In vitro studies demonstrated that HA/anti-miR-21/PPAuNCs could enhance intracellular DOX accumulation in DOX-resistant HCC cells (HepG2/ADR cells) and increase the sensitivity to DOX of HepG2/ADR cells through upregulating PTEN protein expression mediated by anti-miR-21 and downregulating P-gp protein expression mediated by the hyperthermia of HA/PPAuNCs upon mild near-infrared irradiation.