Preparation Of Chitosan-modified Drug-loaded PLGA Nanoparticles By High Gravity Method

Poly(lactic-co-glycolic acid)(PLGA)are well recognized an ideal drug carrier material due to good biocompatibility and biodegradability.Therefore,PLGA has been widely used in the field of biomedicine.However,there are some shortcomings of PLGA in practical application such as non-targeting,negative surface which is not conducive to cell uptake and drug burst release.Those disadvantages need to be overcome so that PLGA can be better applied in clinical.Chitosan(CS)could be used to modify the PLGA nanoparticles due to its inherent biocompatibility,positive electricity and mucosal adhesion.High gravity rotating bed(RPB)has become one of the most advanced process intensification equipment because of its high mass transfer and mixing efficiency.In this paper,CS was selected to modify PLGA nanoparticles and one-step preparation of CS-modified PLGA nanoparticles by RPB was carried out.The antitumor properties of CS-modified PLGA nanoparticles were also studied.The main research contents are as follows:(1)PLGA nanoparticles with uniform particle size and rounded morphology were prepared by RPB nanoprecipitation method using acetone as solvent and water as antisolvent.The effects of RPB cycle time,RPB rotational speed,PLGA concentration,surfactant concentration and solvent-to-antisolvent ratio on the particle size of PLGA nanoparticles were investigated.The optimum technological conditions are as follows:RPB speed is 1000 r/min,PLGA concentration is 5 mg/mL,surfactant concentration is 0.03 mg/mL,solvent-antisolvent ratio is 1:20.Compared with the PLGA nanoparticles prepared under the optimum conditions in beaker(130.6+3.8 nm),the average particle size of PLGA nanoparticles prepared by RPB(122.7+2.2 nm)is smaller and the particle size distribution is more concentrated.(2)The effects of CS modification on the average particle size,surface potential,drug loading,entrapment efficiency and drug release in vitro of PLGA microspheres were investigated.The pH-responsiveness of PLGA nanoparticles was also studied.The results show that with the increase of CS content,the average particle size increases gradually,and the zeta potential changes from negative to positive.Compared with PTX-PLGA nanoparticles,the encapsulation efficiency of PTX-CS-PLGA nanoparticles(CS/PLGA=0.2,CS/PLGA=0.4,CS/PLGA=0.8)increased gradually.The cumulative release of PTX from PTX-CS-PLGA nanoparticles decreased with the increase of CS modification after 2 hours.In addition,PTX-CS-PLGA nanoparticles showed pH-responsiveness.The release rate of PTX under pH 5.5 was significantly higher than that under pH 7.4.(3)MDA-MB-231 cells were used as model cells to investigate the antitumor activity of CS-modified PLGA nanoparticles in vitro.The results showed that neither CS nor PLGA had cytotoxicity.Modification of PLGA nanoparticles by CS can enhance the antitumor activity because that CS-modified PLGA nanoparticles could enter into cells through endocytosis.The greater the modification of PLGA nanoparticles by CS,the stronger the antitumor activity of CS on tumor cells.Drug loaded PLGA nanoparticles can enter the cytoplasm,but cannot enter the nucleus.However,CS-modified PLGA nanoparticles can not only enter cells,but also enter the nucleus.As the increase of modification amount of CS,CS-modified PLGA nanoparticles can enter the nucleus more effectively.