A Novel Conductometric Urea Biosensor with Improved Analytical Characteristic Based on Recombinant Urease Adsorbed on Nanoparticle of Silicalite

Development of a conductometric biosensor for the urea detection has been reported. It was created using a non-typical method of the recombinant urease immobilization via adsorption on nanoporous particles of silicalite. It should be noted that this biosensor has a number of advantages, such as simple and fast performance, the absence of toxic compounds during biosensor preparation, and high reproducibility (RSD = 5.1 %). The linear range of urea determination by using the biosensor was 0.05–15 mM, and a lower limit of urea detection was 20 μM. The bioselective element was found to be stable for 19 days. The characteristics of recombinant urease-based biomembranes, such as dependence of responses on the protein and ion concentrations, were investigated. It is shown that the developed biosensor can be successfully used for the urea analysis during renal dialysis

Development of a New Biosensor by Adsorption of Creatinine Deiminase on Monolayers of Micro- and Nanoscale Zeolites

This work is dedicated to the development of creatinine-sensitive biosensor consisting of pH-sensitive field-effect transistor (pH-FET) and creatinine deiminase (CD) immobilized with various types of zeolites, in particular, silicalite, zeolite beta (BEA) and nanobeta, and BEA zeolites, modified with gold nanoparticles and ions. For comparison, the traditional method of CD immobilization in saturated glutaraldehyde (GA) vapor was used. To modify pH-FET with zeolites, a monolayer method of deposition was applied. All basic analytical characteristics of the developed biosensors were compared: linear range of creatinine determination, time of response and regeneration, minimum limit of detection, and response reproducibility within a single biosensor; the calibration curves were plotted. It is shown that the use of zeolites of different types as adsorbents in the development of creatinine-sensitive biosensors resulted in a decrease of time of response and regeneration, an increase in sensitivity of the bioselective element to creatinine, and improvement in reproducibility of preparation of various biosensors, as compared with the method of covalent cross-linking in GA vapor