Figure 2: Synthesis of PLGA-PEG coated by Iron oxide nanoparticles. The initial structure of Nanomagnets is prepared using an improved chemical coprecipitation method29. According to this method, FeCl2.4H2O and FeCl3.6H2O are dissolved in deionized water and stirred under nitrogen atmosphere at 80°C for 1 hour. Then, NH3.H2O is rapidly injected. After cooling in the room temperature, the precipitated particles are washed and separated by magnetic decantation, and are dried under vacuum at 70°C. In next step, PLGA-PEG is prepared according to the ring opening polymerization method [42,43]. Briefly, Lactide, glycolide and PEG are mixed in three necked bottle under nitrogen atmosphere at 1400°C. Then stannous octoate (0.05% w/w) are added. The solution is stirred under nitrogen atmosphere at 1400°C for 8 hours. After cooling at room temperature, the mixture is dissolved in dichloromethane. Finally, the solution is precipitated in the cold chloroform.