Polydopamine-coated Au-Ag nanoparticle-guided photothermal colorectal cancer therapy through multiple cell death pathways.

Nanoparticles are emerging as a new therapeutic modality due to their high stability, precise targeting, and high biocompatibility. Branched Au-Ag nanoparticles with polydopamine coating (Au-Ag@PDA) have strong near-infrared absorbance and no cytotoxicity but high photothermal conversion efficiency. However, the photothermal activity of Au-Ag@PDA in vivo and in vitro has not been reported yet, and the mechanism underlying the effects of photothermal nanomaterials is not clear. Therefore, in this study, the colorectal cancer cell line HCT-116 and nude mice xenografts were used to observe the photothermal effects of Au-Ag@PDA in vivo and in vitro. The results suggest that Au-Ag@PDA NPs significantly inhibited cell proliferation and induced apoptosis in colorectal cancer cells. Moreover, Au-Ag@PDA NP-mediated photothermal therapy inhibited the growth of tumors at doses of 50 and 100 μg in vivo. The mechanisms through which Au-Ag@PDA NPs induced colorectal cancer cell death involved multiple pathways, including caspase-dependent and -independent apoptosis, mitochondrial damage, lysosomal membrane permeability, and autophagy. Thus, our findings suggest that Au-Ag@PDA NPs could be used as potential antitumor agents for photothermal ablation of colorectal cancer cells.