Biomedical subjects

S V Dzyadevich

Publications and source records attributed to S V Dzyadevich.

3 recordsLinked to original sources

PubMed1999

Application of enzyme field-effect transistors for determination of glucose concentrations in blood serum.

Glucose-sensitive enzyme field effect transistors (ENFETs) modified by an additional Nafion membrane have been developed and used for diluted blood samples analysis. The ENFET was used in the linear portion of the calibration curve up to 1.5 mM glucose in a model solution, which corresponds with up to 60 mM glucose in the undiluted samples (dilution 1:40). The high linearity of the Grans curve (factor of linearity is 1.03) obtained by the method of standard additions indicates the high precision of analysis. Glucose concentrations in different blood serum samples determined by ENFETs were compared with those measured by the commercial analyzer 'Eksan-G' and colorimetric method ('Diagluc' enzymatic kit), and good correlation between these methods was revealed. The high reproducibility and operational stability of the biosensor developed were demonstrated.

Animals↗

PubMed1994

Thin-film conductometric biosensors for glucose and urea determination.

The characteristics of the developed conductometric biosensors for urea and glucose determination are described. Conductometric transducers based on thin-film interdigitated metal (Au, Cr, Cu, Ni) electrodes were studied, and enzymes urease and glucose oxidase were used for the selective membranes formation on the chips having gold electrodes. The influence of ionic strength and buffer capacity of the samples on the biosensors response in kinetic and steady-state modes of measurements was thoroughly tested. It was shown that the kinetic response of the sensors does not depend on the buffer capacity of the analyzed sample. In basic features the performance of the developed biosensors is rather close to that of respective enzyme field effect transistor, though the former are much superior when the technological complexity of the transducer itself is considered and taking into account that conductometric sensors require no reference electrode.

Biosensing Techniques↗

PubMedDate not supplied

Conductometric biosensor for ethanol detection based on whole yeast cells.

The quantification of ethanol in alcoholic beverages was performed by yeast cell-based conductometric biosensor. A membrane with yeast cells immobilized in 2% Ca-alginate gel was attached on gold planar electrodes. Changes in conductivity due to the specific consumption of ethanol by yeast cells were registered by the computer-controlled sensor system. The response time of the constructed microbial sensor was less than 5 min, linearity (in a logarithmic scale) was observed in the range of 5-100 mM alcohol concentration. It was established that pH value in their region from 5 to 8 did not influence the levels of initial signal. The increase of a buffer capacity in the sample results in the decrease of the biosensor output. The minimal detectable level of ethanol was 1 mM and the relative standard deviation appeared to be 10-12% for 15 repeated assays. When the system was operated and stored at 20-25 degrees C, the biosensor response was stable for only 3 days. However, when the microbial sensor was stored at 4 degrees C, the system was stable up to 12 days. Good correlation between the results obtained by a conductometric cell-biosensor and gas chromatograph was observed.

Alcoholic Beverages↗