Grain Boundaries Assisted Construction of Pt Colloidosomes for Tumor Catalytic Therapy Enhanced by Near-Infrared Photon-Excited Hot Electrons

Abstract Noble metal nanoparticles (NPs) are photo-responsive substrates that generate hot electrons under light excitation, and these hot electrons enhance the catalytic capability of the NPs, which is useful in many applications. For ultrasmall (≤ 5 nm) Pt NPs with excellently catalytic performance, it is challenging to utilize near-infrared (NIR) light-excited hot electrons to enhance the nanozyme activities of Pt NPs for tumor catalytic therapy because ultrasmall Pt NPs have no obvious absorption from the visible light band to the NIR band. Herein, we report on constructing Pt colloidosomes (Cs) with ultrasmall Pt NPs to elevate NIR light absorption to excite multitudes of hot electrons. The successful photon-to-electron conversion is based on the high density of electron states (d-band) at the Fermi energy in the Pt system, which leads to a high probability of generating NIR photon-excited hot electrons. NIR light absorption of Pt Cs is optimized by introducing grain boundaries (GBs) defects in Mn3O4 precursors by laser irradiation in liquids. Moreover, NIR photon-excited hot electrons largely promote the self-cascade catalytic production of reactive oxygen species (ROS) for enhanced tumor therapy. This study first validates the generation of hot electrons in the Pt nanostructure under NIR light irradiation by assembling ultrasmall Pt NPs, and then demonstrates the Pt Cs to be highly promising as efficient photo-responsive nanozymes with integrated photoactivity and chemical activity.