Preparation And Drug Controlled Release Of Amphiphilic Thermo-Sensitive Triblock Copolymer Containing Poly(N-isopropylacrylamide)

In the drug delivery system,in order to improve the bioavailability of drugs,drug carriers need to possess both targeting and stimulating response characteristics.Therefore,it is desirable to design micelles of stimulated response-type block copolymers as a controlled drug delivery vehicle to release the drug in a controlled manner after they reach the target site.In this dissertation,we mainly use the methods of ring-opening polymerization(ROP)and atom transfer radical polymerization(ATRP)to synthesize the temperature-sensitive triblock polymers mPEG-b-PLA-b-PNIPAM and mPEG-b-PNIPAM-b-PLA,both of which can self-assemble into stable micelles in aqueous solution.Among the two temperature-sensitive triblock polymers,the properties of triblock polymers mPEG-b-PNIPAM-g-PLA micelles were mainly studied.Adriamycin(DOX)was used as a model drug to study the drug loading and release behavior.As the experimental results suggest,the ATRP technique provides the possibility of tuning the lower critical solution temperatures(LCST)of the polymer easily by changing composition of EG,NIPAM and L-LA.In addition,the drug loading rate and entrapment efficiency of mPEG24-b-PNIPAM96-b-PLA55 polymer micelles were the highest at 15.65% and 23.14%,respectively,and the drug release rate at 37 °C was much higher than that at 25 °C.In summary,the triblock polymer mPEG22-b-PNIPAM96-b-PLA55 has excellent properties as a drug carrier.