Ultrasmall Ligand-Protected Ag<sub>7</sub> Nanoclusters Enable Dual-Mode Reactive Oxygen Species Generation under Dark and Near-Infrared Irradiation.
basic_science · Level V
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- Record sourced from PubMed, PMID 42208022.
- Also identified by DOI 10.1021/acsnano.6c01532.
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Abstract
Ultrasmall silver nanoclusters, Ag<sub>7</sub> NCs protected by MBISA (MBISA = 2-mercapto-5-benzimidazolesulfonic acid sodium salt), are presented as a dual-mode nanoplatform enabling complementary reactive oxygen species (ROS) activity under dark and near-infrared (NIR) light conditions. In darkness, Ag<sub>7</sub> NCs catalyze hydrogen peroxide decomposition through electronically differentiated Ag sites, concurrently generating hydroxyl radicals (•OH) and molecular oxygen (O<sub>2</sub>). XPS analysis demonstrates that the electronically differentiated Ag sites are preserved after H<sub>2</sub>O<sub>2</sub> exposure, indicating chemical robustness rather than sacrificial oxidation. Under 730 nm NIR irradiation, photoexcited Ag<sub>7</sub> NCs transfer energy to the <i>in situ</i>-generated O<sub>2</sub>, yielding singlet oxygen (<sup>1</sup>O<sub>2</sub>). The H<sub>2</sub>O<sub>2</sub>-driven O<sub>2</sub> supply can functionally support subsequent <sup>1</sup>O<sub>2</sub> generation under NIR irradiation. This cooperative mechanism enables stimulus-dependent activation of complementary ROS pathways for synergistic chemo- and photodynamic therapy. Ag<sub>7</sub> NCs exhibit excellent stability, renal clearance, and biosafety, achieving potent tumor regression and metastasis suppression <i>in vivo</i>. These findings position Ag<sub>7</sub> NCs as a molecularly defined nanocluster platform with redox-active behavior and complementary ROS for precision cancer therapy.