PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “biosensor”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
PubMed2002

Flow-mediated on-surface reconstitution of G-protein coupled receptors for applications in surface plasmon resonance biosensors.

To facilitate biosensor studies of G-protein coupled receptors (GPCR) and other membrane proteins, reliable methods for preparation of sensor surfaces with high protein density are required. We present here a method for the easy and rapid immobilization and reconstitution of GPCR on carboxylated dextran surfaces modified with long alkyl groups. Following amine coupling of the detergent-solubilized receptor, lipid/detergent-mixed micelles were adhered as they were injected over the immobilized surface, taking advantage of the integrated flow cells. The detergent was eluted in the subsequent buffer flow and the remaining lipid formed a bilayer on the chip surface. With this procedure, rhodopsin was functionally reconstituted in a lipid environment in approximately 1 min. This method can also be used for the easy formation of pure supported lipid bilayers for use in model membrane interaction studies.

Heterotrimeric GTP-Binding Proteins↗
PubMed2002

Use of optical biosensor technology to study immunological cross-reactivity between different sulfonamide drugs.

Adverse reactions to medications account for a substantial number of hospitalizations and in some cases fatalities. The nature of the many drug-drug interactions caused by the inhibition of drug-metabolizing enzymes can now be predicted and examined with a greater deal of accuracy due to research developments in the understanding of the drug-metabolizing enzymes. However, the more troubling aspects of drug-drug interactions are the idiosyncratic reactions that are unpredictable and quite often life-threatening. These reactions are often caused by a prior sensitization of a person's immune system to a given drug or class of drugs. The following work offers a technique to examine in a medium-throughput system the cross-reactivity of drugs to antibodies in order to predict if structures share the same antigenic potential toward a sensitized individual. Two commercially important sulfonamide drugs, sulfamethazine and furosemide, were taken and their binding to their respective antibodies were tested in the presence of other structurally related sulfonamide drugs. The BIACORE 3000 biosensor was used for the study and the solution-phase equilibrium assay principle was employed. The data obtained help us determine which drugs can react, and to what extent, with sulfamethazine and furosemide, giving rise to possible allergic or hypersensitivity reactions. Though sulfamethazine and furosemide were used in this study; this principle and methodology can be applied to study any drug molecule-antibody pair.

Biosensing Techniques↗
PubMed1999

Detection of molecular interactions by using a new peptide-displaying bacteriophage biosensor.

Foreign peptides fused to the carboxy terminus of P22 tailspike protein are solvent-exposed and highly antigenic when displayed on the surface of infectious virus particles. Binding of an anti-peptide specific Fab antibody fragment enhances the infectivity of chimeric bacteriophage particles in a titre-dependent fashion. Although the precise molecular basis of this enhanced infectivity remains unclear, experimental data and modelling approaches suggest that the antibody binding might restore conformational impairments in the assembled tail protein affecting its activity and performance during infection. These results suggest that in addition to free enzymes, peptide-displaying bacteriophages could be engineered as new biosensors to detect molecular interactions by using natural viral enzymes critical for cell infection.

Bacteriophage P22↗
PubMed2000

Optical biosensor study of ternary complex formation in a cytochrome P4502B4 system.

The optical biosensor method was used for the revelation of ternary complexes, formed by the full-length NADPH-cytochrome P450 reductase (d-Fp) and cytochromes P4502B4 (d-2B4) and b5 (d-b5) in the course of their interactions within the reconstituted d-2B4-containing system. Based on the lack of competition between d-b5 and d-Fp for the binding sites on immobilized 2B4 (3) as well as on the analysis of data obtained in the three proteins' dissociation reactions, the possibility of formation of ternary complexes through the interactions between membranous hydrophobic fragments of proteins was substantiated. All the complexes obtained were productive.

Animals↗
PubMed2001

Application of different surface plasmon resonance biosensor chips to monitor the interaction of the CaM-binding site of nitric oxide synthase I and calmodulin.

Surface plasmon resonance biosensors depend on modified gold surfaces to allow immobilization of proteins or peptides for interaction analysis. We investigated sensor chip surfaces that differ in the geometry of the immobilization matrix: two contain a three-dimensional coupling matrix and two have a surface with immobilization sites on a two-dimensional plane. Properties of sensor chips were compared by studying the interaction of calmodulin with a peptide representing the calmodulin-binding site of nitric oxide synthase I. Apparent K(D) values were determined by three different procedures in order to apply tests for self-consistency. At low surface densities (5-8 fmol/mm(2)) on three of the four tested surfaces, estimated K(D) values were within one order of magnitude and similar to the value found in solution (K(D) = 1-3 nM). When immobilization densities were increased by one to two orders of magnitude, apparent association rate constants were less distorted on a flat carboxymethylated surface than on dextran-coated sensor chips.

Amino Acid Sequence↗
PubMed2002

Optical algal biosensor using alkaline phosphatase for determination of heavy metals.

A biosensor is constructed to detect heavy metals from inhibition of alkaline phosphatase (AP) present on the external membrane of Chlorella vulgaris microalgae. The microalgal cells are immobilized on removable membranes placed in front of the tip of an optical fiber bundle inside a homemade microcell. C. vulgaris was cultivated in the laboratory and its alkaline phosphatase activity is strongly inhibited in the presence of heavy metals. This property has been used for the determination of those toxic compounds.

Alkaline Phosphatase↗
PubMed2005

Preliminary study of simultaneous multi-anticoagulant deficiency diagnosis by fiber optic multi-analyte biosensor.

Protein C (PC), protein S (PS), antithrombin III, and plasminogen are four important anticoagulants in blood plasma. Deficiency of any of these biomolecules may lead to thrombo-embolic complications including lung embolism, heart attack, and stroke. A multi-factor sensing system is beneficial for identifying the cause of abnormal blood clotting more effectively, rapidly, and cost-effectively. As an initial effort toward simultaneous multi-anticoagulant detection, a PC and PS dual-sensing system has been under development in our research group. A fiberoptic PC biosensor utilizing fluorophore-mediated sandwich immunoassay was already developed for rapid (-5 minutes) PC deficiency diagnosis. After a single PS sensor was developed for the PS deficiency diagnosis, the two sensors were connected in series to form a dual-sensing system. The cross-reactivity between the analytes and the sensors was found to be minimal. For easier sensing operation, a mixture of fluorophore-linked anti-PC and anti-PS was applied. The results showed that the mixture can be used with a slight signal reduction. When PC and PS was mixed in a sample, the signal intensity was decreased by approximately 5% for both sensors. A study is currently being performed to overcome the signal reduction by increasing the flow velocity and incubation time.

Animals↗
PubMed2003

Effects of blocking buffers and plasma proteins on the protein C biosensor performance.

Protein C (PC) deficiency can lead to abnormal thrombus formation in blood vessels, obstructing oxygen and nutrient transport to various organs or tissues. Quantifying PC amount in blood plasma usually takes long time, is difficult and expensive due to its low concentration and other homologous proteins in it. A fiber-optic immunosensor has been under development for several years for the PC real-time assay. In this study, blocking buffers have been examined to reduce the noise caused by non-specific adsorption. Ethanolamine was found to reduce the noise significantly. The effect of various PC homologues (factors II, VII, IX, and X) on the biosensor performance was investigated. The sensor showed little cross reactivity with these homologues. Human serum albumin (HSA) in the sample decreased the signal intensity. However, PC could be still quantified in samples with HSA at the physiological level.

Biosensing Techniques↗
PubMed1998

Preliminary study of biosensor optimization for the detection of protein C.

Methods to develop an immuno-optical biosensor for the detection and monitoring of Protein C (PC) concentrations are described. A tapered quartz fiber is enclosed in a glass tube (capacity approximately 300 microliters) and monoclonal antibody against PC (anti-PC) is immobilized on the surface of this fiber. PC within a sample, when injected into the chamber, will bind to the anti-PC in a specific reaction. The system is then probed with a fluorophore tagged secondary antibody against PC, also binding to PC in a specific reaction. Excitation light is applied through the fiber, and the amount of fluorescence is correlated with the PC concentration in the sample. This study offers encouraging results for the detection of PC deficiency in real-time.

Antibodies, Monoclonal↗
PubMed1988

Development of membrane-based biosensors: measurement of current from photocycling bacteriorhodopsin on patch clamp electrodes.

Our initial work toward developing membrane protein-based biosensors has involved use of bacteriorhodopsin (BR) as a model membrane protein. BR was incorporated into liposomes of a polymerizable lecithin, and was shown to pump protons in response to illumination both before and after polymerization of the lipids. In the work described in this paper, BR was first reincorporated in liposomes of asolectin by consonication with purple membrane. The liposomes, which sustained the function of the protein, were used to form a monolayer at the air-water interface. This monolayer was transferred as a bilayer onto patch electrode. When illuminated with a pulse of 514.5-nm light the lipid/protein patch produced a current spike into the pipette corresponding to events no later than the generation of the 412-nm intermediate, probably caused by pumping of protons across the patch membrane. The experiment demonstrates not only the extreme sensitivity of amperometric detection, but also a small tendency for membrane proteins to preferentially orient in this configuration.

Bacteriorhodopsins↗
PubMed1997

Förster energy transfer in ultrathin polymer layers as a basis for biosensors.

A method of detecting the binding of analyte molecules to biospecific receptors, like antibodies, is described. Förster energy transfer is used in connection with monomolecular organic films. The films are built up from pre-polymerized materials using the Langmuir-Blodgett or self-assembly techniques. Fluorescent dyes (as energy transfer donors) as well as reactive groups for covalent immobilization of protein receptors are integrated into the polymers. Several different methods for immobilizing biomolecules are described, including the use of protein A and the biotin/streptavidin couple. The studies suggest that the combination of Förster transfer and ultrathin organic films can be used for the construction of biosensors working either by displacement or by competitive assays. The mannose/concanavalin A, digoxin/antibody, and mouse immunoglobulin G/antibody systems are investigated. Further, a simplified meter optimized for measuring the fluorescence ratio at two wavelengths is described.

Antibodies↗
PubMed1997

Commercial biosensors for medical application.

Biosensors today are represented on the market worldwide by an increasing number of enzyme electrodes working in various areas of medical diagnostics, and by a few opto-immunosensor-based analytical systems suited for protein research in pharmaceutical chemistry. Enzyme electrodes for metabolites and enzyme activities have been commercially available for about 20 years. Such sensors are successfully applied in laboratory autoanalyzers, point-of-care-systems, patient self-monitoring disposable probes, intensive care analyzers, and for on-line monitoring of diabetics.

Biosensing Techniques↗
PubMed1986

[Biosensors].

By the combination of transducers (thermistors, selective electrodes, field-effect transistors, optical systems) with immobilized enzymes or antibodies specific sensors for biologically relevant substances are obtained. The construction, ranges, of linearity, response times and stability of biosensors are demonstrated. Examples are given for their application in clinical analysis and fermentation control. Finally limits and future possibilities are discussed.

Antibodies↗
PubMed1990

Lactate and glucose electrochemical biosensors for the evaluation of the aerobic and anaerobic threshold in runners.

Lactate and glucose are measured in whole blood of athletes running on a treadmill by using two extracorporeal electrochemical biosensors. The lactate sensor was fixed to an endocrine artificial pancreas (Betalike) which had been used in previous extracorporeal experiments. The lactate sensor gave a signal which resulted in a well defined curve that allowed the evaluation of the aerobic as well as the anaerobic threshold. The results obtained with the glucose sensor supported the theory that muscle anaerobic glycolysis is dependent on muscle glycogen rather than on blood glucose.

Adult↗
PubMedDate not supplied

Glucose biosensors based on oxygen electrode with sandwich-type membranes.

A glucose biosensor based on an amperometric oxygen electrode has been developed. Polycarbonate and Silastic membranes were assembled (glued together) to form a multilayer sandwich glucose diffusion barrier. The effects of the glue layer composition and thickness of the Silastic membrane on sensor response parameters have been investigated in order to optimize the sensor. The parameters measured were the sensitivity, the concentration range of the linear dependence of the sensor response to glucose, and the long-term operation time. The sensors with the sandwich-type glucose diffusion membrane (Silastic membrane prepared from 20% Silastic suspension, glue layer prepared from polyurethane, 0.5 w/v % in ThF solution and standard polycarbonate membrane) demonstrated linearity of response up to 520 mg/dl glucose at 25 degrees C and up to 400 mg/dl at 37 degrees C. These sensor showed good reproducibility of response without significant interference effects (from 1 to 5% of the background current value). The long-term continuous operational time of the sensors was over 40 days at 37 degrees C, and over 60 days at 25 degrees C.

Animals↗
PubMed1996

Antigen-antibody diffusion-limited binding kinetics for biosensors. A fractal analysis.

A fractal analysis is made for antigen-antibody binding kinetics for different biosensor applications available in the literature. Both types of examples are considered wherein: (1) the antigen is in solution and the antibody is immobilized on the fiberoptic surface, and (2) the antibody is in solution and the antigen is immobilized on the fiberoptic surface. For example, when the antibody is immobilized on the surface, an increase in the antigen Clostridium botulinum toxin A concentration in solution leads to (1) a decrease in the fractal dimension value or state of disorder, and (2) a higher rate constant for binding on the fiberoptic surface. An analysis of the effect of the influence of different parameters on the fractal dimension values for a particular example, such as varying treatments or incubation procedures, helps provide insights into the conformational states and reactions occurring on the fiberoptic surface. The analysis of the different example taken together provides novel physical insights into the state of "disorder" and reactions occurring on the surface. Such types of analysis should help contribute toward manipulating the reactions occurring on the fiberoptic surfaces in desired directions.

Antigen-Antibody Reactions↗
PubMed1992

Glucose biosensor using glucose oxidase immobilized in polyaniline.

A biosensor for glucose utilizing kinetics of glucose oxidase (EC 1.1.3.4.) was developed. The enzyme was immobilized on polyaniline by covalent bonding, using glutaraldehyde as a bifunctional agent. The system showed a linear response up to 2.2 mM of glucose with a response time of 2.5-4.0 min. In addition, the immobilized enzyme had a higher activity between pH 6.5 and 7.5. The system retained 50% of its activity after 30 d of daily use. The optical absorption spectra of the polyaniline/glucose oxidase electrode after glucose had been added to the buffer solution showed that the absorption band around 800 nm had changed considerably when glucose was allowed to react with the electrode. This optical variation makes polyaniline a very promising polymer for use as a support in optical sensor for clinical application.

Aniline Compounds↗