Development of Fe3O4-poly(l-lactide) magnetic microparticles in supercritical CO2

The Fe₃O₄-poly(l-lactide) (Fe₃O₄-PLLA) magnetic microparticles were successfully prepared in a process of solution-enhanced dispersion by supercritical CO₂ (SEDS), and their morphology, particle size, magnetic mass content, surface atom distribution and magnetic properties were characterized. Indomethacin (Indo) was used as a drug model to produce drug-polymer magnetic composite microparticles. The resulting Fe₃O₄-PLLA microparticles with mean size of 803 nm had good magnetic property and a saturation magnetization of 24.99 emu/g. The X-ray photoelectron spectroscopy (XPS) test indicated that most of the Fe₃O₄ were encapsulated by PLLA, which indicated that the Fe₃O₄-PLLA magnetic microparticles had a core–shell structure. After further loading with drug, the Indo-Fe₃O₄-PLLA microparticles had a bigger mean size of 901 nm, and the Fourier transform infrared spectrometer (FTIR) analysis demonstrated that the SEDS process was a typical physical coating process to produce drug-polymer magnetic composite microparticles, which is favorable for drugs since there is no change in chemistry. The in vitro cytotoxicity test showed that the Fe₃O₄-PLLA magnetic microparticles had no cytotoxicity and were biocompatible, which means there is potential for biomedical application.