| Poly(ethylene glycol) cholesterol ester( Me-PEG-chol )was systhesized using succinic anhydride as a spacer, DCC(Dicyclohexyl carbodiimide) and DMAP((N, N'-Dimethyl aminopyridine)as dehydration catalyst. Poly(ethylene glycol) stearate was synthesized in the same way directly from poly(ethylene glycol) and steric acid. The product was examined by means of FT-IR spectra and NMR spectra.. The results indicate that this synthesis method has many advantages,such as mild reactive condition, simple operation, and good degradation property of creative ester bond. This method is favorible in laboratory synthesis.Me-PEG-ch/Me-PEG-st mixed micellar solutions of defferent molar ratio were prepared through solvent vapouring method using THF as an organic solvent. Critical micellization behavior was studied by surface tension measurement. The result showed that after introducing of Me-PEG-chol into Me-PEG-st aquous solution, the CMC value of the system decreased remarkablely comparative to each sigle system. When the molar ratio of Me-PEG-chol and Me-PEG-st was 0.2, the micellar system was the most stable. Similar to the phenomena of cholesterol's stabe function in some biomembrane. Embedding of hydrophobic cholesterol of Me-PEG-chol molecule into fatty layer of Me-PEG-st molecule is the reason of the forming of stable mixed micellar system.The results of dynamic light scattering measurement and TEM observation indicated that the mixed systems form micelles in the size of 10nm with a spherical morphology. The fluorescent probe technique with pyrene as a probe molecule and a drug model as well was used to investigate primary drug delivering behavior of the system. It was found that hydrophobic substance could effectively enrich into the hydrophobic core of mixed micelles, which proved its application as a drug carrier.
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