AuPd heterostructured nanoplates: in vitro near-infrared photothermal agents for combating multidrug-resistant bacteria

Abstract

We introduce AuPd heterostructured nanoplates (HNPs) as a potent photothermal platform for targeting multidrug-resistant (MDR) bacteria in vitro. Synthesized through a seeded growth method, these structures feature two distinct 2D morphologies: one with zig-zag edges and another with island-like domains distributed across the surface. Both designs maximize Au/Pd interface density while preventing full encapsulation—a balance crucial for maintaining strong LSPR properties alongside Au/Pd synergy. The HNPs achieve a high photothermal conversion efficiency of 64.7% under 808 nm laser irradiation and 46.5% under 1064 nm laser irradiation, enabling the efficient photothermal ablation of clinically relevant MDR pathogens such as MRSA in laboratory models and significantly inhibiting biofilm formation in vitro. Combining experimental characterization with theoretical modeling, we demonstrate that this exceptional performance stems from an electronic synergy at the heterointerface that promotes non-radiative plasmonic decay, together with lattice strain that fine-tunes the local electronic structure for optimal near-infrared absorption. This work establishes a strong in vitro proof-of-concept for these heterostructures and provides a clear design principle for engineering advanced photothermal nanomaterials.