Targeted Delivery of siRNA with pH-Responsive Hybrid Gold Nanostars for Cancer Treatment

Abstract

In this work, we report the engineering of gold nanostars (GNS) to deliver small interfering RNA (siRNA) into HepG2 cells. The ligand DG-PEG-Lipoic acid (LA)-Lys-9R (hydrazone) was designed to functionalize GNS, and create the nanoparticles named as 9R/DG-GNS (hydrazone). In the ligand, 2-deoxyglucose (DG) is the targeting molecule, polyethylene glycol (PEG) helps to improve the dispersity and biocompatibility, 9-poly-d-arginine (9R) is employed to provide a positive surface charge and adsorb negative siRNA, and hydrazone bonds are pH-responsive and can avoid receptor-mediated endosomal recycling. Compared to GNS alone, 9R/DG-GNS (hydrazone) showed superior transfection efficiency. The expressions of cyclooxygenase-2 (COX-2) in HepG2 and SGC7901 cells were significantly suppressed by siRNA/9R/DG-GNS (hydrazone) complex. Notably, 9R/DG-GNS (hydrazone) possessed low cytotoxicity even at high concentrations in both normal cells and tumor cells. The combination treatment of siRNA/9R/DG-GNS (hydrazone) complex inhibited the cell growth rate by more than 75%. These results verified that the pH-responsive GNS complex is a promising siRNA delivery system for cancer therapy, and it is anticipated that near-infrared absorbing GNS with good photothermal conversion efficiency can be potentially used for photothermal therapy of tumors.