651
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Puu G, Artursson E, Gustafson I, Lundström M, Jass J. Distribution and stability of membrane proteins in lipid membranes on solid supports. Biosens Bioelectron 2000; 15:31-41. [PMID: 10826641 DOI: 10.1016/s0956-5663(00)00050-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacteriorhodopsin and the nicotinic acetylcholine receptor were biotinylated and reconstituted in lipidic membranes on silicon supports by fusion with proteoliposomes. The presence and distribution of the proteins were studied by binding with streptavidin. Radio-labelled streptavidin was employed for quantifying the amounts of protein remaining in the supported membranes after storage in buffer. The proteins within the membranes remained bound to the surface for weeks. The biological activity of reconstituted unlabelled receptor upon storage showed stability in membranes formed on silicon supports and a reduced stability when formed onto lipid monolayer covered supports. Atomic force microscopy studies on preparations in liquid showed bilayer structures but also attached, partly fused liposomes and membrane particles. In air, the surface was smoother and contained less of liposomes and more of stacked lipid layers. Preparations labelled with streptavidin conjugated to colloidal gold and imaged in air showed the proteins individually distributed, with no protein-rich patches or protein aggregates.
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Affiliation(s)
- G Puu
- Defence Research Establishment, Umeå, Sweden.
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652
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Multilayered assembly of dendrimers with enzymes on gold: thickness-controlled biosensing interface. Anal Chem 2000; 72:922-6. [PMID: 10739193 DOI: 10.1021/ac991299a] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new approach to construct a multilayered enzyme film on the Au surface for use as a biosensing interface is described. The film was prepared by alternate layer-by-layer depositions of G4 poly(amidoamine) dendrimers and periodate-oxidized glucose oxidase (GOx). The cyclic voltammograms obtained from the Au electrodes modified with the GOx/dendrimer multilayers revealed that bioelectrocatalytic response is directly correlated to the number of deposited bilayers, that is, to the amount of active enzyme immobilized on the Au electrode surface. From the analysis of voltammetric signals, the coverage of active enzyme per GOx/dendrimer bilayer during the multilayer-forming steps was estimated, which demonstrates that the multilayer is constructed in a spatially ordered manner. Also, with the ellipsometric measurements, a linear increment of the film thickness was registered, supporting the formation of the proposed multilayered structure. The E5D5 electrode showed the sensitivity of 14.7 microA x mM(-1) glucose x cm(-2) and remained stable over 20 days under day-by-day calibrations. The proposed method is simple and would be applicable to the constructions of thickness- and sensitivity-controllable biosensing interfaces composed of multienzymes as well as a single enzyme.
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653
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Opitz N. 25th ANNIVERSARY OF FLUORESCENCE OPTICAL BIOSENSORS (OPTODES): PAST, PRESENCE AND FUTURE. BIOMED ENG-BIOMED TE 2000. [DOI: 10.1515/bmte.2000.45.s1.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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654
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Seitz M, Ter-Ovanesyan E, Hausch M, Park CK, Zasadzinski JA, Zentel R, Israelachvili JN. Formation of Tethered Supported Bilayers by Vesicle Fusion onto Lipopolymer Monolayers Promoted by Osmotic Stress. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2000; 16:6067-6070. [PMID: 20953315 PMCID: PMC2953954 DOI: 10.1021/la9915771] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Affiliation(s)
- Markus Seitz
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, and BUGH Wuppertal, Fachbereich Chemie und Institut für Materialwissenschaften, Gauss Strasse 20, D-42097 Wuppertal, Germany
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655
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Kelly D, Grace KM, Song X, Swanson BI, Frayer D, Mendes SB, Peyghambarian N. Integrated optical biosensor for detection of multivalent proteins. OPTICS LETTERS 1999; 24:1723-1725. [PMID: 18079915 DOI: 10.1364/ol.24.001723] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We have developed a simple, highly sensitive and specific optical waveguide sensor for the detection of multivalent proteins. The optical biosensor is based on optically tagged glycolipid receptors embedded within a fluid phospholipid bilayer membrane formed upon the surface of a planar optical waveguide. Binding of multivalent cholera toxin triggers a fluorescence resonance energy transfer that results in a two-color optical change that is monitored by measurement of emitted luminescence above the waveguide surface. The sensor approach is highly sensitive and specific and requires no additional reagents and washing steps. Demonstration of protein-receptor recognition by use of planar optical waveguides provides a path forward for the development of fieldable miniaturized biosensor arrays.
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656
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Abstract
In February 1997, researchers created Dolly, a lamb cloned from the DNA of an adult sheep. This was supposed to be impossible (or at least generations away), but suddenly it was here--a clone of a higher mammal. Whatever Dolly's ultimate significance, she conclusively demonstrated the growing power of biotechnology. Many have come to the conclusion that advances in biotechnology will fundamentally transform medicine during the coming decade. Society is in the midst of a technical revolution that will have the same relevance as the development of the printing press, the internal combustion engine, and the microprocessor. Computers have become the key tools in the accelerating progress that is occurring in the field of biotechnology. At the same time, genetic, evolutionary, and other biologic processes are providing new models for the development of computer hardware and software. Today represents the early stages of what has been called the "bionic convergence": the convergence of the biologic revolution with the information revolution, the joining of biology with electronics. Virtually everything that is important to health care practitioners and patients--diagnostic techniques, means of understanding disease causes, methods of treatment, approaches to prevention, health care facility design, medical education, and legal and ethical issues--will be changed by the revolutions currently underway in the fields of biotechnology and genetic medicine. The following monograph includes several forecasts about a range of possible opportunities that may have enormous effects on health care during the next century. These forecasts address the potential impacts of biotechnology on disease detection and diagnosis, treatment, prevention, nanotechnology, and other areas of medical significance. Every area of beneficiary care will be affected as the changes implied by these forecasts begin to develop. Beneficiary care will continue to see the emergence of a "forecast, prevent, and manage" paradigm. The emphasis will be on disease prevention, health promotion, and the creation of healthy communities. New diagnostic and treatment opportunities will be available as a consequence of breakthroughs in genetic medicine. The health care system will view health as a whole, as a person's overall sense of well-being--an entity that encompasses much more than the absence of symptoms.
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Affiliation(s)
- R Zajtchuk
- Center for Advanced Technology and International Health, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois, USA
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657
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Chen L, McBranch DW, Wang HL, Helgeson R, Wudl F, Whitten DG. Highly sensitive biological and chemical sensors based on reversible fluorescence quenching in a conjugated polymer. Proc Natl Acad Sci U S A 1999; 96:12287-92. [PMID: 10535914 PMCID: PMC22909 DOI: 10.1073/pnas.96.22.12287] [Citation(s) in RCA: 754] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The fluorescence of a polyanionic conjugated polymer can be quenched by extremely low concentrations of cationic electron acceptors in aqueous solutions. We report a greater than million-fold amplification of the sensitivity to fluorescence quenching compared with corresponding "molecular excited states." Using a combination of steady-state and ultrafast spectroscopy, we have established that the dramatic quenching results from weak complex formation [polymer(-)/quencher(+)], followed by ultrafast electron transfer from excitations on the entire polymer chain to the quencher, with a time constant of 650 fs. Because of the weak complex formation, the quenching can be selectively reversed by using a quencher-recognition diad. We have constructed such a diad and demonstrate that the fluorescence is fully recovered on binding between the recognition site and a specific analyte protein. In both solutions and thin films, this reversible fluorescence quenching provides the basis for a new class of highly sensitive biological and chemical sensors.
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Affiliation(s)
- L Chen
- Center for Material Science, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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658
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Nakaminami T, Ito S, Kuwabata S, Yoneyama H. A biomimetic phospholipid/alkanethiolate bilayer immobilizing uricase and an electron mediator on an Au electrode for amperometric determination of uric acid. Anal Chem 1999; 71:4278-83. [PMID: 10517148 DOI: 10.1021/ac981371p] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A biomimetic bilayer membrane immobilizing uricase (urate oxidase; EC 1.7.3.3) (UOx) and a redox agent of 1-methoxy-5-methylphenazinium (MMP) was fabricated on an Au electrode substrate with use of the Au substrate coated with a self-assembled monolayer of n-octanethiolate (OT/Au) and L-alpha-phosphatidylcholine beta-oleoyl-gamma-palmitoyl (PCOP). The preparation was carried out by successively immersing an Au electrode substrate in an ethanol solution of OT, an MMP aqueous solution, and a suspension of proteoliposome formed by PCOP containing UOx and MMP. The prepared electrode exhibited such fast steady amperometric responses to uric acid as to allow its determination within 20 s after injecting uric acid, indicating that UOx-catalyzed electrochemical oxidation of uric acid was accomplished with assistance of electron mediation by MMP between UOx and the Au substrate. An increase in the response currents with increasing concentration of uric acid was obtained in a concentration range of uric acid found in healthy human blood. Any interference in the current response that is caused by direct anodic oxidation of uric acid or ascorbic acid was not observed at the prepared sensor electrode because the densely packed bilayer effectively blocked the diffusion of these substrates toward the Au surface, making it possible to determine amperometrically uric acid at the electrode with high precision.
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Affiliation(s)
- T Nakaminami
- Department of Applied Chemistry, Faculty of Engineering, Osaka University, Japan
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659
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Naumann R, Schmidt E, Jonczyk A, Fendler K, Kadenbach B, Liebermann T, Offenhäusser A, Knoll W. The peptide-tethered lipid membrane as a biomimetic system to incorporate cytochrome c oxidase in a functionally active form. Biosens Bioelectron 1999. [DOI: 10.1016/s0956-5663(99)00036-6] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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660
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Wong JY, Park CK, Seitz M, Israelachvili J. Polymer-cushioned bilayers. II. An investigation of interaction forces and fusion using the surface forces apparatus. Biophys J 1999; 77:1458-68. [PMID: 10465756 PMCID: PMC1300433 DOI: 10.1016/s0006-3495(99)76993-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We have created phospholipid bilayers supported on soft polymer "cushions" which act as deformable substrates (see accompanying paper, Wong, J. Y., J. Majewski, M. Seitz, C. K. Park, J. N. Israelachvili, and G. S. Smith. 1999. Biophys. J. 77:1445-1457). In contrast to "solid-supported" membranes, such "soft-supported" membranes can exhibit more natural (higher) fluidity. Our bilayer system was constructed by adsorption of small unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles onto polyethylenimine (PEI)-supported Langmuir-Blodgett lipid monolayers on mica. We used the surface forces apparatus (SFA) to investigate the long-range forces, adhesion, and fusion of two DMPC bilayers both above and below their main transition temperature (T(m) approximately 24 degrees C). Above T(m), hemi-fusion activation pressures of apposing bilayers were considerably smaller than for solid-supported bilayers, e.g., directly supported on mica. After separation, the bilayers naturally re-formed after short healing times. Also, for the first time, complete fusion of two fluid (liquid crystalline) phospholipid bilayers was observed in the SFA. Below T(m) (gel state), very high pressures were needed for hemi-fusion and the healing process became very slow. The presence of the polymer cushion significantly alters the interaction potential, e.g., long-range forces as well as fusion pressures, when compared to solid-supported systems. These fluid model membranes should allow the future study of integral membrane proteins under more physiological conditions.
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Affiliation(s)
- J Y Wong
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106 USA
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661
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Mozsolits H, Lee TH, Wirth HJ, Perlmutter P, Aguilar MI. The interaction of bioactive peptides with an immobilized phosphatidylcholine monolayer. Biophys J 1999; 77:1428-44. [PMID: 10465754 PMCID: PMC1300431 DOI: 10.1016/s0006-3495(99)76991-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The interaction of three bioactive peptides, bombesin, beta-endorphin, and glucagon with a phosphatidylcholine monolayer that was immobilized to porous silica particles and packed into a stainless steel column cartridge, has been studied using dynamic elution techniques. This immobilized lipid monolayer provides a biophysical model system with which to study the binding of peptides to a lipid membrane. In particular, the influence of temperature and methanol concentration on the affinity of each peptide for the immobilized lipid surface was assessed. For all test peptides, nonlinear retention plots were observed at all temperatures that contrasted sharply with the simple linear plots observed for the small unstructured control molecules N-acetyltryptophanamide and diphenylalanine. An analysis of the thermodynamics of the interaction of peptides with the immobilized monolayer was also carried out. The results revealed that while the peptides interacted with the monolayer predominantly through hydrophobic interactions, the relative contribution of DeltaH(assoc)(O) and DeltaS(assoc)(O) to the overall free energy of association was dependent on the temperature and methanol concentration. In particular, it was evident that under most conditions, the binding of the peptides to the immobilized lipid monolayer was enthalpy-driven, i.e., mediated by nonclassical hydrophobic interactions. Significant band-broadening and asymmetric and split peaks were also observed for bombesin, beta-endorphin, and glucagon at different temperatures and methanol concentrations. These changes in affinity and peak shape are consistent with the formation of multiple conformational species during the interaction of these peptides with the lipid monolayer. In addition, the binding behavior of the three test peptides on an n-octylsilica surface that lacked the phospho headgroups of the phospholipid was significantly different from that observed with the immobilized phosphatidylcholine surface, indicating a specificity of interaction between the peptides and the lipid surface. Overall, these experimental results demonstrate that the biomimetic phosphatidylcholine monolayer provides a stable and sensitive system with which to explore the molecular mechanism of peptide conformational changes during membrane interactions.
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Affiliation(s)
- H Mozsolits
- Department of Biochemistry & Molecular Biology, Monash University, Victoria 3168, Australia
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662
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Abstract
A biosensor technology is described which provides a direct measurement for functional molecular interactions, at the surface of a tethered bilayer membrane, through the electrical transduction of chemically modified ion-channels. High sensitivity of analyte detection is achieved due to the large flux of ions transmitted through the ion channel. The biomimetic sensor surface allows the molecular recognition to be measured in complex biological matrices (such as blood and sera) without compromising sensitivity. We have used the sensor for activity and concentration measurements for a range of analytes, which include bacteria, DNA, proteins and drugs. We have a quantitative model for the biosensor performance which is described by three-dimensional molecular interactions with the membrane surface and two-dimensional molecular interactions within the tethered bilayer.
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Affiliation(s)
- G Woodhouse
- Cooperative Research Centre for Molecular Engineering and Technology, Australian Membrane and Biotechnology Research Institute, 126 Greville Street, Chatswood, NSW 2067, Australia
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663
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Protein patterning via radiation-assisted surface functionalization of conventional microlithographic materials. Colloids Surf A Physicochem Eng Asp 1999. [DOI: 10.1016/s0927-7757(98)00395-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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664
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van Oudenaarden A, Boxer SG. Brownian ratchets: molecular separations in lipid bilayers supported on patterned arrays. Science 1999; 285:1046-8. [PMID: 10446046 DOI: 10.1126/science.285.5430.1046] [Citation(s) in RCA: 223] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Brownian ratchets use a time-varying asymmetric potential that can be applied to separate diffusing particles or molecules. A new type of Brownian ratchet, a geometrical Brownian ratchet, has been realized. Charged, fluorescently labeled phospholipids in a two-dimensional fluid bilayer were driven in one direction by an electric field through a two-dimensional periodic array of asymmetric barriers to lateral diffusion fabricated from titanium oxide on silica. Diffusion spreads the phospholipid molecules in the orthogonal direction, and the asymmetric barriers rectify the Brownian motion, causing a directional transport of molecules. The geometrical ratchet can be used as a continuous molecular sieve to separate mixtures of membrane-associated molecules that differ in electrophoretic mobility and diffusion coefficient.
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Affiliation(s)
- A van Oudenaarden
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA
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665
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Burns CJ, Field LD, Morgan J, Ridley DD, Vignevich V. Preparation of cyclic disulfides from bisthiocyanates. Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(99)01333-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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666
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Burns CJ, Field LD, Hashimoto K, Petteys BJ, Ridley DD, Sandanayake KRAS. A Convenient Synthetic Route to Differentially Functionalized Long Chain Polyethylene Glycols. SYNTHETIC COMMUN 1999. [DOI: 10.1080/00397919908086236] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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667
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Affiliation(s)
- J Wang
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces 88003, USA
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668
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Song X, Swanson BI. Direct, ultrasensitive, and selective optical detection of protein toxins using multivalent interactions. Anal Chem 1999; 71:2097-107. [PMID: 10366891 DOI: 10.1021/ac981145f] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three highly sensitive, selective, and reagent-free optical signal transduction methods for detection of polyvalent proteins have been developed by directly coupling distance-dependent fluorescence self-quenching and/or resonant-energy transfer to the protein-receptor binding events. The ganglioside GM1, as the recognition unit for cholera toxin (CT), was covalently labeled with fluorophores and then incorporated into a biomimetic membrane surface. The presence of CT with five binding sites for GM1 causes dramatic change for the fluorescence of the labeled GM1. (1) In the scheme using fluorescence self-quenching as a signal-transduction mechanism, the fluorescence intensity drops significantly as a result of aggregation of the fluorophore-labeled GM1 on a biomimetic surface. (2) By labeling GM1 with a fluorescence energy transfer pair, aggregation of the labeled GM1 results in a decrease in donor fluorescence and an increase in acceptor fluorescence, providing a unique signature for selective protein-receptor binding. (3) In the third scheme, using the biomimetic surface as part of signal transduction and combining both fluorescence self-quenching and energy-transfer mechanisms to enhance the signal transduction, a signal amplification was achieved. The detection systems can reliably detect less than 0.05 nM CT with fast response (less than 5 min). This approach can easily be adapted to any biosensor scheme that relies on multiple receptors or co-receptors. The methods can also be applied to investigate the kinetics and thermodynamics of the multivalent interactions.
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Affiliation(s)
- X Song
- Chemical Science and Technology Division, Los Alamos National Laboratory, New Mexico 87545, USA.
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669
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Binder S, Levitt AM, Sacks JJ, Hughes JM. Emerging infectious diseases: public health issues for the 21st century. Science 1999; 284:1311-3. [PMID: 10334978 DOI: 10.1126/science.284.5418.1311] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Infectious diseases are the third leading cause of death in the United States and the leading cause worldwide. As the new millennium approaches, the public health community must replenish capacity depleted during years of inadequate funding while simultaneously incorporating new technologies and planning for the longer term. Among the challenges facing the public health community is the need for coordinated, global, multisectoral approaches to preventing and controlling complex infectious disease problems.
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Affiliation(s)
- S Binder
- Division of Parasitic Diseases, National Center for Infectious Diseases (NCID), Centers for Disease Control and Prevention (CDC), F-22, 4770 Buford Highway, NE, Atlanta, GA 30341, USA.
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670
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Ho WO, Krause S, McNeil CJ, Pritchard JA, Armstrong RD, Athey D, Rawson K. Electrochemical sensor for measurement of urea and creatinine in serum based on ac impedance measurement of enzyme-catalyzed polymer transformation. Anal Chem 1999; 71:1940-6. [PMID: 10361494 DOI: 10.1021/ac981367d] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enzyme-catalyzed polymer transformation with electrochemical ac impedance detection has been employed for the measurement of urea and creatinine in serum samples. A polymer, based on poly(methylvinyl ether)/maleic anhydride modified by esterification with n-octanol, which is stable at pH 7.4 and which is transformed rapidly in response to alkaline pH changes, was linked to enzymatic reactions between urease and urea or creatinine deiminase and creatinine to produce a disposable sensor system. The polymer was screen-printed onto interdigitated screen-printed carbon electrodes and the electrodes overlaid with absorbent pads containing the relevant enzyme. Application of serum samples, "spiked" with either urea or creatinine, resulted in rapid polymer transformation, and resultant changes in the capacitance of the polymer-coated electrodes were analyte-concentration dependent. Additional information on the mechanisms of polymer transformation was obtained from dynamic quartz crystal microbalance measurements.
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Affiliation(s)
- W O Ho
- Department of Chemistry, University of Newcastle upon Tyne, U.K
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671
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Gu LQ, Braha O, Conlan S, Cheley S, Bayley H. Stochastic sensing of organic analytes by a pore-forming protein containing a molecular adapter. Nature 1999; 398:686-90. [PMID: 10227291 DOI: 10.1038/19491] [Citation(s) in RCA: 495] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The detection of organic molecules is important in many areas, including medicine, environmental monitoring and defence. Stochastic sensing is an approach that relies on the observation of individual binding events between analyte molecules and a single receptor. Engineered transmembrane protein pores are promising sensor elements for stochastic detection, and in their simplest manifestation they produce a fluctuating binary ('on/off') response in the transmembrane electrical current. The frequency of occurrence of the fluctuations reveals the concentration of the analyte, and its identity can be deduced from the characteristic magnitude and/or duration of the fluctuations. Genetically engineered versions of the bacterial pore-forming protein alpha-haemolysin have been used to identify and quantify divalent metal ions in solution. But it is not immediately obvious how versatile binding sites for organic ligands might be obtained by engineering of the pore structure. Here we show that stochastic sensing of organic molecules can be procured from alpha-haemolysin by equipping the channel with an internal, non-covalently bound molecular 'adapter' which mediates channel blocking by the analyte. We use cyclodextrins as the adapters because these fit comfortably inside the pore and present a hydrophobic cavity suitable for binding a variety of organic analytes. Moreover, a single sensing element of this sort can be used to analyse a mixture of organic molecules with different binding characteristics. We envisage the use of other adapters, so that the pore could be 'programmed' for a range of sensing functions.
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Affiliation(s)
- L Q Gu
- Department of Medical Biochemistry & Genetics, Texas A&M University Health Science Center, College Station 77843-1114, USA
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672
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673
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Kasianowicz JJ, Burden DL, Han LC, Cheley S, Bayley H. Genetically engineered metal ion binding sites on the outside of a Channel's transmembrane beta-barrel. Biophys J 1999; 76:837-45. [PMID: 9929485 PMCID: PMC1300085 DOI: 10.1016/s0006-3495(99)77247-4] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
We are exploring the ability of genetically engineered versions of the Staphylococcus aureus alpha-hemolysin (alphaHL) ion channel to serve as rationally designed sensor components for analytes including divalent cations. We show here that neither the hemolytic activity nor the single channel current of wild-type alphaHL was affected by [Zn(II)] </= 1 mM. Binding sites for the divalent cations were formed by altering the number and location of coordinating side chains, e.g., histidines and aspartic acids, between positions 126 and 134, inclusive. Several mutant alphaHLs exhibited Zn(II)-induced current noise that varied with Zn(II) concentration. At a fixed divalent cation concentration, the current fluctuation kinetics depended on the analyte type, e.g., Zn(II), Cu(II), Ni(II), and Co(II). We also show that the ability of Zn(II) to change the mutant channel current suggests that the pore's topology is beta-sheet and that position 130 is near the turn at the trans mouth. Both conclusions are consistent with the crystal structure of WT-alphaHL oligomerized in detergent. Our results, in the context of the channel's crystal structure, suggest that conductance blockades were caused by Zn(II) binding to the outside surface of the pore. Thus, analyte-induced current blockades alone might not establish whether an analyte binding site is inside a pore.
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Affiliation(s)
- J J Kasianowicz
- National Institute of Standards and Technology, Biotechnology Division, Gaithersburg, Maryland 20899, USA.
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674
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Stora T, Lakey JH, Vogel H. Ionenkanalsteuerung in Transmembranrezeptorproteinen: funktionelle Aktivität in Träger-fixierten Lipidmembranen. Angew Chem Int Ed Engl 1999. [DOI: 10.1002/(sici)1521-3757(19990201)111:3<402::aid-ange402>3.0.co;2-d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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675
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Separovic F, Barker S, Delahunty M, Smith R. NMR structure of C-terminally tagged gramicidin channels. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1416:48-56. [PMID: 9889316 DOI: 10.1016/s0005-2736(98)00207-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A biotin group was covalently attached to the C terminus of gramicidin A (gA) through a linker arm comprising a glycine residue with either one (gAXB) or two caproyl groups (gAXXB). High-resolution two-dimensional NMR spectroscopy was used to determine the structure of these modified gA analogues and [Lys16]gramicidin A (gA-Lys) in sodium dodecyl-d25 sulphate micelles. Gated gA ion channels based on linking a receptor group to these gA analogues have been used recently as a component in a sensing device. The conformations of the gA backbones and amino acid side chains of lysinated gA and biotinylated gA in detergent micelles were found to be almost identical to that of native gA, i.e. that of an N-terminal to N-terminal (head to head) dimer formed by two right-handed, single-stranded beta 6.3 helices. The biotin tail of the gAXB and gAXXB and the lysine extremity of gA-Lys appeared to lie outside the micelle. Thus it appears that the covalent attachment of functional groups to the C terminus of gA does not disrupt the peptide's helical configuration. Further, single channel measurements of all three gA analogues showed that functioning ion channels were preserved within a membrane environment.
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Affiliation(s)
- F Separovic
- School of Chemistry, University of Melbourne, Parkville, VIC 3052, Australia.
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676
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677
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Partenskii MB, Dorman VL, Jordan PC. Membrane stability under electrical stress: A nonlocal electroelastic treatment. J Chem Phys 1998. [DOI: 10.1063/1.477691] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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678
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Lee JY, Park SM. Electrochemistry of Guest Molecules in Thiolated Cyclodextrin Self-Assembled Monolayers: An Implication for Size-Selective Sensors. J Phys Chem B 1998. [DOI: 10.1021/jp9828235] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jin-Young Lee
- Department of Chemistry and School of Environmental Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Su-Moon Park
- Department of Chemistry and School of Environmental Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea
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679
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Heyse S, Stora T, Schmid E, Lakey JH, Vogel H. Emerging techniques for investigating molecular interactions at lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1376:319-38. [PMID: 9804980 DOI: 10.1016/s0304-4157(98)00020-3] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- S Heyse
- Laboratoire de Chimie Physique des Polymères et Membranes, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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680
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Song X, Nolan J, Swanson BI. Optical Biosensor Based on Fluorescence Resonance Energy Transfer: Ultrasensitive and Specific Detection of Protein Toxins. J Am Chem Soc 1998. [DOI: 10.1021/ja981983r] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xuedong Song
- Chemical Science and Technology Division Life Science Division Los Alamos National Laboratory Los Alamos, New Mexico 87544
| | - John Nolan
- Chemical Science and Technology Division Life Science Division Los Alamos National Laboratory Los Alamos, New Mexico 87544
| | - Basil I. Swanson
- Chemical Science and Technology Division Life Science Division Los Alamos National Laboratory Los Alamos, New Mexico 87544
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681
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Poirson J, Vallet M, Bretenaker F, Le Floch A, Thépot JY. Resonant Cavity Gas-Phase Polarimeter. Anal Chem 1998; 70:4636-9. [DOI: 10.1021/ac980286e] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Jérôme Poirson
- Laboratoire d'Electronique Quantique-Physique des Lasers, Unité Mixte de Recherche du Centre National de la Recherche Scientifique 6627, Université de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - Marc Vallet
- Laboratoire d'Electronique Quantique-Physique des Lasers, Unité Mixte de Recherche du Centre National de la Recherche Scientifique 6627, Université de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - Fabien Bretenaker
- Laboratoire d'Electronique Quantique-Physique des Lasers, Unité Mixte de Recherche du Centre National de la Recherche Scientifique 6627, Université de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - Albert Le Floch
- Laboratoire d'Electronique Quantique-Physique des Lasers, Unité Mixte de Recherche du Centre National de la Recherche Scientifique 6627, Université de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - Jean-Yves Thépot
- Laboratoire d'Electronique Quantique-Physique des Lasers, Unité Mixte de Recherche du Centre National de la Recherche Scientifique 6627, Université de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
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682
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Abstract
Current biosensor developments can be summarised by different trends. For traditional enzymatic biosensors such as glucose sensors, steady improvements of well known basic principles have been made in order to achieve better sensor stability. On the other hand, new affinity sensors such as nucleic acid sensors, transmembrane sensors, and sensors utilising whole cells or even cell networks have become of increasing interest. New ways to miniaturise biosensors and to control their interfaces down to the molecular level have been introduced (the bioelectronics approach). High-throughput screening based on various signal transduction principles has become of increasing importance.
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Affiliation(s)
- C Ziegler
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Germany.
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683
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Schmidt EK, Liebermann T, Kreiter M, Jonczyk A, Naumann R, Offenhäusser A, Neumann E, Kukol A, Maelicke A, Knoll W. Incorporation of the acetylcholine receptor dimer from Torpedo californica in a peptide supported lipid membrane investigated by surface plasmon and fluorescence spectroscopy. Biosens Bioelectron 1998; 13:585-91. [PMID: 9828354 DOI: 10.1016/s0956-5663(98)00013-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The dimer species (M(r) 580,000) of the nicotinic acetylcholine receptor, isolated from the electric organ of Torpedo californica, was incorporated into a thiopeptide supported lipid bilayer. The incorporation was achieved by fusion of liposomes with reconstituted receptor onto a gold-supported thiopeptide lipid monolayer. Surface plasmon resonance spectroscopy (SPS) was used to monitor in real time the fusion process as well as the specific binding of the antagonist alpha-bungarotoxin. A recently developed extension of SPS offering enhanced sensitivity and specificity, surface plasmon fluorescence spectroscopy (SPFS), was then used to monitor subsequent binding of the monoclonal WF6 and polyclonal antibody, respectively. The latter was fluorescence labeled with Cy5. The different binding assays indicate the successful incorporation of the receptor in the lipid bilayer.
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Affiliation(s)
- E K Schmidt
- Max Planck Institute for Polymer Research, Mainz, Germany
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684
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N,N′-Disuccinimidyl carbonate as a coupling agent in the synthesis of thiophospholipids used for anchoring biomembranes to gold surfaces. Tetrahedron 1998. [DOI: 10.1016/s0040-4020(98)00674-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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685
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Motesharei K, Myles DC. Molecular Recognition on Functionalized Self-Assembled Monolayers of Alkanethiols on Gold. J Am Chem Soc 1998. [DOI: 10.1021/ja973166h] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kianoush Motesharei
- Contribution from the Department of Chemistry & Biochemistry, University of California, Los Angeles, California 90095-1569
| | - David C. Myles
- Contribution from the Department of Chemistry & Biochemistry, University of California, Los Angeles, California 90095-1569
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686
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687
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Fishman HA, Greenwald DR, Zare RN. Biosensors in chemical separations. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 1998; 27:165-98. [PMID: 9646866 DOI: 10.1146/annurev.biophys.27.1.165] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Identification of biomolecules in complex biological mixtures represents a major challenge in biomedical, environmental, and chemical research today. Chemical separations with traditional detection schemes such as absorption, fluorescence, refractive index, conductivity, and electrochemistry have been the standards for definitive identifications of many compounds. In many instances, however, the complexity of the biomixture exceeds the resolution capability of chemical separations. Biosensors based on molecular recognition can dramatically improve the selectivity of and provide biologically relevant information about the components. This review describes how coupling chemical separations with online biosensors solves challenging problems in sample analysis by identifying components that would not normally be detectable by either technique alone. This review also presents examples and principles of combining chemical separations with biosensor detection that uses living systems, whole cells, membrane receptors, enzymes, and immunosensors.
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Affiliation(s)
- H A Fishman
- Department of Chemistry, Stanford University, California 94305, USA.
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688
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689
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Wallace BA. Recent Advances in the High Resolution Structures of Bacterial Channels: Gramicidin A. J Struct Biol 1998; 121:123-41. [PMID: 9618340 DOI: 10.1006/jsbi.1997.3948] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gramicidin is a polypeptide antibiotic which forms dimeric channels specific for the transport of monovalent cations across membranes. It adopts several different conformations, most notably double helical (pore) and helical dimer (channels) forms, which have very different structural and functional characteristics. This review focuses on recent high resolution structure determinations of both the pore and channel forms of the molecule by X-ray crystallographic and/or NMR spectroscopic techniques. It discusses the structural consequences of binding ions and the location of ion binding sites and how the structures are related to the conductance properties of the molecule. This relatively simple molecule is probably the best characterized ion channel (both structurally and functionally) and has, to date, been the principal proving-ground for many of our ideas about the molecular nature of ion conduction in membranes. Copyright 1998 Academic Press.
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Affiliation(s)
- BA Wallace
- Department of Crystallography, Birkbeck College, University of London, London, WC1E 7HX, United Kingdom
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690
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Affiliation(s)
- James L. Anderson
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - Louis A. Coury
- Bioanalytical Systems Inc., 2701 Kent Avenue, West Lafayette, Indiana 47906-1382
| | - Johna Leddy
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242
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691
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Song X, Nolan J, Swanson BI. Optical Signal Transduction Triggered by Protein−Ligand Binding: Detection of Toxins Using Multivalent Binding. J Am Chem Soc 1998. [DOI: 10.1021/ja980246s] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xuedong Song
- Chemical Science and Technology Division Life Science Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - John Nolan
- Chemical Science and Technology Division Life Science Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - Basil I. Swanson
- Chemical Science and Technology Division Life Science Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
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692
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Abstract
Biosensors exploit the remarkable specificity of biomolecular recognition to provide analytical tools that can measure the presence of a single molecular species in a complex mixture. A new strategy is emerging in the development of biosensor technologies: molecular-engineering techniques are being used to adapt the properties of proteins to simple, generic detector instrumentation, rather than adapting instruments to the unique requirements of a natural molecule.
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Affiliation(s)
- H W Hellinga
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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693
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Gupta VK, Skaife JJ, Dubrovsky TB, Abbott NL. Optical amplification of ligand-receptor binding using liquid crystals. Science 1998; 279:2077-80. [PMID: 9516101 DOI: 10.1126/science.279.5359.2077] [Citation(s) in RCA: 386] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Liquid crystals (LCs) were used to amplify and transduce receptor-mediated binding of proteins at surfaces into optical outputs. Spontaneously organized surfaces were designed so that protein molecules, upon binding to ligands hosted on these surfaces, triggered changes in the orientations of 1- to 20-micrometer-thick films of supported LCs, thus corresponding to a reorientation of approximately 10(5) to 10(6) mesogens per protein. Binding-induced changes in the intensity of light transmitted through the LC were easily seen with the naked eye and could be further amplified by using surfaces designed so that protein-ligand recognition causes twisted nematic LCs to untwist. This approach to the detection of ligand-receptor binding does not require labeling of the analyte, does not require the use of electroanalytical apparatus, provides a spatial resolution of micrometers, and is sufficiently simple that it may find use in biochemical assays and imaging of spatially resolved chemical libraries.
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Affiliation(s)
- V K Gupta
- Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA
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694
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Marvin JS, Hellinga HW. Engineering Biosensors by Introducing Fluorescent Allosteric Signal Transducers: Construction of a Novel Glucose Sensor. J Am Chem Soc 1998. [DOI: 10.1021/ja972993f] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jonathan S. Marvin
- Contribution from the Department of Biochemistry, Box 3711, Duke University Medical Center, Durham, North Carolina 22710
| | - Homme W. Hellinga
- Contribution from the Department of Biochemistry, Box 3711, Duke University Medical Center, Durham, North Carolina 22710
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695
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Weiss LA, Sakai N, Ghebremariam B, Ni C, Matile S. Rigid Rod-Shaped Polyols: Functional Nonpeptide Models for Transmembrane Proton Channels. J Am Chem Soc 1997. [DOI: 10.1021/ja973126d] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Linnea A. Weiss
- Contribution from the Department of Chemistry, Georgetown University, Washington, D.C. 20057-1227
| | - Naomi Sakai
- Contribution from the Department of Chemistry, Georgetown University, Washington, D.C. 20057-1227
| | - Bereket Ghebremariam
- Contribution from the Department of Chemistry, Georgetown University, Washington, D.C. 20057-1227
| | - Chiyou Ni
- Contribution from the Department of Chemistry, Georgetown University, Washington, D.C. 20057-1227
| | - Stefan Matile
- Contribution from the Department of Chemistry, Georgetown University, Washington, D.C. 20057-1227
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696
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Abstract
Significant advances in the understanding of the mechanisms of artificial transporters appeared in the past year which provide insights into natural transporters and suggest directions for regulation of transport. Parallel developments in the control of bilayer formation and molecular recognition by synthetic lipids have led to simple mimics of 'whole cell' types of processes.
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Affiliation(s)
- T M Fyles
- Department of Chemistry, University of Victoria, Box 3065, Victoria BC, Canada V8W 3P6
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697
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Houston JG, Banks M. The chemical-biological interface: developments in automated and miniaturised screening technology. Curr Opin Biotechnol 1997; 8:734-40. [PMID: 9425665 DOI: 10.1016/s0958-1669(97)80128-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The rapidly changing developments in genomics and combinatorial chemistry, generating new drug targets and large numbers of compounds, have caused a revolution in high-throughput screening technologies. Key to this revolution has been the introduction of robotics and automation, together with new biological assay technologies (e.g., homogeneous time resolved fluorescence). With ever increasing workloads, together with economic and logistical constraints, miniaturisation is rapidly becoming essential for the future of high-throughput screening and combinatorial chemistry. This is evident from the introduction of high-density microtitre plates, small volume liquid handling robots and associated detection technology.
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Affiliation(s)
- J G Houston
- Lead Discovery Unit, Glaxo Wellcome Medicines Research Centre, Stevenage, Hertfordshire, UK.
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698
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Motesharei K, Ghadiri MR. Diffusion-Limited Size-Selective Ion Sensing Based on SAM-Supported Peptide Nanotubes. J Am Chem Soc 1997. [DOI: 10.1021/ja9727171] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kianoush Motesharei
- Contribution from the Departments of Chemistry & Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037
| | - M. Reza Ghadiri
- Contribution from the Departments of Chemistry & Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037
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699
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700
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