摘要： Aqueous synthesis of glutathione (GSH) coated Ag2S quantum dots (QD) with strong emission in the medical imaging window (700-900 nm) were prepared from AgNO3. Variations in temperature, time, pH and sulfur source (Na2S and thioacetamide) were studied to tune the emission wavelength and intensity of QDs. The optimum synthesis condition to produce the smallest QDs (ca 7 nm) with the highest quantum yield (70 %) and excellent stability was determined as 50 ℃ and pH 10 where Na2S was used in 2 h reactions. Cytotoxicity was evaluated with MTT assay on HT29 and MCF7 cancer cell lines and indicated no significant toxicity of QDs up to 200 μg/mL. Photothermal Therapy (PTT) potential was first investigated by 795 nm, continuous-wave fiber coupled diode laser using aqueous solutions of QDs and then on HT29 and MCF7 cells. QD (150 μg/mL) treated MCF7 cells almost quantitatively died after 10 min irradiation at 795 nm (700 mW, 1.82 W/cm2) and the viability of HT29 cells dropped to 40%. Most cell death was late apoptotic/necrotic. This study indicates that such laser irradiation procedure and the QDs are safe yet, their combination provides a dramatic cell death upon short laser treatment. PTT coupled with strong intracellular optical signal promotes Ag2S-GSH QDs as potential theranostic nanoparticles.