Dipeptide-Capped Copper Nanoparticles as Chiral Nanozymes for Colorimetric Enantioselective Recognition of 3,4-Dihydroxy-D,L-phenylalanine

In pharmaceutical and biomedical applications, it is imperative to identify chiral molecules. However, colorimetric sensing enantiomers relying on chiral nanozymes is still a major challenge in chirality recognition. Herein, we report a facile and simple strategy to prepare copper nanoparticles (CuNPs) using D- cysteine-D-histidine (DCDH), D-cysteine-L-histidine, and L-cys-teine-D-histidine as the capping agents. All of these CuNPs exhibited peroxidase-mimicking activity in 3,3 ',5,5 '-tetramethyl-benzidine oxidation and presented chiral selectivity toward 3,4dihydroxy-D,L-phenylalanine (D,L-DOPA). More importantly, DCDH-modified CuNPs (DCDH@CuNPs) showed higher peroxidase-mimicking catalytic activity in the presence of D- DOPA than L-DOPA. This demonstrates that in the stereoselective recognition CuNPs play the catalytic center role and chiral dipeptide ligands play the inducer role. The insights obtained from this study not only provide information to deeply understand the molecular principles of colorimetric chiral recognition upon CuNPs but also guide the design of dipeptide-based chiral nanozymes toward enantiomers.

Automated summary

In this study, copper nanoparticles (CuNPs) were prepared using different chiral dipeptides as capping agents. These CuNPs exhibited peroxidase-mimicking activity and chiral selectivity towards 3,4-dihydroxy-D,L-phenylalanine (D,L-DOPA). The D- cysteine-D-histidine-modified CuNPs showed higher catalytic activity in the presence of D-DOPA, indicating the important role of CuNPs in stereoselective recognition. This study provides insights into the molecular principles of colorimetric chiral recognition using CuNPs and guides the design of dipeptide-based chiral nanozymes.