Phase Engineered Cu_xS-Ag₂S with Photothermoelectric Activity for Enhanced Multienzyme Activity and Dynamic Therapy.

Abstract

The insufficient exposure sites and active site competition of multienzyme are the two main factors to hinder its therapeutic effect. Here, a phase-junction nanomaterial (amorphous-crystalline Cu_xS-Ag₂S) is designed and prepared through a simple room temperature ion-exchange process. A small amount of Ag⁺ is added into Cu₇S₄ nanocrystals, which transforms Cu₇S₄ into amorphous phased Cu_xS and produces crystalline Ag₂S simultaneously. In this structure, the overhanging bonds on the amorphous Cu_xS surface provide abundant active sites for optimizing the therapeutic activity. Meanwhile, the amorphous state enhances the photothermal effect through non-radiative relaxation, and due to its low thermal resistance, phase-junction Cu_xS-Ag₂S forms a significant temperature gradient to unlock the optimized thermo-electrodynamic therapy. Furthermore, benefiting from the high asymmetry of the amorphous state, the material forms a spin-polarized state that can effectively inhibit electron-hole recombination. In this way, the thermoelectric effect can facilitate the enzyme-catalyzed cycle by providing electrons and holes, enabling an enhanced coupling of thermoelectric therapy with multienzyme activity, which induces excellent anti-tumor performance. More importantly, the catalytic process simulated by density-functional theory proves that Ag⁺ alleviates the burden on the Cu sites through favorable adsorption of O₂ and prevents active site competition.