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