An AIE Controlled "Off-On" Cu²⁺-Sensitive Probe for Early Detection of Renal Fibrosis

Early detection of renal fibrosis (RF) is very important given that it is irreversible when it progresses to the terminal stage. A key marker of RF pathogenesis is activation of myomyofibroblasts, and its targeted imaging may be a promising approach for early detection of RF, but no study has directly imaged activation of renal myomyofibroblasts. Cu²⁺ plays a major role in the fibrotic activity of myofibroblasts. Herein, inspired by that Cu²⁺ can complex with bovine serum albumin (BSA), BSA-Ag₂S quantum dots (QDs) with aggregation-induced emission (AIE) property are synthesized. Then BSA-Ag₂S QDs are modified by chitosan (CS) with renal targeting and hyaluronic acid (HA) with myofibroblast targeting to obtain the AIE assay system (QDs@CS@HA). The system is simple to synthesize, and produces a rapid NIR fluorescence signal turn-on response and a low detection limit of 75 × 10^-9 m to Cu²⁺. In addition, cellular and animal experiments have shown that QDs@CS@HA has good biosafety and cell-targeted imaging capability for RF. Based on the successful application of QDs@CS@HA and the mechanism of RF progression in early RF detection, it is expected that QDs@CS@HA may detect RF before the appearance of clinical symptoms.