Synthesis, Characterization And Drug Release Study Of Temperature-sensitive PCL-PEG-PCL Hydrogel

In this paper, a series of thermo-sensitive PCL-PEG-PCL triblock copolymers withdifferent PEG and PCL block lengths were synthesized via ring-opening polymerization ofε-CL using PEG10000/PEG20000as the initiator and Sn(Oct)2as the catalys. Thermo-sensitivehydrogels with PCL-PEG-PCL triblock copolymers were prepared. The optimal formingconditions were studied.The molecular weight, composition and structure of the triblock copolymers werecharacterized via1H-NMR、DSC and FT-IR techniques. The Sol-gel transition temperaturewas determined with the test tube inverting method. From the result of the TEM photographs,the shape and structure of the PCL-PEG-PCL copolymer micelles were characterized, and theresult showed that the micells had spherical structures and uniform particle sizes.Based on the blank hydrogel, water-soluble drug with small molecule5-fluorouracil(5-Fu) and water-insoluble drug daidzein (DZ) as model drugs were entrapped into thehydrogel to investigate the drug release characteristics of the gel. The release behavior of5-Fuand DZ from hydrogel related to the drug loading rate and the components of the hydrogel.The drug release curve equation was fitted to study the drug release mechanisms.Finally, the in vivo gel formation and degradation studies indicated that PCL-PEG-PCLcopolymers hydrogels can sustain at least30d by subcutaneous implant and subcutaneousinjection into mice.