Use of biocompatible redox-active polymers based on carbon nanotubes and modified organic matrices for development of a highly sensitive BOD biosensor.

This work investigated the use of redox-active polymers based on bovine serum albumin and chitosan, covalently bound to mediators neutral red and ferrocene and containing carbon nanotubes, for immobilization of Paracoccus yeei VKM B-3302 bacteria. The structures of produced polymers were studied by IR spectroscopy and scanning electron microscopy. Cyclic voltammetry and impedance spectroscopy found the electrochemical characteristics of the investigated systems: the heterogeneous electron transfer rate constant, the constant of the rate of interaction with P. yeei bacteria and the impedance. The systems containing carbon nanotubes and ferrocene-based redox-active polymer proved to be the most promising. Biosensors formed using the hybrid polymers had a high sensitivity with the lower boundary of 0.1 mg/dm3 of the detected BOD5 concentrations and a high correlation (R = 0.9916) with the standard BOD assay of surface water samples.

A mediator microbial biosensor for assaying general toxicity.

A mediator biosensor based on Paracoccus yeei bacteria for assaying the toxicity of perfumery and cosmetics samples was developed. An approach to selecting an electron-transport mediator based on the heterogeneous electron transfer constants for investigated mediators (ks) and the mediator-biomaterial interaction constants (kinteract) was proposed. Screening of nine compounds as potential mediators showed a ferrocene mediator immobilized in graphite paste to have the highest efficiency of electron transfer to the graphite-paste electrode (the heterogeneous transfer constant, 0.4 ±â€¯0.1 cm/s) and a high constant of interaction with P. yeei (0.023 ±â€¯0.001 dm3/(g·s)). A biosensor for toxicity assessment based on the ferrocene mediator and P. yeei bacteria was formed. The biosensor was tested on samples of four heavy metals (Cu2+, Zn2+, Pb2+, Cd2+) and two phenols (phenol and p-nitrophenol). Proceeding from the EC50 index, it was found that the use of the ferrocene mediator made the biosensor more sensitive to investigated toxicants than most analogues described. Toxicity determination of four perfumery and cosmetics samples by the developed biosensor showed prospects of using this system for real-time toxicity monitoring of samples.

Glucose biosensor based on screen-printed electrode modified with silicone sol-gel conducting matrix containing carbon nanotubes.

This research shows that high-performance biosensors can be produced by modification of screen-printed electrodes with enzymes and conducting hydrogel based on sol-gel matrix and single-walled carbon nanotubes. Tetraethoxysilane, dimethyldiethoxysilane and polyvinyl alcohol were used as the sol-gel matrix basis. Modified SWCNT provide direct electron transfer during glucose oxidation, as confirmed by cyclic voltammetry. The developed conducting sol-gel screen-printed electrodes can determine glucose within the concentration range 0.045-1.04 mM. The developed biosensor is not only in pace with its world analogues but even exceeds them by some analytical and metrological properties. The developed conducting sol-gel biosensor was used to measure the concentration of glucose in blood. The test results differed only insignificantly from those received with the help of standard glucose meter.