A novel pH-sensitive targeting polysaccharide-gold nanorod conjugate for combined photothermal-chemotherapy of breast cancer

[Display omitted] •AHA-decorated bifunctionalized HECS-GNR conjugate was developed.•DOX was loaded onto the conjugate via hydrazone linkage.•The conjugate displayed pH-responsive surface charge reversal and drug release.•The conjugate exhibited synergetic photothermal chemotherapy of breast cancer cells. Chemo-photothermal combination therapy is a promising strategy for cancer treatment. In this study, to achieve the combined photothermal-chemotherapy of breast cancer, a pH-sensitive oxidized hyaluronic acid-decorated dihydroxyphenyl/hydrazide bifunctionalized hydroxyethyl chitosan (DHHC)-gold nanorod (GNR) conjugate was developed. DHHC was synthesized by successive dihydroxyphenylation and hydrazidation of hydroxyethyl chitosan through carbodiimide reaction and click chemistry, respectively. The conjugate was obtained by chemically bonding DHHC onto GNR via Au-catechol bonds. Doxorubicin (DOX) was loaded onto the conjugate via an acid-labile hydrazone linkage with a drug loading content of 5.1%. DOX-loaded conjugate displayed good stability in neutral aqueous solutions and exhibited pH-responsive drug release and surface charge reversal behaviors. In vitro biological studies indicated that the conjugate could be effectively internalized by breast cancer MCF-7 cells and synergistic therapeutic effects were demonstrated, suggesting its great potential in combined photothermal-chemotherapy of breast cancer.