Studies On The Preparation Of Drug-loaded Sustained-release Janus PLGA Microspheres And Induction Of Cell Apoptosis

Poly(lactic-co-glycolic acid)(PLGA)is widely used as drug carriers because of its good biological compatibility and biodegradability.Nanoprecipitation is a commonly used method of preparing PLGA particles.Compared with other preparation methods,nanoprecipitation has the features of simple experimental procedure,easy operation,mild reaction conditions and low energy consumption.Microfluidic technology has unique advantages in preparing multifunctional particles.It can not only control the morphology,size and monodispersity of particles,but also has the characteristics of less reagent consumption,less environmental pollution and so on.In this paper,we combined microfluidic technology with nanoprecipitation for preparing submicron Janus PLGA microspheres.Two anti-cancer drugs simultaneously were loaded in the hemispheres of Janus PLGA microspheres,and HeLa cell apoptosis induced by them was investigated.In chapter one,the preparation of Janus particles and the application of Janus particles in biological analysis and biomedical fields were reviewed firstly.And then PLGA particles and their application in biological field were introduced.After that,the development of nanoprecipitation methods and preparation of PLGA nanoparticles using microfluidic platform were presented.Finally,the purpose and design of this work were proposed.In chapter two,submicron Janus PLGA microspheres were successfully prepared by combining microfluidic technology with nanoprecipitation.Janus PLGA microspheres with smaller size and better morphology were fabricated by optimizing the flow rate ratios of two phases,the concentration of PLGA and the channel width.And also the effects of solvent and anti-solvent phases on the morphology of particles were investigated.Biphasic Janus PLGA microspheres were characterized by adding two different fluorescent dyes into the two hemispheres using the inverted fluorescence microscope and the confocal laser scanning microscopy.In chapter three,paclitaxel and doxorubicin were respectively loaded to the biphasic Janus PLGA microspheres,and cumulative release rates of paclitaxel and doxorubicin in PBS were tested,which were 86%and 21%respectively.Action of drug-loaded Janus PLGA microspheres on HeLa cells was investigated.When two anti-cancer drugs were simultaneously loaded into Janus PLGA microspheres,the apoptosis rate of HeLa cells is 62%,and when paclitaxel or doxorubicin was loaded alone into microspheres,the apoptosis rate of HeLa cells are 29%and 31%respectively.It is obvious that the synergies of two anti-cancer drugs loaded in Janus microspheres significantly increased the apoptosis rates of HeLa cells.In chapter four,the method of Janus PLGA microsphere preparation was summarized,and the applications of drug-loaded Janus PLGA microspheres were prospected.The Janus particles might be quite promising for combined imaging and targeted therapy.