Small gold nanorods laden macrophages for enhanced tumor coverage in photothermal therapy.

One of the challenges to adopt photothermal ablation clinically is optimization of the agent delivery in vivo. Herein, a cell-mediated delivery and therapy system by employing macrophage vehicles to transport 7 nm diameter Au nanorods (sAuNRs) is described. Owing to the small size, the sAuNRs exhibit much higher macrophage uptake and negligible cytotoxicity in comparison with commonly used 14 nm diameter AuNRs to achieve healthy BSA-coated sAuNRs-laden-macrophages. By delivering BSA-coated sAuNRs to the entire tumor after intratumoral injection, the BSA-coated sAuNRs-laden-macrophages show greatly improved photothermal conversion almost everywhere in the tumor, resulting in minimized tumor recurrence rates compared to free BSA-coated sAuNRs. Our findings not only provide a desirable approach to improve the photothermal therapy efficiency by optimizing the intratumoral distribution of the agents, but also expedite clinical application of nanotechnology to cancer treatment.