Study On Synthesis Of Dendronized Polycaprolactone And Preparation Of Its Drug-loading Microsphere

Polyester dendrimers/dendrons with excellent biocompatibility is the one and only biodegradable dendrimer which has shown high potential in controlled drug delivery system and tissue engineerring.Divergent synthetic method has been applied in this study to synthesis the first-fourth generation macro-initiator polyethylene glycol terminated by polyester dendrons with different amounts of hydroxyl groups and the dendronized polymers based on these micro-initiators have also been investigated.A series of well-defined dumbbell-shaped tri-block copolymers consisting of comb-like polycaprolactone(PCL)and linear poly(ethylene glycol)(PEG)with narrow molecular weight distributions and varied PCL arm lengths have been synthesized via the sequential preparation of terminal dendronized polyhydric PEG and ring-opening polymerization of(?)-caprolactone(CL).The dendrons and productions were characterized by FT-IR,NMR,GPC,X-ray,DSC and TGA.And the results showed that the melting point and the crystallization temperature shifted to lower temperature with the increasing of branching degree when that series of copolymers had the same molecule weight,but the Tg of copolymers first increased within a narrow range and then decreased by a wide margin.When other series of copolymers had the same branching degree,the melting point?Tg and crystallization temperature shifted to a higher temperature with the increasing of molecule weights of copolymers.The copolymer microsphere was prepared by double emulsion method,,and the effect of preparation process on surface morphology,size and drug loading was studied.The drug loading of temozolomide dendronized polycaprolactone microsphere is 9.01%and the in vitro control release time is more than 27 days.