Selective electrochemical sensing of bisphenol derivatives using novel bioelectrode of agarose-guar gum-graphene oxide immobilized with tyrosinase

Bisphenols (BPs) are widely used in manufacturing of recyclable plastic products that are potentially toxic to human beings. In the current investigation, an electrochemical sensor based on a novel bioelectrode of agarose-guar gum-graphene oxide (A-G-GO) immobilized with tyrosinase was developed for bisphenols detection. The sensor was responsive towards six BP derivatives (A, F, E, B, Z and AP) while being non-responsive towards bisphenols S and AF. Formation of A-G-GO composites was confirmed by various analytical techniques. The electrochemical characterization indicated enhanced charge transfer abilities of the composites that helped in improving sensitivity. Mechanism of sensing involved enzymatic oxidation of bisphenols to corresponding o-bisphenols and subsequently their reduction on designed bioelectrodes at a potential of 80 mV. The sensor exhibited differential sensitivity towards varied BPs with linear dynamic response in the concentration range of 50–1000 µM and limit of detection ranging from 5 to 50 µM. Based on apparent Km values exhibited by tyrosinase, differential sensitivity towards BPs could be explained. The biosensor was found to be highly selective for bisphenol detection over other tyrosinase substrates with enhanced storage stability of 150 d. The proposed bioelectrode could successfully be used for measurement of bisphenols from plastic food packing material thus demonstrating its practical utility.