Formation Of Amphiphilic Poly(?-caprolactone) Microcapsules Embedded With Functional Cores And Its Application As Drug Carriers

Poly(?-caprolactone)(PCL) microcapsules,as a type of drug carriers,has advantages in drug storage and delivery.Pristine PCL has a strong hydrophobicity,very slow degradation rate due to its high crystallinity.Effective surfactants play a very important role in traditional double emulsion methods to prepare PCL capsules.However,its potential toxicity should not be neglected.In addition,it is not easy for drugs to be released out from the long-standing PCL capsules.In this article,we try to fix these problems by developing a novel amphiphilic PCL microcapsule embedded with functional cores.So,it is possible to achieve better encapsulation ability and sustained release,based on the new structural design of capsules and the improved hydrophilicity and degradation rate of amphiphilic materials.Firstly,two kinds of PCL derived co-polyesters were successfully synthesized: poly(CL-co-TOSUO)(PCT) is the co-polymerization product of 1,4,8-trioxaspiro-[4,6]-9-undecanone(TOSUO)and ?-caprolactone(CL),mPEG-poly(CL-co-TOSUO)(mPEG-PCT) is the co-polymerization product of methoxy poly(ethylene glycol)(mPEG),TOSUO and CL.Their chemical structures were characterized by a nuclear magnetic resonance(NMR) spectrometer.Depending on the feeding amount of TOSUO and mPEG,the hydrophilicity and degradability of co-polymers can be adjusted.Then we tried to modify the tractional double emulsion method by introducing new components such as natural polysaccharides(including alginate(ALG) and chitosan(CS)),graphene oxide(GO) into inner water phase.The possible interactions existed between polysaccharide/polymer,GO/polymer in the water-oil interface was verified,which proved useful to improve emulsion stability.Based on these progresses,we successfully prepared two types of amphiphic PCL microcapsules embedded with polysaccharide and GO coles,respectively.1.Formation of amphiphilic PCL microcapsules embedded with polysaccharide cores and its application as drug carriersAs two typical polysaccharides,cationic chitosan(CS) and anionic sodium alginate(ALG) were separately employed in this experiment.The primary emulsion was self-stabilized based on interactions between carbohydrate chains and amphiphilic polymer chains which existed in water-oil interface.The effects on emulsion stability,morphology and composition of obtained capsules,drug encapsulation ability and in vitro release profile,were systematically studied by SEM,UV-VIS,FTIR characterizations and rheological tests.When encapsulating doxorubicin hydrochloride,the embedded alginate cores can be used to accommodate drug molecules based on non-covalent interactions.As a result,great improvements of encapsulation ability and sustained release can be achieved simultaneously.2.Preparation of amphiphilic polycaprolactone microcapsules embedded in graphene oxide core and its drug loading propertiesGraphene oxide(GO) was separately employed in this experiment.The primary emulsion was self-stabilized based on interactions between graphene oxide sheet and amphiphilic polymer chains which existed in water-oil interface.The effects of GO,PVA,GO and PVA mixed solutions on the stability of emulsion were studied.The morphology,composition of obtained capsules and drug encapsulation ability were systematically studied by DLS,SEM,UV-VIS,FTIR characterizations and rheological tests.And the effects of polymer types(PCL,PCT,mPEG-PCT),internal water phase types and the volume ratio of oil-water two phases on the microcapsule morphology were studied.When encapsulating doxorubicin hydrochloride,the embedded graphene oxide cores can be used to accommodate drug molecules based on electrostatic interactions.As a result,great improvements of encapsulation ability can be achieved simultaneously.