Synthesis,Optimization And Characterization Of Paclitaxel-loaded PLGA Porous Microspheres For Cancer Therapy

Background:Chinese medicine is one of the important strategies for cancer therapy,which can not only improve clinical symptoms advantage with few side effects and avoid recurrence,but also prolong the patient's survival and immunity.Paclitaxel(PTX)is a widely used anticancer drug in clinic.It is the main active ingredient of Taxus chinensis.However,the clinical application of paclitaxel often leads to adverse reactions,which greatly limits the application of paclitaxel.Therefore,the development of new formulations of paclitaxel is important.Poly(lactic-co-glycolic acid)(PLGA)is composed of two monomers(LA)-lactic acid and glycolic acid(GA),which is a kind of biodegradable polymers.It has been approved by FDA as a pharmaceutical excipient.Now it is widely used in the fields of pharmaceuticals and medical materials.If the PLGA was combined with paclitaxel,it would be to solve the practical problems,such as poor water solubility and allergic reaction.Purpose:Paclitaxel was used as a model drug to be loaded into PLGA porous microspheres using double emulsion solvent evaporation method(water-oil-water multiple-emulsion-solvent evaporation method).BSA was used as a pore forming agent.The properties of PLGA porous microspheres can be optimized by regulating the content of BSA,the ratio of PLGA to LA/GA,the molecular weight and the type of solvent.In addition,the ability of PLGA to form porous films in 12 different organic solvents was studied,which could provide a new method for preparation of PLGA microspheres.Finally,cell experiments in vitro and tumor bearing mice model in vivo were tested to evaluate the drug release property and tumor inhibition effect of PTX-loaded PLGA microspheres.Method:Chapter 1 Preparation of blank PLGA porous microspheresThe blank PLGA porous microspheres were prepared with double emulsion solvent evaporation method.The effects of BSA content,PLGA molecular weight and the ratio of LA/GA on the diameter and pore size of the microspheres were investigated.The scanning electron microscopy(SEM)was used to observe the surface morphologies of the microspheres to optimize the diameter and pure size of microsphere.Chapter 2 Preparation of PLGA porous thin films in different solventsThe PLGA abilities of forming porous in different organic solvents were carried out,which provided a new method to form the porous structure through the evaporating process of solvent.Chapter 3 Preparation of paclitaxel-loaded PLGA porous microspheres and in vitro antitumor studies.According to the results of the above parts,we prepared paclitaxel-loaded PLGA porous microspheres.The drug loading and encapsulation efficiency of microspheres were tested,and the release behavior of PTX-loaded PLGA porous microspheres in vitro was also evaluated.The slow release properties of paclitaxel-loaded PLGA microspheres were obtained.Analysis of the existing form of drug in the microspheres was proved by DSC,FTIR and XRD antitumor activity of MTT microspheres in vitro.The anti-tumor efficacy of PTX-loaded PLGA porous microspheres was evaluated in CT26 and A549 cells.Chapter 4 In vivo antitumor activity studies of paclitaxel loaded PLGA porous microspheresTo establish a model of tumor bearing mice and to investigate the antitumor effect of paclitaxel loaded PLGA porous microspheres in vivo.Results:Chapter 1:The diameter range of the porous microspheres obtained in our experiments was 6-12 ?m,the most microspheres were 8-10 ?m,and the pore size was in the range of 0.1-0.4 ?m.With the increase of BS A concentration,the molecular weight of PLGA and the ratio of LA/G A,the pore size and particle diameter of PLGA porous microspheres were also increased.Chapter 2:The pore forming properties of PLGA films were investigated in 12 different kinds of organic solvents.The results showed that when the PLGA mass concentration was 10%and the evaporating temperature was 25? the perfect PLGA porous thin film could be obtained in acetonitrile.Chapter 3:In different dosing ratio and BSA concentrations of the paclitaxel loaded PLGA porous microspheres(PTX@PLGA)were prepared.When the dosage of drug loaded porous microspheres was 10:1,the drug loading was 6.40±0.26%,the loading efficiency was 67.5±0.18%;When the dosage of drug loaded porous microspheres was 10:3,the drug loading was 13.74±0.21%,the loading efficiency was 51.10±0.15%.The PTX was gradually released from PTX@PLGA over 9-10 days.The results of XRD,TG and FTIR showed that PTX was successfully encapsulated in PLGA porous microspheres.The results of MTT showed that the concentration of paclitaxel-loaded PLGA porous microspheres with different concentrations had a significant inhibitory effect on A549 and CT26 cells in the final concentration of 4-8 mg/mL.Chapter 4:CT26 tumor bearing mice model showed that 15 mg/kg treatment group could significantly inhibit the growth of tumor in mice after treating with PTX@PLGA.Compared with the model group,the tumor volume of PTX@PLGA 15 mg/kg and 25 mg/kg treatment group and PTX 15 mg/kg mice were decreased,but the tumor volume of the treatment group was smaller than that of the PTX group after 21 days.In addition,the tumor volume of PTX@PLGA group(15 mg/kg)was smaller than that of 25 mg/kg group,which indicated that PTX@PLGA 15mg/kg was the better concentration for inhibiting tumor growth of CT26 tumor bearing mice.Each group had no significant effect on the body weight of mice,which indicated that PTX@PLGA had no obvious side effects.