A bimetallic nanocatalyst for light-free oxygen sensitization therapy

Singlet oxygen (¹O₂) is extensively employed by reactive oxygen species (ROS)-based cancer therapies, such as photodynamic therapy (PDT) and chemodynamic therapy (CDT). However, the dependences of PDT on light and CDT on complex chemodynamic reactions greatly limit their ¹O₂-generating efficiencies. Here, we exploit strain and electronic effects to fabricate a bimetallic nanocatalyst by coating a gold nanorod (AuNR) with ~2 platinum (Pt) atomic layers (AuPt_0.09), which efficiently generates ¹O₂ from ground-state oxygen (³O₂) by electron-transfer-mediated spin reduction. Density functional theory reveals strain, and electronic effects promote the adsorption of ³O₂ onto AuPt_0.09, which dramatically enhances ¹O₂ generation and imparts AuPt_0.09, the highest catalytic constant ever reported for 3,3′,5,5′-tetramethylbenzidine oxidation to the best of our knowledge. With a pH-dependent catalytic activity, AuPt_0.09 realizes acidity-dependent antitumor effects both in vitro and in vivo, a proof-of-concept demonstration of autocatalytic bimetallic nanocatalyst for light-free oxygen sensitization therapy, which may open a new avenue for ¹O₂-centered therapeutics.