Study Of PLGA Based Magnetic Microspheres

Magnetic microsphere is a new-fashioned targeted drug delivery system, which contains superparamagnetic iron nanoparticles as well as the drug and exhibits superparamagnetic property.Which magnetic field with magnetic, when the external magnetic field disappeared after withdrawal. In the external magnetic field under can be move to the focus area, in the local concentration to achieve the purpose of targeted drug delivery.However, in drug and magnetic microspheres hinge elements, has been the focus of attention of many scholars. Current hinge elements are: Polylactide (PLA), polyglycolid (PGA), polycaprolactone (PCL), PolymethylMethacrylate (PMMA), polystyrene (PS), cellulose, cellulose-polyethylene, poly hydroxy-propyl ester, gelatin and copolymer between them and biological polymer material, such as protein, phospholipids, glucoprotein, liposome, collagen protein such as. What is the hinge which agents for different magnetic microsphere the best there is no clear conclusion. Based on the above, this study is the purpose of preparation of Fe₃O₄ superparamagnetic nanoparticles using chemical coprecipitation method and surface characterization was carried out. And made to PLGA based magnetic microspheres. A preliminary understanding of its bio-safety by in vitro blood compatibility.PART 1 Preparation and characterization of superparamagnetic Fe₃O₄ nanoparticles .Objective: To explore the well conditions of preparation of Fe₃O₄ superparamagnetic nanoparticles using chemical coprecipitation method with Sodium oleate as dispersing agent.Methods:Fe₃O₄ superparamagnetic nanoparticles ware prepared using chemical coprecipitation method. Sodium oleate was used as dispersing agent.Factors such as the amount of sodium oleate and NaOH, reaction temperature, as well as concentration of trivalent iron which had influence on particle formation and stability ware investigated, and the optimized formation was determined. Particle diameter was determined by transmission electron microscope (TEM) and magnetic induction of the particles was recorded by Vibration sample magnetometer. Results:Fe₃O₄ superparamagnetic nanoparticles prepared under 55℃,30 min Crystallization time,0.5 mol/L Trivalent iron and 0.3% sodium oleate had optimized saturation magnetic intensity. The diameter of Fe₃O₄ superparamagnetic nanoparticles distributed between 9nm～25nm.PART 2 Preparation and characterization of PLGA based superparamagnetism nanparticles. Objective: To study the preparation and magnetic targeting performance of PLGA based superparamagnetism nanparticles. Methods:Ultrasound emulsification and high-speed homogenization methods, W / O / W complex emulsion-solvent evaporation synthesis of magnetic PLGA microspheres targeting vector. The magnetic induction of PLGA NPs through the optical microscope. Further scanning electron microscopy, particle size analysis and targeting experiments in vitro. Results: Successfully synthesized mainly the core-shell-like structure of the microspheres into the round ,which particle size 1μm 4μm, with an average particle size of 2.643μm, size distribution of concentration . Targeting experiments in vitro have confirmed that the PLGA NPs has superparamagnetic ability.PART 3 Hemocompatibility of PLGA based superparamagnetism nanparticles and Fe₃O₄ superparamagnetic nanoparticles. Objective: To test the compatibility of PLGA NPs and Fe₃O₄ NPs with blood and blood cells. Methods: The hemocompatibility of PLGA NPs and NPs was evaluated with a particular focus on hemolytic activity, platelet function, and blood coagulation. Human red blood cell lysis was determined by measuring hemoglobin release. Activation and aggregation of human platelets were determined using flow cytometry .Finally; the whole blood clotting time was measured using human blood. Results: PLGA NPs significantly decreased in vitro red blood cell lysis than superparamagnetism Nanparticles.In addition, under conditions tested, PLGA NPs did not activate platelets. In fact, both NPs formulations very rapidly inhibited agonist-induced platelet activation and aggregation in a dose-dependent manner. Additionally, PELA NPs significantly prolonged in vitro whole blood clotting time at a concentration of 500 mg/mL or greater.