A novel integrated biosensor based on co-immobilizing the mediator and microorganism for water biotoxicity assay

A novel integrated biosensor for biotoxicity assay has been developed by co-immobilizing microorganisms and mediators within a novel redox hydrogel. The proposed redox hydrogel acts as an immobilizing matrix both for microorganism E. coli and redox mediator, which was prepared by grafting the benzoquinone (BQ) redox mediator with gelatin/silica hybrid hydrogel (GSH). This redox hydrogel was characterized by UV-Vis, CV and EIS. The feasibility of the novel integrated biosensor for biotoxicity assay was demonstrated by measuring the heavy metal ions Hg(2+), Cu(2+) and Cd(2+) polluted water as the model toxicants. The results showed that the integrated biosensor was able to evaluate the water biotoxicity and the corresponding 50% inhibiting concentrations (IC50) are determined to be 21.2 μg mL(-1), 44 μg mL(-1) and 79 μg mL(-1), respectively. This integrated biosensor could achieve real-time monitoring of water quality and evaluation of biotoxicity. Moreover it avoids the waste and contamination of mediators, and also simplifies the assay process.