Dual-Wavelength-Excited Afterglow Nanocomposites for Simultaneous In Situ Temperature Monitoring and Deep-Tissue Photothermal Sterilization

Herein, an afterglow nanocomposite was fabricated by grafting nano-sized photothermal agents (PTAs) Cu 1.96 S onto the surface of near-infrared persistent luminescent nanoparticle (PLNP), namely PLNP-Cu 1.96 S, via electrostatic adsorption. The nanocomposites exhibited excellent structural stability above the human arterial blood flow velocity (0.5 m/s). Meanwhile, the corresponding photothermal conversion efficiency of these nanocomposites reached 56% upon 808 nm laser excitation. Based on the sensitive ratiometric afterglow temperature detection performance of PLNP, a precise deep-tissue photothermal sterilization method using PLNP-Cu 1.96 S nanocomposites is proposed through a dual-wavelength excitation strategy (i.e., simultaneous in-situ afterglow-based real-time temperature monitoring are acquired upon 635 nm laser excitation, and photothermal sterilization is realized upon 808 nm laser excitation). The temperature sensitivity is determined to be above 0.058 K⁻¹, which is superior to that of fluorescence-based thermometers. Upon maximum permissible exposures for skin safety (808 nm, 0.4 W/cm 2 ) through 4-mm-thick tissue, the photothermal bactericidal rate of PLNP-Cu 1.96 S nanocomposites still can reach to 94%.