Regenerated keratin-encapsulated gold nanorods for chemo-photothermal synergistic therapy.

Gold nanorods (AuNRs) have been widely applied to photothermal therapy against cancer. However, the chemically synthesized AuNRs such as that via seed-mediate method usually demonstrated a high cytotoxicity due to the existence of cetyltrimethylammonium bromide (CTAB) coating. In this work, keratin, a family of cysteine-rich structural fibrous proteins was used for the first time to encapsulate AuNRs by a simple mixing method. Compared with CTAB-AuNRs, the keratin-encapsulated AuNRs (AuNRs@Kr) showed an improved colloid stability and good biocompatibility including low cytotoxicity and hemolytic effect. Moreover, AuNRs@Kr exhibited great potential as drug carriers with redox-responsive drug release behavior, due to the high concentration of disulfide crosslinking in keratin coating, and the DOX-loaded AuNRs@Kr demonstrated higher chemo-photothermal synergistic therapy efficiency against 4T1 cells compared with either free DOX or AuNRs@Kr alone, suggesting a promising nanoplatform for cancer therapy.