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At least 811 records · Page 45Linked to original sources

PubMed2000

Application of a channel biosensor for toxicity measurements in cultured Alexandrium tamarense.

The purpose of this study is to examine the toxicity of Alexandrium tamarense strains using a channel biosensor. With this biosensor, we were able to measure very small quantities of PSP toxin contained within an individual plankton cell. However, measurement of at least 100 cells is more desirable for increasing the sensitivity of the assay. Therefore, in the near future, the proposed biosensor system may be used for monitoring the STX (saxitoxin) produced by a few naturally toxic phytoplankton, and also measuring small amounts of toxin in shellfish.

Biological Assay↗

PubMed2000

Binding measurements as surrogate biological assays: surface plasmon resonance biosensors for characterizing vaccine components.

There is considerable interest in the possibility of using surrogate physico-chemical assays for the quality control of vaccine components. Since biological activity always depends on a first binding step, the primary criterion for assessing biological activity is the ability of a vaccine component to bind specifically in a binding assay. Biosensor instruments that measure binding kinetics with considerable ease and precision are used increasingly to assess the quality of antigens intended for vaccination as well as the binding affinity of antibodies elicited by vaccination. The most widely used biosensor instrument is the BIACORE and its mode of operation is briefly described. The use of biosensors for measuring the active concentration of biomolecules and for assessing the probable effectiveness of vaccine-induced antibodies is described.

Biological Assay↗

PubMed2001

Electrochemical biosensors for evaluation of contaminants in food.

This paper describes the application of electrochemical disposable biosensors in food analysis, which have recently been developed in our laboratory. Disposable biosensors, based on acetylcholinesterase inhibition activity, were exploited for testing the presence of organophosphorus and carbamate pesticides in water, fruit, and vegetable samples. The paper further describes preliminary tests for the detection of genetically modified organisms and hybridisation by coupling the DNA biosensors with the polymerase chain reaction.

Biosensing Techniques↗

PubMed2001

Toxicity testing in environmental monitoring: the role of enzymatic biosensors.

Biological toxicity testing is a rapidly expanding field involving numerous bioanalytical techniques. The enzymatic biosensors are valuable screening tools to identify pollutants and/or toxic agents in the environment and/or in food matrices, thus representing a valid alternative to animal testing in analytical toxicology. Inhibition based biosensors here presented have been proved to represent alternative assays for the toxicity evaluation of warfare agents and endocrine disrupting chemicals as well as algal toxins (phycotoxins) in the contamined sea foods (mainly clams and other mollusks). Results obtained by inhibition studies performed by means of several enzymatic biosensors indicate the reliability of the proposed method and the possibility to extend such an experimental approach to other toxicants as a simple, rapid and cheap biotest, to be used easily also "on the spot".

Animals↗

PubMed2002

Application of recombinant fluorescent mammalian cells as a toxicity biosensor.

With respect to developing a more sensitive biosensor, a recombinant fluorescent Chinese Hamster Ovary cell line was used for the monitoring of various toxicants. Both cell lines, EFC-500 and KFC-A10, were able to detect toxicants sensitively. They were characterized with mitomycin C and gamma-ray as genotoxicants and bisphenol A, nonylphenol, ziram and methyl bromide as possible and known EDCs. When compared to each other, the response of KFC-A10 was generally more informative and sensitive. Compared to typical bacterial biosensor systems, these cell lines offered a sensitivity of 2- to 50-fold greater for the tested chemicals. Based on these results, the use of mammalian cells offers a sensitive biosensor system that is not only fast, cheap and reproducible but also capable of monitoring the endocrine-like characteristics of environmental toxicants.

Animals↗

PubMed1996

The Study of a New Type of Membrane for Biosensor.

Polyvinyl alcohol (PVA) was selected to develop a new type of membrane for biosensor. The PVA membrane was first activated by cyanogens bromide, followed by coupling with ethyl diamine. After treated by glutaraldehyde, glucose oxidase and lactate oxidase were immobilized onto the membrane respectively. Coupled with oxygen electrode, the enzyme membrane was used to construct glucose and lactate biosensor respectively. The linear range was 5 mg/dl-800 mg/dl for glucose and 1mg/dl-35 mg/dl for lactate, and the response time of these biosensors was 10 seconds.

Journal Article↗

PubMed2002

Toxicity assessment of 255 chemicals to pure cultured nitrifying bacteria using biosensor.

The bioassay has been attracting attention as a method of toxicity assessments of micropollutants in the environment. In this study, we report the characteristics (selectivity and sensitivity) of the nitrifying bacteria biosensor for 255 kinds of chemicals as a model of chemical contaminant in the environment and the results of evaluation of mixed samples of several substances. In the nitrifying bacteria respiration inhibition test using the biosensor, 56 chemicals were detected. It was found that this biosensor is especially sensitive to seven chemicals that have a thiocarbonyl functional group (>C=S), such as a thioamide group of thiocarbamate group. These chemicals are considered to specifically inhibit AMO by chelation of copper. The samples consisted of a mixture of seven types of anilines that inhibit respiration in the bacteria, a mixture of five types of chlorophenols, and a mixture of eight types of substances that contain thiocarbonyl groups were examined. All of the mixed samples inhibited the respiration of the nitrifying bacteria more than 10% by the inhibition rate, and observed a synergistic effects of the substances in the samples.

Aniline Compounds↗

PubMed2003

[Development of a new biosensor for biochemical oxygen demand].

OBJECTIVE: To use a new kind of fixing material, i.e. Sol-Gel organic-inorganic hybridized material to immobilize bacterium to detect Biochemical oxygen demand quickly. METHODS: The biosensor was fabricated using a thin film in which Hansenula anomala was immobilized by sol-gel and an oxygen electrode. The optimum measurement for biochemical oxygen demand was at pH 7.0; 28 degrees C; response time 3 - 12 min. Pure organic compound, sewage and rate of recovery were detected with the biosensor. RESULTS: It shows that the BOD biosensor can be used to detect many organic compounds such as amino acid, glucide. It is suitable to monitor sewage and industrial waste water which has low level alcohols and phenols. The microbial membrane can work 3 months and remain its 70% activity. It is measured that the rate of recovery of BOD is between 90% to 105% in sewage. CONCLUSION: The study confirmed the effectiveness and usefulness of BOD sensor, which is quick, convenient, low cost and reliable with little interference.

Bacteria↗

PubMed1992

Microdialysis and glucose biosensor for in vivo monitoring.

Microdialysis coupled to a glucose biosensor led to a continuous monitor system in vivo for glucose. Several microdialysis probes were used to stabilize the biosensor response. In vivo experiments, especially when the probe was placed subcutaneously, showed that the sensitivity of the biosensor decreased continuously; various kinds of fibers with a molecular weight cut-off (MWCO) ranging from 6,000 to 20,000 were compared. A wall-jet flow cell as detector for glucose showed less interference when compared to a thin layer cell. Glucoday, a new commercial instrument based on this principle, is presented.

Biosensing Techniques↗

PubMedDate not supplied

[Electrochemical reduction of cytochrome P450 as a way for construction of biosensors and bioreactors].

The present review describes the data on electrochemical reduction of cytochrome P450. Three generations of enzyme biosensors have been considered. The concept and potentialities of enzyme electrodes--transducers--as the main element on construction of electrochemical biosensors are described. Different types of electrodes for bioelectrochemistry are presented. New experimental approaches for immobilisation of cytochrome P450 based on nanotechnology are reported. Nanobiotechnology in electrochemistry has potential application for production of biosensors and bioreactors for medicine

Bioreactors↗

PubMedDate not supplied

Applications of array biosensor for detection of food allergens.

Although food is a necessity, compounds within food products can be dangerous and life-threatening for people with food allergies. These allergy-causing compounds, such as proteins from eggs and milk, must be identified on the labels of commercial products. Unintentional contamination of food with these compounds occurs as a result of storage, manufacturing procedures, or cleaning procedures. A sensitive, specific, and rapid method to identify foods containing allergens is required by the food industry. The array biosensor, a rapid detection system, may provide a solution to this need. The array biosensor performs fluorescent immunoassays on the surface of a planar waveguide by first running samples, then fluorescently labeled antibodies, over a surface patterned with capture antibodies. An optical image is captured by a charged-coupled device camera and converted into fluorescence values. Signal intensity and spot location provide information on the compound and its concentration. The array biosensor has been successfully demonstrated for toxin, bacteria, and virus detection at low levels in under 20 min in food, clinical samples, and environmental matrixes. An assay for detection of ovalbumin as an indicator of egg contamination has been developed with limits of detection of 25 pg/mL in buffer and 1.3 ng/mL (13 ng/g) in non-egg pasta extract (buffer:pasta 10:1, v/w).

Allergens↗

PubMedDate not supplied

[Microbial, enzymatic, and immune biosensors for ecological monitoring and control of biotechnological processes].

Results of the research performed at the Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, on designing immunobiosensors for detection of toxic compounds and microbial cells enzyme-based biosensors for detection of hydrocarbons and alcohols, and microbial biosensors for aromatic compounds, surfactants, and biological oxygen consumption are briefed. Parameters of the mediator electrodes involving microbial cells and data on the properties of microbial biofuel cells--devices based on biosensor principle and representing alternative sources of electric energy--are given.

Alcohols↗

PubMedDate not supplied

Biosensor analysis of beta-lactams in milk using the carboxypeptidase activity of a bacterial penicillin binding protein.

The applicability of a beta-lactam receptor protein for detection of beta-lactam antibiotics in milk using surface plasmon resonance (SPR) biosensor technology was investigated. The advantage of using a receptor protein instead of antibodies for detection of beta-lactams is that a generic assay, specific for the active form of the beta-lactam structure, is obtained. Two assays based on the enzymatic activity of the DD-carboxypeptidase from Actinomadura R39 were developed, using a Biacore SPR biosensor. The carboxypeptidase converts a tri-peptide into a di-peptide, a reaction which is inhibited in the presence of beta-lactams. Polyclonal antibodies against the 2 peptides were developed and used to measure the amount of enzymatic product formed (di-peptide assay) or the amount of remaining enzymatic substrate (tri-peptide assay), respectively. The 2 assays showed similar performances with respect to detection limits (1.2 and 1.5 microg/kg, respectively) and precision (coefficient of variation <5%) for penicillin G in milk. Several other beta-lactams were detected at or near their respective maximum residue limit. Furthermore, the 2 peptide assays were evaluated against 5 commercial kit tests in the screening of 195 producer milk samples. The biosensor assays showed 0% false-negative and 27% false-positive results, whereas the figures were 0% false-negative and 27-53% false-positive results for other screening tests investigated.

Animals↗

PubMedDate not supplied

Food allergen detection with biosensor immunoassays.

An optical biosensor was used to develop both direct and sandwich immunoassays for the detection of proteins from milk, egg, hazelnut, peanut, shellfish, and sesame in food samples. Affinity-purified polyclonal antibodies raised against the proteins were immobilized on the biosensor chip. Food samples were injected and the proteins that bound to the antibodies on the surface were detected by a shift in the resonance angle. By adding a second antibody in a sandwich assay, matrix effects could be overcome and the sensitivity and selectivity enhanced. Detection of allergen levels down to 1-12.5 microg/g in food samples was demonstrated for the various assays. Good agreement of results was also obtained from parallel analysis with alternative immunoassays, including rocket immunoelectrophoresis, enzyme immunoassay, and immunoblotting. The present study demonstrates that the sensitivity of the described biosensor technique is comparable to the most sensitive enzymed-linked immunosorbent assays.

Allergens↗

PubMedDate not supplied

Biosensor screening for veterinary drug residues in foodstuffs.

The advent of the surface plasmon resonance (SPR) biosensor has led to many applications in diverse fields from the pharmaceutical industry to the life sciences and other areas within biotechnology. One area that has seen a significant increase in applications is the testing for veterinary drug residues in foodstuffs. These include tests for antibiotics, beta-agonists, and antiparasitic drugs. The introduction of the Biacore Q in the late 1990s, an SPR biosensor dedicated to the food industry, and the complementary development of kits to test for these residues mean that end users have a viable alternative screening test to the established enzyme-linked immunosorbent assay (ELISA) techniques. This paper reviews many SPR biosensor veterinary drug tests that have been developed, with particular emphasis placed on kit-based assays.

Anti-Bacterial Agents↗

PubMed1991

[Biosensors for the determination of phenol and benzoate on the basis of Rhodococcus cells and enzyme extracts].

An amperometric biosensor for determination of phenol, cresol, benzoate and 2-methyl-4-chlorophenol using Rhodococcus-cells and enzyme extracts of Rhodococcus has been developed. The influence of cultivation of Rhodococcus-cells and preincubation of the biosensor with desired substrate on sensibility and specificity was been investigated. In relation to cultivation and preincubation the Rhodococcus sensor was high specific to benzoate or phenol and cresol. A linear range was obtained for phenol and benzoate up to 80 mumol and for 2-methyl-4-chlorophenol up to 400 mumol. The biosensor using enzyme extracts show a higher specificity, it is but necessary NADPH. A further disadvantage is the little measuring range of this sensor.

Benzoates↗

PubMedDate not supplied

[Nucleic acids as a basis for creating biosensors].

Here we present a brief conception of biosensors. Structural peculiarities and properties of single- and double-stranded nucleic acids that are to be taken into account when creating biosensors on the basis of these biomolecules are considered. On the example of two biologically active compounds a possibility is shown for constructing biosensors on the basis of liquid-crystalline dispersions of low molecular mass DNA and on the basis of liquid-crystalline DNA dispersions immobilized due to their inclusion into the synthetic polymeric matrix.

Biosensing Techniques↗

PubMed1994

Use of biosensors to characterize recombinant proteins.

A new biosensor technology based on surface plasmon resonance (BIAcore, Pharmacia) is described which allows the surface and conformational integrity of a recombinant product to be monitored by measuring the binding characteristics of a panel of monoclonal antibodies. Interactions between the antibodies and the recombinant product are measured in real time in a quantitative and highly reproducible manner. This allows the association and dissociation kinetic rate constants of the antibodies to be calculated and not only the equilibrium binding constant. Besides using antibodies as conformational probes, the biosensor can also be used to measure directly the binding of a recombinant product to its natural biological ligand. Quantitative binding assays using biosensors are a powerful method for assessing the lot-to-lot consistency of recombinant products.

Amino Acid Sequence↗