Biocompatible Water-Soluble Silicon Quantum Dots for Photodynamic Cancer Therapy

This study reports the development of silicon quantum dots (SiQDs) designed as water-soluble and biocompatible materials for biomedical applications by functionalizing mixed surfaces of 10-Undecenoic acid (acid-SiQDs) and poly(ethylene oxide) (acid-PEO-SiQDs) through thermally induced hydrosilylation. The SiQDs exhibited exceptional biocompatibility with cell viability exceeding 95% and negligible toxicity at concentrations up to 500 μg/mL after 24 h of culture. In vitro photodynamic therapy (PDT) studies under low-level near-infrared (NIR) laser irradiation demonstrated significant therapeutic efficacy, reducing cancer cell viability to below 50% at concentrations of 250 μg/mL for acid-SiQDs and 50 μg/mL for acid-PEO-SiQDs after 10 min of irradiation. In vitro hemocompatibility of the SiQDs was investigated by measuring red blood cell hemolysis and aggregation, plasma coagulation, and platelet activation studies, which demonstrate that the surface modified SiQDs do not show adverse effects. Additionally, the SiQDs exhibited a red photoluminescent quantum yield exceeding 30%, further underscoring their structural stability and functional versatility. Collectively, these findings highlight the potential of acid-SiQDs and acid-PEO-SiQDs as safe, multifunctional platforms for enhancing cancer therapy through NIR irradiation while maintaining favorable blood compatibility, paving the way for their application in advanced biomedical technologies.