Interactions between quantum dots and dopamine coupled via a peptide bridge

Abstract

Colloidal quantum dots (QDs) have a large fraction of their atoms arrayed on their surfaces and are capped with bifunctional ligands, which make their photoluminescence highly sensitive to potential charge transfer. In this report, we exploited the interactions of CdSe/ZnS QDs and dopamine (DA) coupled via a peptide bridge arginine–glycine–aspartic acid–cysteine (RGDC) and modulated the fluorescence and photoresponse of the DA–CDGR–QDs system by specific trypsin activity. Results showed that the quenching of the QDs emission was highly dependent on proper linkage which indicated that the RGDC as bridge could promote the charge transfer between the QDs and DA. Interestingly, the presence of trypsin could specifically cleave the peptide substrate, resulting in the fluorescence and photoresponse recovery of DA–CDGR–QDs system that depended on the enzyme concentration. These proximity driven interactions provide new insights for constructing the sensing assemblies to detect other enzyme activity.