Urea is the final product of protein breakdown in the human body and plays an important role in clinical studies for early detection of chronic conditions. The concentration of urea in the urine of a healthy individual ranges from 110 to 390 mM. The aim of this project is to develop a biosensor that can rapidly monitor urea levels using a composite of urease immobilized on bovine serum albumin (BSA), safranin (SAF), and fullerene. The receptor element of the biosensor was created by modifying a graphite-paste working electrode with a nanomaterial suspension containing fullerene, a redox-active copolymer derived from BSA and SAF, and urease enzyme. This biosensor consists of a bionanocomposite-modified working electrode, a silver chloride reference electrode, and a potentiostat providing a constant potential of +0.275 V relative to the reference electrode. Analytical signals are generated by changes in current caused by urea addition to the cell. Urea is hydrolyzed by an enzyme, and the formed ammonia interacts with a SAF. When a potential is applied, the SAF transfers electrons to an electrode, leading to a change in the current. The pH of the buffer solution must be 6.8 for accurate measurements. The range of urea concentrations that can be determined using the developed electrode is between 68 and 410 mM. This test system can be used to monitor urea concentration in urine.

The research was supported by a grant from the Russian Science Foundation No. 23-73-01220, https://rscf.ru/project/23-73-01220/