Optimized Preparation Of PH-responsive Polymeric Nanoparticles And Investigation Of Their Controlled Drug Release

Objective: To obtain the optimal preparation process of pH-responsive polymer nanoparticles and to investigate the drug-controlled release behavior of doxorubicin-loaded polymer nanoparticles in cells.Method: Polylactic acid-glycolic acid copolymer(PLGA)was used as shell material,anticancer drug doxorubicin was used as model drug,sodium bicarbonate was used as p H response factor,and pH-responsive PLGA nanoparticles were prepared by diffusion solvent evaporation method.The single process method was used to investigate the main process conditions(concentration and weight average molecular weight of PLGA,concentration of sodium bicarbonate,concentration of soy lecithin,concentration of polyvinyl alcohol(PVA),concentration of natural water-soluble vitamin E(TPGS))The effects of average particle size,particle size distribution index(PDI)and encapsulation efficiency of nanoparticles were investigated.The morphology of nanoparticles was characterized by scanning electron microscopy(SEM).The drug release of pH-responsive PLGA nanoparticles under different p H conditions(p H=7.4,6.0 and 4.0)in vitro was investigated.The coumarin-6 was used to mark the green fluorescence of the nano-shell material,and the doxorubicin itself showed red fluorescence.The fluorescence-responsive confocal microscopy(Confocal)was used to investigate the pH-dependent drug release behavior of the nanoparticles in breast cancer cells.Results: 1.The particle size increases with the increase of PLGA content and its weight average molecular weight,and the particle size distribution decreases first and then increases.The encapsulation efficiency increases first and then decreases,which is optimal at 50 mg and 10.5w.The distribution of the lecithin increased first and then decreased with the increase of lecithin content.The encapsulation efficiency increased first and then decreased at 40 mg.The particle size continued to increase with the increase of PVA concentration,and the particle size distribution decreased first and then increased.It is the best at 0.2%;the increase of particle size TPGS increases first,then increases and then increases,the particle size distribution decreases first and then increases,the encapsulation rate increases first and then decreases,which is the best at 0.03%;particle size and distribution With the increase of Na HCO3 concentration,the decrease firstly increases and then decreases.The encapsulation efficiency increases first and then decreases,which is better at 2.5 mg/ml and 5 mg/ml.The TPGS and PVA are the external aqueous phase diffusion phase zeta potential of-31.11 m V,respectively.-25.54 m V.In summary,the optimum process parameters for the nanoparticles are 50 mg of PLGA having a weight average molecular weight of 10.5 w,40 mg of lecithin,0.03%of TPGS,and an internal aqueous phase containing 2.5 mg/ml or 5 mg/ml of Na HCO3.2.The in vitro drug release of the prepared nanoparticles was p H dependent,and the drug release rate increased with the decrease of p H;in the acidic medium with p H=4,the drug release rate of 24 hours was close to 100%.The results of intracellular drug release showed that the nanoparticles entered the breast cancer cells in co-culture for 0.5 hours;when reached for 6 hours,there was strong red fluorescence in the nucleus,and the nanoparticles around the nucleus showed green fluorescence.Conclusion: The pH-responsive nanoparticle prepared by the optimized process has an average particle size of 115-130 nm and an entrapment efficiency of more than 65%.It can enter cancer cells through endocytosis and rapidly release the drug into the nucleus via an acidic organelle to kill cancer cells.