A self-correcting fluorescent assay of tyrosinase based on Fe-MIL-88B-NH2 nanozyme

A self-correcting fluorescent assay of tyrosinase (TYR) was developed by utilization of Fe-MIL-88B-NH 2 as a peroxidase-like nanozyme and a capture probe. Fe-MIL-88B-NH 2 nanozyme was selected as an electron donor, and the oxidization product (dopamine- o -quinone) acts as an energy acceptor. First, TYR catalyzes the oxidation of tyramine hydrochloride to dopamine and then to dopamine- o -quinone. Second, Fe-MIL-88B-NH 2 with intrinsic peroxidase-like activity decomposes H 2 O 2 to produce ·OH radicals, which further accelerate the oxidation of dopamine to dopamine- o -quinone. Excessive H 2 O 2 and ·OH radicals reduce the interferences from ascorbic acid at the same time providing a self-correcting ability. Dopamine- o -quinone reacts with -NH 2 groups on the ligand of Fe-MIL-88B-NH 2 through Michael reaction which results in fluorescence quenching. Under 365-nm excitation, the fluorescence emission intensity at 452 nm gradually decreased with increasing TYR concentration varying from 0 to 10 U mL −1 . The linear range is from 1 to 5 U mL −1 and the detection limit is 0.05679 U mL −1 . This self-correcting fluorescent assay of tyrosinase exhibits good sensitivity and selectivity which is also successfully applied for tyrosinase inhibitor detection. Graphical abstract Schematic representation of fluorescent assay for tyrosinase determination based on Fe-MIL-88B-NH 2 nanozyme. A self-correcting fluorescent assay for tyrosinase was developed based on the Fe-MIL-88B-NH 2 nanozyme.