Synthesis And Characterization Of Y Type Amphiphilic Block Copolymers And Their Stereocomplex Copolymers

In recent years,more and more people are suffering from cancer and it is becoming the major threaten for people health.Nowadays,chemotherapy is the main method for treatment of cancer.However,most of the current chemotherapy drugs exsit too much disadvantages,such as poor solubility,shorter retention time and severe side effects.In this way,they are often limited benefit to the cancer patients.In order to improve the therapeutic effect and the quality of cancer patients' life,a great quantity of work has done.It is discovered that drug-loaded polymeric nanoparticles could improve drug solubility,prolong circulation time,raise accumulation in the tumor sites by the enhanced permeability and retention(EPR)effect and reduce drug side effects.Thus,it is becoming a hotspot to design and prepare polymeric nanoparticles.In this thesis,we synthesized a series of Y type biocompatible amphiphilic block copolymers.Details are as follows:(1)Biocompatible amphiphilic block copolymers PLA-b-PDMAEMA and their stereocomplex micelles(SCMs)were designed and prepared to use for efficient anticancer drugs delivery.The PLA-b-PDMAEMA copolymers were successfully synthesized by ring-opening polymerization(ROP)and atom transfer radical polymerization(ATRP).The structure and composition of these copolymers were characterized by 1H nuclear magnetic resonance(1HNMR)spectroscopy and gel permeation chromatography(GPC).The self-assembly behavior of the copolymers and their stereocomplex copolymers was investigated by fluorescence(FL),dynamic light scattering(DLS),transmission electron microscope(TEM)and zeta potential.It is shown that the SCMs have lower critical micelle concentration(CMC),smaller nanoparticle size compared to the either of the copolymers.Differential scanning calorimetry(DSC)result revealed that the stereocomplex copolymers were successfully prepared by an easy way.In addition,it also displayed that the stereocomplex copolymers have enhancd stability.Moreover,the drug release ability was evaluated by encapusing doxorubicin into the micelles and the SCMS.It was found that the SCMS.have slower release behavior,which caused by the stereocomplex interaction.Additionaly,these copolymers demonstrated good biocompatibility.Therefore,the stereocomplex copolymers are expected to emerge as promising stable nanocarriers for various drugs delivery.(2)Y type PDLA-CD copolymer was prepared by click reaction.The structure and composition of this copolymer was characterized by1 H nuclear magnetic resonance(1HNMR)spectroscopy and gel permeation chromatography(GPC).And then,it was mixed with PLLA-b-PDMAEMA produced in(1)to form stereocomplex copolymers and the self-assemble behavior was investigated.Just like the phenomenon in the part one,the SCMs have lower CMC,smaller size,enhanced stability and good biocompatibility.Thus,there is great potential for this stereocomplex copolymers using as nanocarriers to form anticancer drugs delivery system.