Spigen Synthesis Lab Report

2.2.1 Preparation of sPEG from polyoxyethylene (20) sorbitanmonolaurate (tween-20)
Star shaped polyoxyethylene (sPEG) was synthesized according to the literature with some changes [18]. Briefly, 8 g of polyoxyethylene (20) sorbitan monostearatev were dissolved in 20 ml of THF in a round bottom flask and then 1 g of KOH was added as hydrolysis agent. After refluxing about 24 h, the solution was concentrated and added to a mixture of acidic water/hexane (1 : 1). The aqueous phase in which the sPEG is dissolved was separated by a separation funnel from hexane. Next, the aqueous phase was neutralized with HCl and extracted with dichloromethane. In order to ensure the purification of the sPEG, this process was repeated further three times with yield 86%.

2.2.2. Preparation of carboxyl terminated star shaped PEG (HO-sPEG-(COOH)3)
The reaction procedure was done according to the reported literature [18]. Briefly, a solution containing 0.3 gr (3 mmol) succinic anhydride and 0.4 ml (3 mmol) of triethylamine in 10 ml of THF was dropwise added to a stirred solution of 1 mmol of sPEG in 10 ml of anhydrous THF for 12 h at 75 C. The solvent of product solution was evaporated by a rotary evaporator and the obtained dark yellow viscous liquid was dissolved in acidic water (pH= 3). In the following,

Fe3O4 nanoparticles were synthesized according to our previously reported method by chemical co-precipitation of Fe2+ and Fe3+ ions with a molar ratio of 1:2 [19]. Briefly, 2.4 g of FeCl3.6H2O and 0.8 g of FeCl2.4H2O were dissolved in 30 mL of deionized water under using continuous N2 purge at 70 °C. and Under vigorous stirring, followed by dropwise addition of 10 mL of NH3.H2O was dropwise added to the reaction mixture until the color of mixture turned to black and kept reacting for 90 min to complete the reaction. At the end, the synthesized Fe3O4 nanoparticles were separated by a magnet and washed by using water and ethanol for further three times with 89.3%