Study On The Controllable Preparation And Self-assembly Mechanism Of Polymersomes

Polymer vesicles,also known as polymersomes,which are based on the self-assembly of amphiphilic block-copolymers(BCPs)in water with the size distribution from nanometer to micrometer scale,have attracted great interest in biomedical field(such as artificial cells,bioreactors and drug delivery).There are various requirements or factors need to be elucidated for the promising applications,such as size distribution,morphological structure,stability and functionality.The understanding to the application of polymersomes as drug carriers(drug loading/release),as well as exploring the formation process and self-assembly mechanism of the polymersomes are important to this study.The details as follows:(1)To explore the preparation of biocompatible polymersomes under controllable making process.The size distribution and morphology of the polymersomes were affected by many factors such as the characteristics of the amphiphilic BCPs(molecular weight,block ratio and blending ratio),solvent and preparation method.We obtained polymersomes with micron-sized and nano-sized made from biocompatible BCPs with different types and molecular weight distribution.Then we studied the parameters of differences of polymersomes with different block ratio and blending ratio.(2)To study the preparation of p H-responsive polymersomes.In this chapter,we choose a p H-responsive diblock copolymer,a poly(2-methacryloyloxy ethyl phosphorylcholine)-bpoly[2-(diisopropylamino)ethyl methacrylate](PMPC-b-PDPA),as a model object for the preparation of polymer vesicles by film hydration,solvent evaporation and p H switch(titration)methods.The characteristics of polymersomes via the three methods were investigated.It was found that the vesicles prepared by p H switch method show some virtues: uniform scale size,excellent dispersivity,and adjustable self-assembly time,which is convenient for the applications as drug delivery carriers.The results shown that,as a drug delivery,the p H-responsive polymersomes provide a promising way in drug-delivery and disease treatment.(3)To explore the self-assembly mechanism of p H-responsive polymersomes.In this chapter,on basis of preliminary studies on the controllable preparation of p H-responsive vesicles via the p H switch(titration)method,we using Small Angle X-ray Scattering(SAXS),Transmission Electron Microscopy(TEM)and Dynamic Light Scattering(DLS)to characterize and monitor variation of the aggregates during the self-assembly process of p H-responsive vesicles.The formation mechanism of polymersomes was elucidateed based on the results.