On the Development of Reagent-free Conductive Nanocomposite Systems for the Modification of Printed Electrodes When Producing Glucose Biosensors

The possibility of using redox-active polymers based on bovine serum albumin (BSA) and chitosan covalently linked to neutral red, thionine, and ferrocene mediators, and containing carbon nanotubes (CNTs) for glucose-oxidase immobilization is investigated. The structure of the obtained polymers is studied by infrared (IR) spectroscopy, spectrophotometry, atomic-absorption spectroscopy, and scanning electron microscopy. Using the method of cyclic voltammetry, the electrochemical characteristics of the studied conductive nanocomposite systems are found, namely, a heterogeneous rate constant of electron transfer and a rate constant of interaction with glucose oxidase. The systems containing a redox-active polymer based on BSA modified with a ferrocene mediator turn out to be the most promising. Biosensors formed using nanocomposite matrices have a high sensitivity with a lower limit of determined glucose concentrations of 0.1 mM and are characterized by a high correlation ( R 2 = 0.9827) with the results of determining the glucose content in human blood by the standard method.