Modulation by Co (II) Ion of Optical Activities of L/D-glutathione (GSH)-modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection

Abstract

Chiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co²⁺ can modulate the luminescence performance of L/D-glutathione (GSH)-modified copper nanoclusters (L/D-Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223-fold with their distribution regulating from the ultraviolet to visible region. One Co²⁺ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN₂O₂. On this basis, dual-modal chiral and luminescent signals of Co²⁺ coordinated L/D-Cu NCs (L/D-Co-Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co²⁺. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L-Co-Cu NCs, and 5.35 μM and 4.69 nM for D-Co-Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio-targets.

Keywords: Assembly; Chirality; Coordination; Nanoclusters; Optical activities.