RGD peptide-conjugated polydopamine nanoparticles loaded with doxorubicin for combined chemotherapy and photothermal therapy in thyroid cancer.

[OBJECTIVE] To construct polydopamine (PDA)-based nanoparticles (NPs) for combined chemotherapy (CT) and photothermal therapy (PTT) of thyroid tumors by conjugating doxorubicin (DOX) via Schiff base reaction and decorating with RGD peptide.

[METHODS] PDA NPs were synthesized using dopamine hydrochloride (DA) as the raw material and reacted with DOX-PEG-NH to obtain PDA-DOX NPs. Subsequently, RGD peptide was coupled with PDA-DOX NPs for modification. Their size, charge, and shape were characterized using DLS and SEM. The assembly of DOX was verified by ultraviolet-visible spectroscopy (UV-Vis), and the release efficiency of DOX under different pH conditions was calculated. The antitumor effect of RGD@PDA-DOX was validated in KTC-1 cells and tumor-bearing nude mice.

[RESULTS] The prepared RGD@PDA-DOX exhibited excellent dispersion, stability, and biocompatibility. PDA-DOX possessed superior photothermal conversion efficiency, capable of rapidly elevating the solution temperature within 5 min. In vitro studies revealed that the inhibitory rate of RGD@PDA-DOX combined with 808 nm laser on KTC-1 cells reached 92% (p < 0.05). In vivo experiments demonstrated that RGD@PDA-DOX exhibits no cytotoxicity. The modification with RGD peptides enables RGD@PDA-DOX to target tumor regions and accumulate over an extended period. Additionally, RGD@PDA-DOX, when combined with an 808 nm laser, significantly inhibits tumor growth.

[CONCLUSION] RGD@PDA-DOX can effectively accumulate in tumor regions and demonstrates excellent anti-tumor efficacy. It may serve as a feasible approach for the effective treatment of thyroid tumors, providing further evidence and data for clinical translation.