Trienzymatic biosensor for the determination of inorganic phosphate Original Research Article

A biosensor for phosphate detection has been fabricated using a mixture of maltose phosphorylase (MP), mutarotase (MR), and glucose oxidase (GOD) entrapped in an inorganic laponite clay. The response of the biosensors to phosphate and glucose additions was measured by potentiostating the modified electrodes at 0.6 V versus Ag/AgCl in order to oxidize the enzymatically generated hydrogen peroxide. The bioelectrochemical response of the biosensor for phosphate detection is strongly affected by the ratio of each enzyme in the enzyme–clay mixture. The optimum pH and temperature of the biosensor are 6.5 and 40°C. Under these optimum conditions, the phosphate sensitivity and the linear range are 52.4 mA M−1 cm−2 and 1–50 μM, respectively. The maximum response current of the biosensor is stable at least for 2 weeks, a 30% decay of initial activity was observed after 42 days at 4°C.