Ultrasensitive electrochemical determination of bisphenol A in food samples based on a strategy for activity enhancement of enzyme: Layer-by-layer self-assembly of tyrosinase between two-dimensional porphyrin metal–organic framework nanofilms

Tyrosinase (Tyr) was assembled layer-by-layer in an ultrathin copper–porphyrin MOF nanofilm (Tyr@Cu–TCPP) via a simple one-step solvothermal method, and a novel ultrasensitive electrochemical biosensor was fabricated for bisphenol A detection. Compared with native Tyr or a traditional surface-adsorbed structure of Tyr on ultrathin Cu–TCPP MOF nanofilm, the biosensor based on Tyr@Cu–TCPP exhibited significantly enhanced thermal and long-term storage stability, as well as acid/base tolerance. • Layer-by-layer assembly of Tyr in Cu-TCPP nanofilms by one-step synthesis. • The Cu-TCPP nanofilm creates a good environment for Tyr. • The biosensor showed significantly enhanced thermal stability, acid/base tolerance. Bisphenol A, as an endocrine disruptor, has aroused widespread attention for its safety. Electrochemical enzyme-based biosensor is a powerful tool for the determination of bisphenol A, but the instability of enzyme limits its practical application. Assembling biomacromolecules in metal–organic frameworks (MOFs) can preserve their biological functions in harsh environments. In this work, tyrosinase (Tyr) was assembled layer-by-layer in an ultrathin copper–porphyrin MOF nanofilm (Tyr@Cu–TCPP) via a simple one-step solvothermal method, and an ultrasensitive electrochemical biosensor was fabricated for bisphenol A detection. Compared with native Tyr or a traditional surface-adsorbed structure of Tyr on Cu–TCPP nanofilm, Tyr@Cu–TCPP retained superior enzymatic activity when exposed to elevated temperatures and extreme acidity or basicity, the sensor exhibited significantly enhanced thermal and long-term storage stability, as well as acid/base tolerance. In addition, the electrochemical biosensor based on Tyr@Cu–TCPP showed significantly enhanced sensing performance, including a wide linear range of 3.5 nM–18.9 μM, with a detection limit of 1.2 nM. For the first time, the fabrication of an electrochemical biosensor relying on enzyme assembled between two-dimensional MOF nanomaterial layers has been reported. This method greatly improves the activity and stability of the biosensor, and provides a promising strategy for promoting the application of enzyme biosensors in harsh detection environments, discovering and controlling environmental pollutants and food hazards.