Preparation And Characterization Of Magnetic Polylactic Acid Microspheres

Magnetic Polymer Microspheres (MPM) are a kind of novel functional materials, which behave properties of magnetic materials and polymer materials.The formulation and application of hybrid microspheres composed of polymeric and magnetic material are of great interest for biomedical applications, especially in cell separation, purity of protein, nucleic acid separation, immobilized enzyme and magnetically targeted drug delivery systems, etc. Polymeric material is wrapped in the surface of magnetic particles. The kind of amino acid polymer such as albumin, glutin and the kind of amylose polymer such as starch, chitosan are extensively applied as the wrapping materials at present. Polylactic acid (PLA) has extensively been used as an implant biomedical material due to its good biocompatibility. However, it is rarely used as a material to wrap magnetic particles. The present study is to tentatively research to use polylactic acid as the polymeric materials to wrap magnetic particles. The preparation technics and influence parameter were discussed especially in the study.The Fe₃O₄ magnetic particles were prepared by co-precipitation method. FeCl₂·4H₂O and FeCl₃·4H₂O were used as raw materials. The NH₃·H₂O was used to adjust the pH value of the system while oleic acid was used as stabilizer. Nano Fe₃O₄ particles were obtained when process parameters were well controlled. The polylactic acid magnetic microspheres were then fabricated using solvent evaporation method. An optimum-formatting experiment was designed to analyze the different factors such as molecular weight, content of PLA, quantity of emulsifier (polyvinyl alcohol), the type and content of oil phase and the percentage of Fe₃O₄/PLA. Their effects on size and morphology of microspheres together with the property of magnetic response were discussed.The magnetic microspheres were characterized through Zetasizer 3000-HSA Laser Granularity instrument, X-ray diffraction (XRD), Transmission Election Microscope (TEM), Scanning Tunneling Microscope (SEM). The results show that nano-Fe₃O₄ magnetic particles could be obtained through the co-precipitation method. The particles are sized in 20-100 microns. The magnetic microspheres performed high magnetic response, which entitled it for drug carrying, especially for targeting drug delivery systems.