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 55 records · Page 3Linked to original sources

PubMed1992

Biosensors and enzyme immobilized electrodes.

A biosensor is a device which consists of a biological sensing element connected to a transducer. The transducer can be electronic, optical, electrical, etc. This emerging technology offers us a powerful tool which is radically altering our approach to analytical methods. It was realised that enzymes are natural sensors on account of their highly selective nature. Much of the impetus to the work has come from medical requirements. Instant analysis of clinical samples has an obvious appeal to physicians and patients alike. Of particular interest is the possibility of continuous 'in-vivo' monitoring of metabolites, drugs and proteins using miniature, portable systems. In recent years, there has been a growing demand for biosensors in the fields of veterinary science, animal husbandry, the food industry and environmental monitoring. However, the possibility of successful application rests upon future developments. Increasing attention will have to be paid to the engineering of both the basic components and the device on the whole. New biochemical reactions will either have to be discovered or engineered through genetic manipulation or chemical techniques. Optimization of response time, selectivity, stability and low costs should receive priority considerations.

Biosensing Techniques↗

PubMed1990

A fast responding fibre optic glucose biosensor based on an oxygen optrode.

A fast responding glucose biosensor for the continuous determination of glucose is presented. The biosensor is based on an oxygen optrode, which measures the consumption of oxygen via dynamic quenching of the fluorescence of an indicator by molecular oxygen. Glucose oxidase (GOD) is immobilised onto the surface of this oxygen optrode by adsorption to carbon black and by crosslinking with glutardialdehyde. Carbon black is used as an optical isolation to protect the optrode from the interference of ambient light and sample fluorescence. The measurements were performed in a flow through cell with air saturated glucose standard solutions (phosphate buffered saline pH 6.9). The effect of four different qualities of GOD in relation to response times (the time required to reach 90% of the steady-state signal, tau 90, was 8-60 s, the linear analytical range (0.01 to 2 mM glucose) and the long-term stability (tau 1/2 was 1-20 weeks) were investigated. A simple device is presented capable of enlarging the analytical range up to 200 mM glucose concentration.

Biosensing Techniques↗

PubMed1990

Piezoelectric crystal biosensors.

The recent development of piezoelectric devices as biosensors is reviewed. Biological materials, like enzymes, lipids, antibodies and antigens, have been used as specific coatings and were utilized for the determination of different substrates. Methods of protein coating and several applications are reported including microgravimetric immunoassays, microbial assays, DNA hybridization, enzyme detections and gas phase biosensors. Although the piezoelectric immunochemical sensor is convenient to use and very promising, a thorough understanding of the different phenomena associated with crystals frequency measurement in biological reactions is still lacking and deserves further investigation.

Antibodies↗

PubMed1991

The potential role of biosensors in the food and drink industries.

Despite their apparent potential as analytical tools in the food and drink industries, only a few biosensors are used routinely. This article describes the development of biosensors for these sectors and discusses the technical and economic problems of applying this technology to the monitoring of food and drink products.

Beverages↗

PubMed1991

An FIA biosensor system for the determination of phosphate.

A flow injection analysis (FIA) biosensor system for the determination of phosphate was constructed using immobilized nucleoside phosphorylase and xanthine oxidase and an amperometric electrode (platinum vs silver/silver chloride, polarized at 0.7 V). When a phosphate-containing sample was injected into the detection cell, phosphate reacted with inosine in the carrier buffer to produce hypoxanthine and ribose-1-phosphate in the presence of nucleoside phosphorylase. Hypoxanthine was then oxidized by xanthine oxidase to uric acid and hydrogen peroxide, which were both detected by the amperometric electrode. The response of the FIA biosensor system was linear up to 100 microM phosphate, with a minimum detectable concentration of 1.25 microM phosphate. Each assay could be performed in 5-6 min and the system could be used for about 160 repeated analyses. This system was applicable for the determination of phosphate in various food products and plasma, and the results obtained agreed well with those of the enzymatic assay.

Biosensing Techniques↗

PubMed1991

Internal supply of coenzyme to an amperometric glucose biosensor based on a chemically modified electrode.

A biosensor for glucose using glucose dehydrogenase immobilized on a chemically modified graphite electrode was supplied with coenzyme, nicotinamide adenine dinucleotide (NAD+), through pores in the material. A graphite rod was hollowed out, leaving 0.3 mm at the end contacting the solution, filled with 10 mM NAD+ and pressurized. The response factor was 40% of that obtained when 2 mM NAD+ was mixed with the sample solution in a flow system. The coenzyme consumption was 11 microliters h-1 representing a 500-fold saving compared to supply through the bulk solution. The biosensor had a linear calibration curve from the detection limit, 1 microM, to 2 mM glucose and a repeatability of 0.3%. The graphite electrode was modified by adsorption of a bis-(benzophenoxazinyl)-terephthaloyl derivative in order to be able to oxidize NADH at 0 mV versus Ag/AgCl, 0.1 M KCl.

Biosensing Techniques↗

PubMed1992

A chemiluminescence fiber-optic biosensor system for the determination of glutamine in mammalian cell cultures.

A chemiluminescence fiber-optic biosensor system has been developed for determining glutamine in hybridoma cell cultures producing monoclonal antibodies against viral surface antigens. Glutaminase and glutamate oxidase (GLO) were immobilized onto aminopropyl glass beads via glutaraldehyde activation separately and packed in a column. Two separate columns containing immobilized GLO and catalase were placed upstream to eliminate endogenous glutamate. In the presence of ferricyanide, luminol reacted with hydrogen peroxide released from the enzymatic reactions to produce a chemiluminescence (CL) light signal which was detected and quantitated with a fiber-optic system. In combination with flow injection analysis it was possible to process samples virtually identically, thus avoiding difficulties in reproducing the CL signal. There was an excellent linear relationship between the CL response and standard glutamine concentration in the range 10(-6) to 10(-3) M. A complete analysis could be performed in 2 min including sampling and washing. Each immobilized enzyme column was stable for at least 300 repeated analyses without any loss of activity. When the biosensor system was used for the determination of glutamine in spent mammalian cell cultures, the values obtained compared well with those of high-performance liquid chromatography, thus validating the applicability of the CL fiber-optic system.

Animals↗

PubMed1992

Biosensors for environmental monitoring.

In this article we will outline several biosensor applications which may fill existing technology gaps in the area of environmental monitoring. The requirements for these environmental biosensors, as well as difficulties in commercialization, are also addressed.

Biosensing Techniques↗

PubMed1992

A single mode fibre-optic evanescent wave biosensor.

This paper reports experimental developments in the construction and operation of a single-mode fibre-optic evanescent wave biosensor using an exposed core silica single-mode fibre embedded in a silica block. The device was able to monitor the concentration of a blue dye, Procion Blue MX-G, in overlayers of various refractive indices. The practicality of such a biosensor has been demonstrated with a colorimetric enzyme assay system. Penicillin G in the 0-0.4 mM concentration range was monitored at 633 nm by the decoloration of the starch-iodine reagent when Bacillus cereus penicillinase was immobilized over the exposed core of the monomode fibre.

Biosensing Techniques↗

PubMed2026

A smartphone-integrated plasmonic biosensor for amplification-free detection of African swine fever virus.

African Swine Fever Virus (ASFV) poses a catastrophic threat to global swine production, with recent outbreaks across Europe, Asia, and the Caribbean, significantly elevating the biosecurity risk to the United States' billion-dollar pork industry. Current diagnostic gold standards are laboratory-dependent and introduce critical delays in outbreak response. To address this gap, a plasmonic biosensor based on functionalized gold nanoparticles (GNPs) was developed for the rapid, amplification-free detection of ASFV. GNPs were surface-functionalized with 11-mercaptoundecanoic acid (MUDA) and combined in situ with ASFV-specific oligonucleotide probes targeting a conserved region of the p72 (B646L) gene. The detection mechanism relies on acid-induced aggregation: hybridization of target ASFV DNA to the probe generates a rigid duplex that shields the nanoparticles from acid-induced destabilization, maintaining a ruby-red color, whereas in the absence of target DNA the GNPs aggregate, producing a visible red-to-blue color shift. The optimized plasmonic biosensor demonstrated 100% analytical specificity, with no cross-reactivity against a panel of 19 non-target bacterial genomic DNA samples representative of the swine environment. Detection limits determined by the IUPAC 3σ criterion were 285 copies per reaction for Probe 1 and 402 copies per reaction for Probe 2, within the same order of magnitude as the qPCR reference assay run on the same dilution series (approximately 312 copies per reaction) under the experimental conditions used here. A smartphone-based Bio-Analytics App employing an RGB color-conversion algorithm served as a quantitative reader, yielding signal-to-noise ratios (S/N) that strongly correlated with benchtop spectrophotometric readings (A520/A620 ratio, R2 = 0.96) and achieved diagnostic concordance with qPCR binary calls. This platform offers a robust and low-cost (∼$2 per test), amplification-free approach to ASFV screening with potential for point-of-need deployment, subject to future validation in clinical specimens.

Journal Article↗

PubMed1987

Optical biosensors for immunoassays: the fluorescence capillary-fill device.

This paper reports, for the first time, details of a novel type of optical biosensor for immunoassays, the fluorescence capillary-fill device (FCFD). This is based on a straightforward adaptation of the technology used to mass manufacture liquid-crystal display (LCD) cells to give cheap disposable immunosensors. These merely require contact by the sample to give a result in about a minute, and use certain principles of optical fibres and waveguides to avoid the need for operator attention, for physical separation methods or for washing steps. After a very brief introductory review and classification of optical biosensors, the main features of the FCFD and its associated instrumentation are described. The optical characteristics of the FCFD are then described, followed by accounts of the immunoassay method, the measurement system used in the experiments, the fabrication of FCFD sensors and a detailed description of the design of a competitive immunoassay for human immunoglobulin G (hIgG). The experimental details and the results of a first attempt at such an assay are then presented and discussed. It is concluded that the demonstration of this assay is a significant achievement, because the format of the FCFD, its manufacturing process and its instrumentation are completely novel. Certain problem areas have been identified and quantified; intended further work on these is outlined.

Animals↗

PubMed1987

Biosensors in process control.

Improvement in bioprocess control will require development of monitors for a wide range of cell-growth and downstream-process parameters. These requirements are examined in terms of the development and application of biosensor devices and physical measurement techniques. Acoustic, dielectric and laser light scattering techniques are discussed primarily as monitors and analysers for biomass parameters. Developments with biosensor devices are discussed in terms of their application in membrane sampling-flow analysis probes and the potential of more direct biosensing principles.

Animals↗

PubMed1989

Biosensors.

Biosensors are analytical devices that respond selectively to analytes in an appropriate sample and convert their concentration into an electrical signal via a combination of a biological recognition system and an electrochemical, optical or other transducer. Such devices will find application in medicine, agriculture, environmental monitoring and the bioprocessing industries. The last few years have seen great advances in the design of sensor architectures, the marriage of biological systems with monolithic silicon and optical technologies, the development of effective electron-transfer systems and the configuration of direct immunosensors. Recent progress in these areas has already led to the introduction of new-generation biosensors into the competitive diagnostics market place.

Biosensing Techniques↗

PubMed1991

Biosensor applications to antitachycardia devices.

Current arrhythmia detection algorithms are unable to adequately distinguish stable from unstable tachycardias; therefore application of a biosensor to antitachycardia devices has been proposed to improve their performance. Right heart pressures and impedance have been investigated for incorporation into these systems. Integration of other parameters (oxygen saturation, preejection period, pH, cardiac output, flow, and temperature) into these devices might also prove useful. The status of these biosensor arrhythmia detection algorithms and their application to antitachycardia devices are described below.

Algorithms↗

PubMedDate not supplied

Biosensors: clinical requirements and scientific promise.

Biosensors are currently very fashionable, even though they are not new! - an enzyme electrode being described almost 20 years ago by Updike and Hicks in 1967. The aim of this review is to put into perspective why biosensors are needed in clinical medicine and to describe some of the research that is being performed to develop such devices for, in particular, 'in vivo' applications.

Biotechnology↗

PubMed1992

[Development and application of biosensors for medical field].

Methods for the selective determination of organic compounds in biological fluids, such as blood, are very important in clinical analyses. Most analyses of organic compounds can be performed by spectrophotometric methods, based on specific enzyme-catalyzed reactions. However, because of the complicated procedure, these methods cannot be applied directly to bed-side monitoring. Alternatively, biosensors based on enzymes and electrochemical transducers possess excellent sensitivity for biological substrates and can determine a single compound in a biological fluid directly without need for a prior separation step. Therefore, in the past several years, many kinds of biosensors have been developed, and implantable microbiosensors for a body organ have also been reported.

Biomedical Engineering↗

PubMedDate not supplied

A cerebrospinal fluid glucose biosensor for diabetes mellitus.

A cerebrospinal fluid (CSF) glucose biosensor is introduced. The biosensor is a polarimeter that measures the rotation of plane polarized light proportional to glucose concentration. Preliminary in vitro studies revealed a linear response with good sensitivity over a range of glucose solutions (0-400 mg/dl). Anesthetized, adult dogs underwent intravenous glucose loading, and these preliminary in vivo studies resulted in good correlation (r = 0.98) between CSF polarimeter readings and CSF glucose by laboratory assay. This in vivo correlation suggests that both mutarotation of glucose anomer and changes from other optically active substances present in CSF are either negligible or constant over the range of glucose concentrations studied. The CSF polarimeter showed a significant rise soon after the intravenous loading of glucose (1-30 min) but a longer lag time (45-60 min) between the peak blood glucose and peak CSF polarimeter reading. This preliminary work extends, to the CSF, the concept of measuring optical rotation.

Animals↗

PubMed1992

[Biosensors and clinical analysis].

Method for the selective determination of organic compounds in biological fluids, such as blood, are very important in clinical analyses. Most analyses of organic compounds can be performed by spectrophotometric methods based on specific enzyme-catalyzed reactions. However, on account of the complicated procedure, these methods cannot be applied directly to bed-side monitoring. Alternatively, biosensors based on enzymes and electrochemical transducers possess excellent sensitivity for biological substrates and can determine directly a single compound in a biological fluid without need for a prior separation step. Therefore, in several years, many kinds of biosensors have been developed, and implantable microbiosensors for a body organ have also been reported. In the near future, an artificial pancreas fabricated by micromachine technology will be developed.

Biosensing Techniques↗