Colorimetric Recognition of 3,4-Dihydroxy-D,L-phenylalanine with Tetrapeptide-modified Copper Nanoparticles as Chiral Nanozymes

T he construct of artificial nanocatalyts by simulating natural enzymes and thereby bringing new properties for practical applications is still a challenging task to date. In this study, chiral tetrapeptide ( L -phenylalanine- L -phenylalanine- L -cysteine- L -histidine)-engineered copper nanoparticles (FFCH@CuNPs) were fabricated as an artificial peroxidase (POD). More interestingly, the nano-catalysts exhibited chiral identification function. In comparison with other nanocatalysts like L -cysteine-, L -histidine-, chiral dipeptide ( L -cysteine- L -histidine)-, or chiral tripeptide phenylalanine- L -cysteine- L -histidine)-modified CuNPs, FFCH@CuNPs demonstrated a higher POD-mimetic catalytic activity in the 3,3′,5,5′-tetramethylbenzidine (TMB)-H 2 O 2 system and stronger enantioselectivity in the recognition of 3,4-dihydroxy- D , L -phenylalanine ( D , L -DOPA) enantiomers. Considering the strength difference between the intermolecular hydrogen bonding and the π - π interactions, the principle behind the chiral discrimination of D , L -DOPA was explored. Furthermore, contents levels of surface Cu 2+ ions and hydroxyl radicals were found in the FFCH@CuNPs-D-DOPA-TMB-H 2 O 2 system than in the FFCH@CuNPs-L-DOPA-TMB-H 2 O 2 system. Based on these results, a protocol for distinguishing between D , L -DOPA enantiomers through colorimetric recognition was established. This study provides a new insight into design and fabrication of oligopeptides@CuNPs-based chiral nanozymes with improved catalytic performance and features additional to those of natural enzymes.