Hollow Ag-Cu7S4 Schottky junction endows polycaprolactone scaffold with thermal-electric-catalytic effect for promoting osteogenesis and anti-infection

Preparing a hollow Ag-Cu 7 S 4 with lattice defect, improving Seebeck coefficient and thermoelectric effect. • Ag 3d band hybridization narrows bandgap, promotes electron-hole separation and thermoelectric-catalytic ROS generation. • Scaffold enables efficient photothermal conversion and synergistic thermoelectric output under 808 nm NIR-I irradiation. • Thermoelectric boost osteogenesis: 2.1±0.3-fold upregulation of ALP/ARS and 55±2% increase in osteogenic gene and protein. • ROS cascade photothermal disrupt biofilm and GSH, achieving 92±2% ( S. aureus ) and 94.2±2.1% ( E. coli ) antibacterial rates. Cuprous sulfide (Cu 7 S 4 ) shows great potential for thermoelectric treatment of infectious bone defects due to its favorable carrier mobility and thermal conductivity. Nevertheless, its applicability remains constrained by suboptimal carrier concentration, rapid electron-hole recombination, and poor near-infrared (NIR) absorption. Herein, silver ions (Ag + ) were incorporated into Cu 7 S 4 via cation exchange to form hollow Ag-Cu 7 S 4 nanoparticles, and subsequently embedded into polycaprolactone (PCL) to prepare PCL/Ag-Cu 7 S 4 scaffolds. Specifically, Ag utilizes its similar atomic radius to partially substitute for Cu, introducing lattice defects to enhance phonon scattering, further reducing lattice thermal conductivity, thereby enhancing thermoelectric therapy (TET). Meanwhile, hybridization of Ag 3d energy levels with the Cu 7 S 4 band structure optimizes the Fermi level, narrowing the bandgap, thus boosting electron-hole pairs generation and enhancing the thermoelectric catalytic generation of ROS. The scaffolds exhibit excellent NIR absorption and photothermal effect (PTT). The enhanced phonon scattering and conductivity significantly optimize the thermoelectric figure of merit. TET utilized electrical stimulation to promote osteogenic differentiation, upregulating Alkaline phosphatase and Alizarin red by 2.1 ± 0.3-fold and increasing osteogenesis-related mRNA and protein by 55 ± 2%. The narrowed bandgap boosts thermoelectric catalytic ROS generation, ROS synergistically with PTT destroyed the defense systems, achieving antibacterial rates of 92 ± 2% ( S. aureus ) and 94.2 ± 2.1% ( E. coli ). Download: Download high-res image (151KB) Download: Download full-size image