Preparation and in Vitro Experiment of Attapulgite-based Microgels with Magnetic/Temperature Dual Sensitivities

The folic acid (FA)-grafted magnetic FA-Fe3O4/ATP-P(NIPAM-AAM) composite microgels (attapulgite=ATP, N-isopropyl acrylamide=NIPAM, acrylamide=AAM) were prepared via a method of emulsion copolymerization. The as-prepared microgels were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TG), infrared spectroscopy (IR), UV-visible spectroscopy (UV), scanning electron microscope (SEM) and transmission electron microscope (TEM). The dynamic light scattering (DLS) results show that the low critical solution temperature (LCST) of microgel was about 38.5 degrees C. The drug delivery ability of the as-prepared microgels was evaluated by using doxorubicin hydrochloride (DOX) as the model drug. Based on the drug loading and releasing results, the presence of ATP increased the amount of drug loading and releasing. Compared with free DOX, the in vitro cytotoxicity of DOX loaded FA-Fe3O4/ATP-P(NIPAM-AAM) was decreased and the biocompatibility was improved. Those results indicate that the microgels of FA-Fe3O4/ATP-P(NIPAM-AAM) can be used in potential as a slow-release drug system. The in vitro cellular uptake test revealed that the microgels of FA-Fe3O4/ATP-P(NIPAM-AAM) at the assigned site were significantly richer than that of other sites. This result indicates that the microgels of FA-Fe3O4/ATP-P(NIPAM-AAM) composite are targeting and expectable in the application of targeted drug releasing.