Development of near-infrared region luminescent N-acetyl-L-cysteine-coated Ag2S quantum dots with differential therapeutic effect

Aim: N-acetyl-L-cysteine (NAC) is a free radical scavenger. We developed NAC-coated Ag2S (NAC-Ag2S) quantum dot (QD) as an optical imaging and therapeutic agent. Materials & methods: QDs were synthesized in water. Their optical imaging potential and toxicity were studied in vitro. Results: NAC-Ag2S QDs have strong emission, that is tunable between 748 and 840 nm, and are stable in biologically relevant media. QDs showed significant differences both in cell internalization and toxicity in vitro. QDs were quite toxic to breast and cervical cancer cells but not to lung derived cells despite the higher uptake. NAC-Ag2S reduces reactive oxygen species (ROS) but causes cell death via DNA damage and apoptosis. Conclusion: NAC-Ag2S QDs are stable and strong signal-generating theranostic agents offering selective therapeutic effects.