Biocompatible and structurally stable near-spherical PLNP@PDA@PW12 nanoplatforms for precise temperature sensing and photothermal therapy

Abstract

Near-spherical core-shell PLNP@PDA nanoplatforms with an average diameter of 58.6 nm were successfully synthesized by covalently conjugating persistent luminescent nanoparticles (Zn₂Ga_2.96Ge_0.75O₈:Cr³⁺_0.02,W⁶⁺_0.01@SiO₂-NH₂, PLNPs) with polydopamine (PDA) photothermal agents via Michael addition and Schiff base reactions. Compared to electrostatic self-assembly nanoplatforms, the constructed core-shell PLNP@PDA@PW₁₂ nanoplatforms (58.8 nm) maintained structural integrity even after high-speed of 4 m/s (ten times higher than the average blood flow velocity) simulated circulation for 1 h, demonstrating their remarkable structural stability attributed to the increased interfacial contact area and strong interactions between PLNPs and PDA. These core-shell nanoplatforms, benefiting from the inherent biocompatibility of PDA and the modification of phosphotungstic acid (PW₁₂), exhibited excellent biosafety, maintaining 97.7% viability of mouse fibroblast cells (L929) at 200 μg/mL. In particular, the constructed core-shell nanoplatforms exhibited a high photothermal conversion efficiency of 49.7% under 635 nm excitation, owing to the pronounced photothermal effect of PDA. In vitro tests demonstrated bacterial eradication rates of 93.6% against Staphylococcus aureus (S. aureus) and 94.4% against Escherichia coli (E. coli) after four treatments with a human-safe laser dose (0.2 W/cm²) penetrating through 3 mm of tissue. In in vivo bacterial-infected wound models, the PLNP@PDA@PW₁₂ nanoplatforms increased the local tissue temperature within the wound under 635 nm laser irradiation, significantly inhibiting bacterial infection and accelerating wound healing. These PDA-based core-shell nanoplatforms with superior stability, biocompatibility, tissue-penetrating antibacterial capacity, and afterglow-temperature-guided precision photothermal therapy are highly promising candidates for clinical applications.