Silicon nanowires decorated with gold nanoparticles via in situ reduction for photoacoustic imaging-guided photothermal cancer therapy

Abstract

Photothermal therapy (PTT) in the first near-infrared (NIR-I) window has made great progress in the treatment of solid tumors, while only a few PTT agents in the second NIR (NIR-II) region have been studied. Here, we synthesized silicon nanowires decorated with gold nanoparticles (Si–Au) with excellent absorption both in NIR-I at ∼700 nm and NIR-II at ∼1064 nm, which was attributed to the composites of Au nanoparticles and Si nanowires. After surface modification with mercaptosuccinic acid (TA), the TA–Si–Au nanocomposites had good biocompatibility. Utilizing the high absorbance in NIR-II at 1064 nm, Si–Au nanocomposites with a photothermal conversion efficiency of 24.1% were used as photothermal agents (PTAs). Both in vitro and in vivo experiments showed a good photothermal effect. Under laser irradiation in NIR-I, TA–Si–Au nanocomposites also showed highly efficient PA imaging of mouse breast cancer cells (4T1) after intratumoral injection. This is the first report wherein Au–Si nanocomposites have served as excellent PTT agents in the NIR-II region and PA imaging agents in the NIR-I window, which might hold great promise for the treatment of deep solid tumors.