Fabrication of novel PNIPAM@GO microspheres loaded with dual drugs featuring on-demand drug release capability

In this research, we successfully prepared a new kind of core-shell microspheres (PNIPAM@GO) composed of hydrophilic poly (N-isopropyl acrylamide) (PNIPAM) nanoparticles as the core and amphiphilic graphene oxide (GO) nanosheets as the shell through hydrogen bonding and self-assembly in organic solvent. The temperature-sensitive behavior of the PNIPAM core made its average size decrease from 888.3 nm to 630.3 nm with temperature increasing from 25°C to 50°C. And the GO shell could give PNIPAM@GO microspheres remarkable photothermal effects in water under NIR laser irradiation (808 nm) for 20 min. Further, doxorubicin (DOX) and 5-fluorouracil (5-FU) were loaded into the core and the shell with loading efficiency of 81% and 11%, respectively. By turning on/off NIR irradiation, the PNIPAM@GO microspheres could respond to the heat generated from GO shell by volume shrinkage, thus on-demand controlling the drug release. The in vitro biological assessment verified that the samples prepared here were biocompatible. The developed platform shows a potential application in chemo-photothermal therapy of cancers in the future.