Chiral Nanozyme for Highly Enantioselective Detection of 3,4‐Dihydroxy‐D/L‐phenylalanine

Enantioselective sensing of 3,4‐dihydroxyphenylalanine (DOPA) enantiomers is highly significant in biology and pharmaceutics, yet developing sensors with high enantioselectivity and analyte‐specific output signals remains challenging. In this study, we constructed an L‐cysteine (Cys)‐Fe 2+ nanozyme through self‐assembly of L‐Cys and Fe 2+ . This nanozyme exhibited efficient peroxidase‐like activity, with a K cat value of 2.1 × 10 −9 M·s −1 ·µg −1 toward 3,3“,5,5”‐tetramethylbenzidine (TMB). When using D/L‐DOPA as a substrate, we observed higher catalytic efficiency for L‐DOPA than for D‐DOPA, with a selectivity factor of 1.6. Mechanistic studies revealed that this enantioselectivity originates from the preferential adsorption of D‐DOPA over L‐DOPA on the nanozyme surface, which impedes the oxidation kinetics by blocking substrate access to the active sites. These chirality‐specific changes induced in UV–vis absorption during catalysis enabled the establishment of analyte‐specific calibration curves for D‐DOPA, L‐DOPA, and enantiomeric compositions in D/L‐DOPA mixtures, achieving highly enantioselective sensing of DOPA enantiomers. This sensing platform demonstrated high sensitivity (limit of detection: 3.6 µM), excellent selectivity, and significant potential for practical applications. These findings provide novel insights for developing superior enantioselective sensors with high accuracy.