Regulating the size of antimony nanoparticles to enhance the photo-response in the near-infrared region and anti-hepatoma cell activity.

Abstract

<h4>Introduction</h4>Antimony (Sb) has been used as a medication for centuries, while it has rarely been investigated in plasmonic phototherapy, partly due to the lack of effective liquid-phase controllable synthesis methods to construct Sb nanocrystals with an optimized absorption curve within the biological transparent window (near-infrared region), achieving more effective and less side-effect phototherapy.<h4>Methods</h4>Herein, an effective ligand-guided growth strategy was employed to synthesize Sb nanoparticles (Sb NPs) with high photothermal conversion efficiency (PTCE). The spatial electric field distribution of Sb NPs was simulated by the finite-difference time-domain (FDTD) method to validate their localized surface plasmon resonance (LSPR) effect. Sb NPs were coated with polydopamine (PDA) and polyethylene glycol (PEG) to enhance their biocompatibility. The synergistic anti-hepatoma activities of Sb NPs were evaluated via <i>in vitro</i> experiments.<h4>Results</h4>Sb NPs were successfully obtained via a ligand-guided growth strategy. Uv-vis absorption peak was observed to red-shift from 520 nm to 810 nm as the size of Sb NPs increased from 40 nm to 70 nm. Sb NPs achieve a PTCE of 59.3% under 808 nm resonant excitation and was favorable to photothermal therapy (PTT). Sb NPs also exhibit 660 nm laser responsiveness, producing reactive oxygen species (ROS) that enable photodynamic therapy (PDT). <i>In vitro</i> anti-BEL-7404 hepatoma cells experiments revealed that 660 nm/808 nm laser irradiation could inhibit proliferation, promote apoptosis, and induce G2/M phase blockage tendency, with combined irradiation exhibiting more significant effects.<h4>Conclusion</h4>The fabricated Sb-PDA exhibits synergistic PTT/PDT potential, though its <i>in vivo</i> efficacy and mechanisms warrant deeper investigation. LSPR-induced Sb-based nanomedicine may unlock diverse biomedical applications of semimetals.