Tyrosinase nanocapsule based nano-biosensor for ultrasensitive and rapid detection of bisphenol A with excellent stability in different application scenarios

Bisphenol A (BPA), one of the most important endocrine disrupting chemicals, is a threat to human and wildlife health. Electrochemical enzyme biosensor has been regarded as ideal alternative analytical technique for ultrasensitive and rapid detection of BPA, while the unstable and easily deactivated nature of enzyme limits its development. In order to improve the stability of enzyme, tyrosinase was chosen as a model enzyme, and tyrosinase nanocapsules (nTyr) were prepared by encapsulating a single tyrosinase molecule into a thin network polymer shell through in-situ polymerization method in aqueous solution. The characterization of particle size distribution, TEM and FTIR indicated the successful formation of single tyrosinase molecule nanocapsule. And the porous network polymer shell of nTyr ensured the maintenance of tyrosinase activity and fast substrate transportation. The obtained nTyr was used to construct an electrochemical biosensor for BPA detection, exhibiting a low detection limit of 12 nmol L-1 and a wide linear range from 5 × 10-8 to 2 × 10-6 mol L-1. Compared with native tyrosinase, the nTyr based biosensor displayed dramatically enhanced stability including thermal stability, organic solvent tolerance and acid/base tolerance. The excellent performance of nTyr based biosensor was not only attributed to the protection of biocompatible rigid polymer shells, but also the multipoint covalent attachments between tyrosinase cores and polymer shells. The robust biosensor was further used for rapid detection of BPA leached from plastic products with satisfactory results. The nTyr based nano-biosensor provides a prospective solution to resolve the stability problem of enzyme biosensors in different application scenarios.