[Biosensors for assay of glycoalkaloids in potato tubers].

The possibility of commercial application of biosensors based on pH-sensitive field-effect transistors and butyrylcholinesterase to glycoalkaloid analysis in potato tubers was studied. The main analytical features of the designed biosensors and measurement conditions were optimized. The biosensor was applied to quantitative analysis of glycoalkaloids in tubers of different potato varieties. The results proved to be in good agreement with those obtained by conventional protocols. Experiments on glucose assay were performed. An inverse correlation between the contents of glucose and glycoalkaloids in potato tubers was demonstrated.

[Adaptation of amperometric enzyme biosensor for glucose analysis in wine]. / Adaptatsiia amperometricheskogo fermentnogo biosensora dlia analiza gliukozy v vinakh

The amperometric enzyme biosensor was used for glucose analysis in grape wine. To decrease the influence of the samples under analysis on analytical characteristics of the biosensor the additional nafion membrane was deposited on the enzyme membrane. The sensor work was investigated in different conditions. It was shown that application of additional membrane did not change effectively main analytical characteristics of the biosensor. Biosensors with and without additional membrane are characterized by similar linear dependence on glucose concentration (0-8 mM) and on minimal detection limit of glucose (30 microM). Experiments for detection of glucose concentration in wine by means of the biosensor with additional negative charge membrane were conducted. A good correlation between data obtained by the biosensor method and presented by producers was shown.

[Development of enzyme biosensor based on trypsin and conductometric thin-film electrodes for protein and artificial substrates determination]. / Enzimosensor na osnovi tripsinu ta konduktometrichnykh planarnykh elektrodiv dlia viznacheniia vmistu bilkiv peptidnikh substrativ u vodnikh rozchinakh

Two analytical systems based on the soluble and immobilized trypsin and conductometric thin-film electrodes were developed to measure concentration of artificial substrate and protein in solution. It was shown that these systems allow one to determine concentrations of Ha-benzoyl-L-arginin-ethyl-ester in the range of 0.1-1.0 mM and concentrations of HSA: 0.1-2.0 mg/ml with soluble and 0.1-0.8 mg/ml with immobilized trypsin.

[Enzyme biosensors for penicillin determination based on conductometric planar electrodes and pH-sensitive field effect transistor]. / Fermentnye biosensory dlia opredeleniia penitsillina na osnove konduktometricheskikh planarnykh élektrodov i pH-chuvstvitel'nykh polevykh tranzistorov.

The enzyme biosensors for penicillin determination based on conductometric planar electrodes and pH-sensitive field effect transistors have been described and their working parameters have been compared. The influence of pH, buffer capacity and ionic strength of the samples on the biosensors response has been studied. Short response time and high operational stability are characteristics of the developed biosensors.

[Amperometric enzyme biosensor with a glucose oxidase-polyaniline membrane]. / Amperometricheskii fermentnyi biosensor s membranoi gliukozooksidaza-polianilin.

An amperometric glucose biosensor was made by electrochemical polymerization of aniline onto the gold electrodes in presence of the enzyme glucose oxidase in the phosphate buffer solution with pH 7.0. Aniline is easily polymerized forming a thin film, which adheres tightly on the electrodes surface. During the electropolymerization process glucose oxidase was entrapped into polyaniline film which then became the catalyst of the enzyme reaction of glucose hydrolysis. Experiments were performed to determine optimal conditions of polyaniline-glucose oxidase film preparation. Glucose was amperometrically determined with the electrochemically fabricated biosensor in the concentration range 10(-4) M to 2 x 10(-2) M. The linearity of the enzyme electrode response ranged from 2 x 10(-4) M to 6 x 10(-3) M. The electrochemical synthesis of a polyaniline-enzyme thin film a high-technologic one and this permits fabricating various microbiosensors and multisensors in the continuous technological cycle.

[Use of conductometric microsensors for studying kinetic parameters of enzymes]. / Ispol'zovanie konduktometricheskikh mikrosensorov dlia izucheniia kineticheskikh parametrov fermentov.

An alternative method based on thin-film conductometric microsensor is suggested for studying enzyme kinetics. It is established that the immobilized enzyme as well as soluble one is described by the classic lows of enzyme kinetics. Major parameters (Km and Vmax) are identical to those measured by the widely used methods and their amounts are 1.33 mM and 9.04 microS/min for soluble urease and 3.73 mM and 13.8 microS/min for immobilized urease; 5.26 mM and 13.9 microS/min for immobilized glucose oxidase; 13.6 mM and 122.0 microS/min for immobilized acetyl cholinesterase; 10.8 mM and 129.9 microS/min for immobilized butyryl cholinesterase. The possibility of conductometric analyzer application for detection of toxin concentration, in particular pesticides, is shown. Advantages and disadvantages of the system suggested are discussed.