Synthesis and characterization of NIR-responsive Au(rod)@pNIPAAm-PEGMA nanogels as vehicles for delivery of photodynamic therapy agents

A near-infrared (NIR)-responsive Au(rod)@pNIPAAm-PEGMA nanogel was synthesized in two steps, growing a PEGMA monolayer on the surface of gold nanorods (AuNRs), followed by in situ polymerization and cross-linking of N-iso-propylacrylamide (NIPAAm) and poly-(ethylene glycol)-methacrylate (PEGMA). The AuNRs and Au(rod)@pNIPAAm-PEGMA nanogel were characterized by UV–vis spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy, respectively. The lower critical solution temperature of the Au(rod)@pNIPAAm-PEGMA nanogel could be tuned by changing the molar ratio of NIPAAm/PEGMA. The NIR-mediated drug release behavior of the Au(rod)@pNIPAAm-PEGMA nanogel was studied with zinc phthalocyanines (ZnPc(4)) as a drug model. It was also demonstrated that the loaded ZnPc(4) could keep the capability of generating singlet oxygen, and the in vitro study showed a great photodynamic therapy (PDT) effect on Hela cells. It thus indicated the potential of this Au(rod)@pNIPAAm-PEGMA nanogel for application as a drug carrier in PDT, which might make contributions to oncotherapy.