Biocompatible and multifunctional gold nanorods for effective photothermal therapy of oral squamous cell carcinoma

Herein, a cysteine-functionalized alginate was used to replace cytotoxic cetyltrimethylammonium bromide (CTAB) on gold nanorods (GNRs) by gold-thiol bonding. The characterization shows that the alginate-modified GNRs (GNR@Alg-Cys) were 137 nm in length (measured by zetasizer) with a negative surface charge (-28.4 mV). The GNR@Alg-Cys showed an intense absorption at 800 nm, indicating the potential of GNR@Alg-Cys for NIR-excited photothermal therapy (PTT). To target cancer cells, a cyclic peptide, c(RGDfK)KKK, was further modified on GNR@Alg-Cys (denoted as GNR@Alg-Cys/RGD). In vitro experiments reveal the apparently enhanced cell viability under a high dose of GNRs as well as the death of SAS-3 cell lines exposed to a single-wavelength laser (808 nm). The animal study revealed that the volume of GNR@Alg-Cys/RGD-treated laser-exposed tumor was reduced five times when compared with that in the case of the control group (PBS-treated tumor). Furthermore, the in vivo toxicity of GNR@Alg-Cys/RGD was evaluated, and no significant effect was observed on the functions of liver and kidneys after PTT.