laser-induced fluorescence detector. The fusion conditions were investigated. It was found that incubation of liposome and erythrocytes in the presence of 13% polyethylene glycol 6000 (PEG 6000) for 15min produced the highest fusion efficiency and kept the erythrocytes stability.
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Affiliation(s)
- Hua Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
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35
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Zhang JX, Qiu LY, Jin Y, Zhu KJ. Multimorphological Self-Assemblies of Amphiphilic Graft Polyphosphazenes with Oligopoly(N-isopropylacrylamide) and Ethyl 4-Aminobenzoate as Side Groups. Macromolecules 2006. [DOI: 10.1021/ma052152q] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jian Xiang Zhang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China, and Institute of Polymer Science, Zhejiang University, Hangzhou 310027, China
| | - Li Yan Qiu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China, and Institute of Polymer Science, Zhejiang University, Hangzhou 310027, China
| | - Yi Jin
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China, and Institute of Polymer Science, Zhejiang University, Hangzhou 310027, China
| | - Kang Jie Zhu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China, and Institute of Polymer Science, Zhejiang University, Hangzhou 310027, China
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36
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37
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Zhang JX, Qiu LY, Zhu KJ. Solvent Controlled Multi-Morphological Self-Assembly of Amphiphilic Graft Copolymers. Macromol Rapid Commun 2005. [DOI: 10.1002/marc.200500467] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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38
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Dittrich PS, Manz A. Single-molecule fluorescence detection in microfluidic channels—the Holy Grail in μTAS? Anal Bioanal Chem 2005; 382:1771-82. [PMID: 16075229 DOI: 10.1007/s00216-005-3335-9] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 05/12/2005] [Accepted: 05/19/2005] [Indexed: 10/25/2022]
Abstract
Both single-molecule detection (SMD) methods and miniaturization technologies have developed very rapidly over the last ten years. By merging these two techniques, it may be possible to achieve the optimal requirements for the analysis and manipulation of samples on a single molecule scale. While miniaturized structures and channels provide the interface required to handle small particles and molecules, SMD permits the discovery, localization, counting and identification of compounds. Widespread applications, across various bioscience/analytical science fields, such as DNA-analysis, cytometry and drug screening, are envisaged. In this review, the unique benefits of single fluorescent molecule detection in microfluidic channels are presented. Recent and possible future applications are discussed.
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Affiliation(s)
- Petra S Dittrich
- Department of Miniaturization, Institute for Analytical Sciences (ISAS), Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany.
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39
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Konkoli Z, Karlsson A, Orwar O. The Pair Approach Applied to Kinetics in Restricted Geometries: Strengths and Weaknesses of the Method. J Phys Chem B 2003. [DOI: 10.1021/jp034667u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Z. Konkoli
- Department of Applied Physics, Chalmers University of Technology and Göteborg University, SE-412 96 Göteborg, Sweden, Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden, Department of Physical Chemistry and Microtechnology Centre at Chalmers, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - A. Karlsson
- Department of Applied Physics, Chalmers University of Technology and Göteborg University, SE-412 96 Göteborg, Sweden, Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden, Department of Physical Chemistry and Microtechnology Centre at Chalmers, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - O. Orwar
- Department of Applied Physics, Chalmers University of Technology and Göteborg University, SE-412 96 Göteborg, Sweden, Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden, Department of Physical Chemistry and Microtechnology Centre at Chalmers, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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40
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Lerch HP, Mikhailov AS, Hess B. Conformational-relaxation models of single-enzyme kinetics. Proc Natl Acad Sci U S A 2002; 99:15410-5. [PMID: 12429859 PMCID: PMC137730 DOI: 10.1073/pnas.232376799] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2002] [Indexed: 11/18/2022] Open
Abstract
Fluorescent spectroscopy experiments with single-enzyme molecules yield a large volume of statistical data that can be analyzed and interpreted using stochastic models of enzyme action. Here, we present two models, each based on the mechanism that an enzyme molecule must pass through a sequence of conformational transformations to complete its catalytic turnover cycle. In the simplest model, only one path leading to the release of product is present. In contrast to this, two different catalytic paths are possible in the second considered model. If a cycle is started from an active state, immediately after the previous product release, it follows a different conformational route and is much shorter. Our numerical investigations show that both models generate non-Markovian molecular statistics. However, their memory landscapes and distributions of cycle times are significantly different. The memory landscape of the double-path model bears strong similarity to the recent experimental data for horseradish peroxidase.
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Affiliation(s)
- Hans-Philipp Lerch
- Abteilung Physikalische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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41
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Karlsson M, Sott K, Davidson M, Cans AS, Linderholm P, Chiu D, Orwar O. Formation of geometrically complex lipid nanotube-vesicle networks of higher-order topologies. Proc Natl Acad Sci U S A 2002; 99:11573-8. [PMID: 12185244 PMCID: PMC129310 DOI: 10.1073/pnas.172183699] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a microelectrofusion method for construction of fluid-state lipid bilayer networks of high geometrical complexity up to fully connected networks with genus = 3 topology. Within networks, self-organizing branching nanotube architectures could be produced where intersections spontaneously arrange themselves into three-way junctions with an angle of 120 degrees between each nanotube. Formation of branching nanotube networks appears to follow a minimum-bending energy algorithm that solves for pathway minimization. It is also demonstrated that materials can be injected into specific containers within a network by nanotube-mediated transport of satellite vesicles having defined contents. Using a combination of microelectrofusion, spontaneous nanotube pattern formation, and satellite-vesicle injection, complex networks of containers and nanotubes can be produced for a range of applications in, for example, nanofluidics and artificial cell design. In addition, this electrofusion method allows integration of biological cells into lipid nanotube-vesicle networks.
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Affiliation(s)
- Mattias Karlsson
- Department of Physical Chemistry and Microtechnology Center, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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42
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Shin I, Wachtel E, Roth E, Bon C, Silman I, Weiner L. Thermal denaturation of Bungarus fasciatus acetylcholinesterase: Is aggregation a driving force in protein unfolding? Protein Sci 2002; 11:2022-32. [PMID: 12142456 PMCID: PMC2373691 DOI: 10.1110/ps.0205102] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A monomeric form of acetylcholinesterase from the venom of Bungarus fasciatus is converted to a partially unfolded molten globule species by thermal inactivation, and subsequently aggregates rapidly. To separate the kinetics of unfolding from those of aggregation, single molecules of the monomeric enzyme were encapsulated in reverse micelles of Brij 30 in 2,2,4-trimethylpentane, or in large unilamellar vesicles of egg lecithin/cholesterol at various protein/micelle (vesicle) ratios. The first-order rate constant for thermal inactivation at 45 degrees C, of single molecules entrapped within the reverse micelles (0.031 min(-1)), was higher than in aqueous solution (0.007 min(-1)) or in the presence of normal micelles (0.020 min(-1)). This clearly shows that aggregation does not provide the driving force for thermal inactivation of BfAChE. Within the large unilamellar vesicles, at average protein/vesicle ratios of 1:1 and 10:1, the first-order rate constants for thermal inactivation of the encapsulated monomeric acetylcholinesterase, at 53 degrees C, were 0.317 and 0.342 min(-1), respectively. A crosslinking technique, utilizing the photosensitive probe, hypericin, showed that thermal denaturation produces a distribution of species ranging from dimers through to large aggregates. Consequently, at a protein/vesicle ratio of 10:1, aggregation can occur upon thermal denaturation. Thus, these experiments also demonstrate that aggregation does not drive the thermal unfolding of Bungarus fasciatus acetylcholinesterase. Our experimental approach also permitted monitoring of recovery of enzymic activity after thermal denaturation in the absence of a competing aggregation process. Whereas no detectable recovery of enzymic activity could be observed in aqueous solution, up to 23% activity could be obtained for enzyme sequestered in the reverse micelles.
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Affiliation(s)
- I Shin
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
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43
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Lerch HP, Stange P, Mikhailov AS, Hess B. Mutual Synchronization of Molecular Turnover Cycles in Allosteric Enzymes III. Intramolecular Cooperativity. J Phys Chem B 2002. [DOI: 10.1021/jp0136314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hans-Philipp Lerch
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany, and Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany
| | - Pedro Stange
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany, and Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany
| | - Alexander S. Mikhailov
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany, and Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany
| | - Benno Hess
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany, and Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany
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44
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Abstract
Self-assembly of reactive amphiphilic block copolymers is used to prepare nanostructured hydrogels with exceptional permeability properties, vesicular structures and planar, freestanding membranes in aqueous solution. Although the underlying block copolymer membranes are two-three-fold thicker than conventional lipid bilayers, they can be regarded as mimetic of biological membranes and can be used as a matrix for membrane-spanning proteins. Surprisingly, the proteins remain functional, despite the extreme thickness of the membranes and even after polymerization of the reactive block copolymers. The unique combination of block copolymers with membrane proteins allows the preparation of mechanically stable, defect-free membranes and nanocapsules that have highly selective permeability and/or specific recognition sites. This is documented by some representative examples.
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Affiliation(s)
- Corinne Nardin
- Institut für Physikalische Chemie, Universität Basel, Switzerland
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45
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Boukobza E, Sonnenfeld A, Haran G. Immobilization in Surface-Tethered Lipid Vesicles as a New Tool for Single Biomolecule Spectroscopy. J Phys Chem B 2001. [DOI: 10.1021/jp012016x] [Citation(s) in RCA: 246] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Erez Boukobza
- Chemical Physics Department, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alan Sonnenfeld
- Chemical Physics Department, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gilad Haran
- Chemical Physics Department, Weizmann Institute of Science, Rehovot 76100, Israel
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