ADAPTATION OF THE PROCEDURE OF CO-IMMOBILIZATION OF ENZYMES WITH DIFFERENT MODIFICATIONS OF ZEOLITES ON THE SURFACE OF CONDUCTOMETRIC TRANSDUCERS

A comparative study of different parameters of conductometric biosensors based on urease and glucose oxidase, co-immobilized with different types of zeolites. Urease immobilized on silicalite-2 was shown to have better performance than immobilized urease without zeolites. Conductometric biosensor with glucose oxidase co-immobilized with zeolite NH4+-Beta 25 had similar response values compared to immobilized enzyme without zeolite. Immobilization of zeolites NH4+-BEA 30 and H+-BEA 30 together with urease leads to an increase in the response of the biosensor, while the reproducibility of the signal remains unchanged. Biosensors with zeolites with a higher Si/Al ratio were characterized by increased signals. The use of zeolites modified with methylviologen and silver did not give a positive effect.

DEVELOPMENT OF ARGININE DEIMINASE BASED CONDUCTOMETRIC BIOSENSOR FOR ARGININE DETERMINATION

For the first time, a conductometric enzyme biosensor was developed to determine arginine concentrations. The bioselective membrane of the biosensor was formed by immobilization of arginine deiminase on the surface of gold planar transducer using covalent crosslinking of glutaraldehyde with bovine serum albumin. An effect of the solution characteristics (ionic strength, buffer capacity) on the biosensor functioning was studied. The proposed monoenzyme biosensor was shown to have high sensitivity to arginine (minimum limit of detection - 5 μM) and good selectivity towards possible interferents. The linear range of determination was from 10 to 800 μM. The biosensor sensitivity to arginine is 72 μS /μM. The developed biosensor was demonstrated to be promising for the arginine analysis in real samples.

THE DEVELOPMENT OF CONDUCTOMETRIC BIOSENSOR FOR DETERMINATION OF URIC ACID CONCENTRATION IN HUMAN SERUM USING SCREEN PRINTED CARBON ELECTRODE (SPCE) – NATA DE COCO

The control of uric acid is important. A high level of uric acid can cause gout disease. Therefore a simple, fast, and accurate method for uric acid determination is required. In this research a conductometric biosensor has been developed by SPCE – Nata de coco for uric acid determination. The prepared biosensor was optimized to get a good performance of biosensor and it is applicable for human serum samples. The optimized variables were enzyme concentration, membrane thickness and pH solution. The various enzyme concentration were 6 μg/mL; 12 μg/mL; 18μg/mL; 24 μg/mL. The various membrane thickness were 5 μm; 10 μm; 15 μm. Meanwhile, the various pH solution were 7; 7.5; 8; 8.5; 9. The optimum enzime concentration was 18 µg/mL with the membrane thickness and pH were 5 µm and 8, respectively. The prepared biosensor can determine the uric acid concentration at range of 0 – 1.2 ppm with the sensitivity of 7.74 µS/ppm and the limit detection is 0 ppm. The biosensor was applied to uric acid detection in human serum with accuracy of 95 %.

THE DEVELOPMENT OF CONDUCTOMETRIC BIOSENSOR FOR DETERMINATION OF URIC ACID CONCENTRATION IN HUMAN SERUM USING SCREEN PRINTED CARBON ELECTRODE (SPCE) – NATA DE COCO

The control of uric acid is important. A high level of uric acid can cause gout disease. Therefore a simple, fast, and accurate method for uric acid determination is required. In this research a conductometric biosensor has been developed by SPCE – Nata de coco for uric acid determination. The prepared biosensor was optimized to get a good performance of biosensor and it is applicable for human serum samples. The optimized variables were enzyme concentration, membrane thickness and pH solution. The various enzyme concentration were 6 μg/mL; 12 μg/mL; 18μg/mL; 24 μg/mL. The various membrane thickness were 5 μm; 10 μm; 15 μm. Meanwhile, the various pH solution were 7; 7.5; 8; 8.5; 9. The optimum enzime concentration was 18 µg/mL with the membrane thickness and pH were 5 µm and 8, respectively. The prepared biosensor can determine the uric acid concentration at range of 0 – 1.2 ppm with the sensitivity of 7.74 µS/ppm and the limit detection is 0 ppm. The biosensor was applied to uric acid detection in human serum with accuracy of 95 %.