Biomedical subjects

F Lisdat

Publications and source records attributed to F Lisdat.

5 recordsLinked to original sources

PubMed2001

Research and development in biosensors.

Progress in biosensors has mainly been made by the improvement of the biological components and the implementation of microsystem technologies. Enzymes are still the most appropriate recognition elements because they combine high chemical specificity and inherent biocatalytic signal amplification. A breakthrough has been achieved in the application of membrane-integrated receptor systems for analyte recognition and signal transduction in biosensors. Sensor integration of RNA aptamers has been initiated, and the performance of fully synthetic molecularly imprinted polymers has been improved.

Antibodies↗

PubMed2000

Electrochemical investigation of cellobiose oxidation by cellobiose dehydrogenase in the presence of cytochrome c as mediator.

An important aspect of the cytochrome c electrochemistry is the possibility of coupling the 'heterogeneous reactions' with other redox enzymes. Cellobiose dehydrogenase, a 89170 Da glycoprotein that contains both FAD and a b-type haem as prosthetic groups, donates electrons to a number of acceptors, including cytochrome c. While haem b is surrounded mainly by acidic amino acids, cytochrome c displays positive charged lysine groups around the haem site. Thus a fast reaction between both proteins is explicable. In the presence of cellobiose, a catalytic current was observed, owing to the interaction of cellobiose dehydrogenase with electrostatically adsorbed cytochrome c. Adsorption of cytochrome c provides a technological model surface for vectorial electron transfer.

Carbohydrate Dehydrogenases↗

PubMed1997

Catecholamine detection using enzymatic amplification.

Different amplification sensors based on the substrate recycling principle were investigated with respect to their applicability to catecholamine detection. In the bioelectrocatalytic approach, glassy carbon electrodes were modified by laccase or a PQQ-dependent glucose dehydrogenase. Substrate recycling occurs and the detection limit is in the lower nanomolar concentration range (e.g. 10 nM dopamine and 1 nM noradrenaline for the laccase- and glucose dehydrogenase-modified electrodes, respectively). Combinations of glucose dehydrogenase with laccase or tyrosinase were investigated as bienzymatic probes. Among the systems we studied, the laccase/glucose dehydrogenase sensor is the most sensitive (detection limit: 0.5 nM adrenaline). The selectivities of the different sensor systems are discussed. Application of the laccase/glucose dehydrogenase electrode in different media (i.e. brain homogenate, heart effluate) was successfully shown. For samples with high concentrations of interfering substances (uric and ascorbic acid), the interferences can be effectively removed using enzymatic methods.

Biosensing Techniques↗

PubMed1997

Enzymatic substrate recycling electrodes.

A weak chemical signal might result in a large response when biochemically amplified. Enzymatic recycling of the analyte is one of the biochemical ways of providing an effective increase in biosensor sensitivity by several orders of magnitude. The enhancement of sensitivity is provided by consecutive consumption and generation of the analyte on the sensor surface. The principle of enzymatic substrate regeneration using bioelectrocatalysis and coupled enzymes is shortly reviewed and illustrated with some recent developments of biosensors for catecholamines, and its potential for electrochemical immunoassays is outlined.

Biosensing Techniques↗

PubMed1997

Ultrasensitive bienzyme sensor for adrenaline.

A biosensor consisting of an analyte-recycling two-enzyme system using laccase (Coriolus hirsutus) and PQQ-dependent glucose dehydrogenase in combination with the electrochemical detection of oxygen depletion at a platinum electrode was used for adrenaline determination in the nano- and subnanomolar concentration range. Measurements were performed in a flow cell providing excellent baseline stability and fast recovery of the sensor. Improved design of the polymer matrix resulted in a lower detection limit of 200 pmol/l for adrenaline. The sensor has successfully been applied to the analysis of adrenaline in effluate of isolated rabbit hearts.

Animals↗