Organic nano-quantum dots of salvianolic acid B modified with photosensitive cypate for the diagnosis and treatment of myocardial ischemia-reperfusion injury.

Salvianolic acid B (SaB) demonstrates significant cardioprotective effects against myocardial ischemia-reperfusion injury (I/R). However, its clinical application is limited by rapid metabolism and poor bioavailability. To address this, we synthesized SaB-loaded organic quantum dots (SaB@qd) via a hydrothermal method and functionalized them with the near-infrared (NIR) dye cypate (SaB@qd@Cy). Proteomic analysis of cardiac tissues from I/R model rats identified SIRT2 as a key downregulated protein. Molecular docking and cell membrane chromatography confirmed SaB as a natural SIRT2 agonist, binding specifically to the SER-263 residue. SaB@qd@Cy enhanced myocardial SaB accumulation by 3.2-fold compared to free SaB (P < 0.01). In vivo, SaB@qd@Cy reduced the infarct area by 41 % (compared to 28 % reduction by mitochondrial-targeted CoQ10 nanoparticles) and attenuated inflammatory cytokine expression (IL-1β, TNF-α) via the SIRT2/NLRP3 pathway. Additionally, cypate enabled real-time NIR imaging of ischemic borders, with a temperature increase of 15.3 ± 1.2°C under 808 nm laser irradiation. This study presents a novel theranostic nanoplatform that integrates natural compounds with photoresponsive quantum dots for targeted therapy and intraoperative imaging in I/R management.