Optical assay using B-doped core-shell Fe@BC nanozyme for determination of alanine aminotransferase.

B-doped core-shell Fe@BC nanozyme was synthesized. The peroxidase (POD) like activity of Fe@BC nanozyme was studied and utilized for detecting the activity of alanine aminotransferase (ALT). In the presence of ALT as well as ALT co-substrates L-alanine and α-ketoglutarate, L-glutamate is generated. The following catalytic oxidation of L-glutamate by glutamate oxidase leads to the generation of H2O2. The POD-like activity of Fe@BC can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to oxTMB in the presence of H2O2, generating a blue-colored compound. Through the detection of the amount of H2O2 generated, ALT activity can be determined through measuring the absorbance intensity variation at 450 nm. The limit of detection of the assay is 4 U/L, with a linear range from 10 to 1000 U/L. For human serum samples, the ALT levels determined by our assay are comparable to those determined by the hospital with a correlation coefficient of 0.991, demonstrating the reliability of our assay results.