SYNTHESIS OF CONDUCTING BIOPOLYMER BASED BIOSENSOR FOR POLLUTANTS DETECTION IN ENVIRONMENTAL MONITORING

Abstract

The increasing concentration of heavy metals in the water systems has been a major concern these days. A number of diseases have been reported, which is due to the bioaccumulation of these toxic elements in the human body. This thesis proposes a biocompatible, non-toxic method for the identification of these metal ions from the polluted aquatic samples. A conductometric urease biosensor, having Katira-cl-AAc/PANI hydrogel composite as the bio-sensing platform has been fabricated on the ITO electrode. The utilization of the natural polysaccharide, katira gum, has resulted in an enhanced conductivity along with the incorporation of the conducting polymer – polyaniline. Hydrogel provides greater surface area for the enzyme to react with the substrate, which has been used for the construction of the immobilization matrix. The hydrolysis of urea into carbon dioxide and ammonia are catalysed by the enzyme urease. The metallic inhibitors of urease are quantified in this work, using different electrochemical techniques. A comparative study of different concentrations of three heavy metal ions, cadmium, cobalt and mercury, has been done. The fabricated enzyme electrode, Urease/Katira-cl-AAc/PANI/ITO, exhibits greater stability, enhanced sensitivity and a wide range of detection limit (200 to 270 ng L-1) with a shelf life of 28 days for both substrate and inhibitors.