Topolnikova Y. Development of biosensor system for simultaneous determination of lactate and pyruvate concentration in biological fluids for clinical diagnostics.

The thesis is devoted to the development of a biosensor system for the determination of concentrations of lactate and pyruvate and their ratio in blood serum for use in clinical diagnosis. The lactate- and pyruvate-sensitive monobiosensors and the biosensor system for simultaneous determination of lactate and pyruvate were created, their working laboratory prototypes were elaborated. The method of enzymes immobilization was optimized, as well as a composition of the working buffer solution. The key analytical characteristics of the biosensor system were investigated. The effect of parameters of a buffer solution (pH, ionic strength, buffer capacity) on the work of the biosensor system was studied. The response reproducibility and operational stability were evaluated along with the stability during storage. It was shown that there was no cross-influence of the substrates and cofactors of monobiosensors at their simultaneous operation as the parts of a single system. The developed biosensor system was tested as a component of the multibiosensor for monitoring lactate, pyruvate, glucose, glutamate, choline and acetylcholine. The developed system was used for measurement of lactate and pyruvate concentrations in real samples of blood serum. It is shown a high correlation of the obtained data with the results of control spectrophotometric method. The obtained laboratory prototype of the biosensor system can be used as a basis for elaboration of commercial devices for clinical diagnosis. Keywords: biosensor system, lactate, pyruvate, amperometric transducer, biosensor, diagnosis of lactic acidosis, medical diagnostics.