Designable NIR-II light triggered biocompatible Au NRs for highly efficient photothermal therapy of cervical cancer

Gold nanorods (Au NRs) hold great potential for photothermal therapy (PTT) of cervical cancer, but their clinical application is hindered by suboptimal absorbance in the second near-infrared (900-1700 nm, NIR-II) spectral window, synthetic heterogeneity, and cytotoxic surfactant residues. To overcome these limitations, we combined computational design with experimental synthesis and developed novel type of NIR-II-optimized Au NRs. Finite-difference time-domain simulations predicted that Au NRs exhibited 88 nm of length and 13 nm of diameter with a strong localized surface plasmon resonance (LSPR) peak at 1058 nm, enabling deep tissue penetration in the NIR-II spectral region. Experimentally, we synthesized highly uniform Au NRs@PEG nanoparticles (NPs) via a seed-growth method, achieving a 1026 nm absorption peak while replacing toxic cetyltrimethylammonium bromide (CTAB) with biocompatible polyethylene glycol (SH-PEG-5000). The Au NRs@PEG demonstrated exceptional photothermal conversion efficiency of 60.89%, excellent tumor accumulation, and minimal systemic toxicity. In vivo studies confirm effective tumor suppression of 93.5% under NIR-II light excitation, with the stability for repeated treatment cycles. In this work, we introduce a versatile paradigm for designing high-performance, clinically viable photothermal agents by means of rational optical engineering and surface modification.