Development of manganese peroxidase based voltammetric biosensor for detection of textile Azo dyes RR 195 & RB 221

Abstract

Azo dyes are extensively applied in textile and leather industries. Monitoring the toxicity and rate of exhaustion of such pollutants besides their mineralization are extremely important for environmental safety and sustainability. Detection of dyes based on enzyme inhibition mechanism and exploration of effect of various dyes on enzymes such as manganese peroxidase (MnP) for such purpose are not studied previously. The goal of the study is to develop MnP based biosensor and to determine whether all dyes impart inhibitory effect on enzyme or not. Thereby, two different dyes i.e. Reactive Red 195 (RR195) and Reactive Blue 221 (RB221) were used for the study and purified MnP was co-immobilized on carbon felt electrode for quantitative measurement of these dyes using electrochemical signals. Voltammetric analysis was carried out to determine the effects of different dye concentrations on the enzyme activity in the form electric signal (I) at an applied voltage of −1 to +1. It was revealed that increase in concentrations(10 μg/L −50 mg/L) of RR195 and RB221 transfuse inhibitory and non-inhibitory effect on MnP activity resulting in current (I) output reduction and enhancement respectively. To validate the study, another study was also conducted, which investigated the effect of these dyes on fungal growth and manganese peroxidase enzyme activity in-vitro. The results obtained authenticated the biosensing results obtained by CV as RR195 inhibit MnP activity (highly toxic) and RB221 impart no effect on MnP activity (less toxic). The fabricated biosensors demonstrated reproducibility, durability, and low threshold of detection with little interference from other substances. Even 100 days later, the MnP-based biosensors showed minor fluctuation in its current (I) outputs with 96–36 % and 86-65 % stability in case of RR195 and RB221 respectively. The study demonstrated the application of enzyme-based biosensors for both detection and toxicological monitoring of dyes.