Subphthalocyanines as electron mediators in biosensors based on phenol oxidases

Abstract

The electron mediator properties of three subphthalocyanines (SubPcs) [hexa-chloro boron subphthalocyanine (ClSubPc), tri-tert-butyl boron subphthalocyanine (t-BuSubPc) and hexa-phenoxy boron subphthalocyanine (PhOSubPc)] in Tyrosinase and Laccase biosensors (deposited on ITO glass) for the detection of catechol and hydroquinone were evidenced. A particularly remarkable performance was observed in the PhOSubPc-Tyr sensor, which takes account of the π-π interactions between subphthalocyanine rings and the active sites of the enzymes. Mediated electron transfer between redox enzymes and the ITO electrode improved the limits of detection by one order of magnitude, reaching 10−7 mol·L−1 values. Studies at increasing scan rates confirmed the improvement of the charge transfer rates caused by the presence of the SubPcs. A bioelectronic tongue formed by an array of the SubPc based biosensors has been able to discriminate red wines according to their Total Polyphenol Index.