Synthesis Of Glycyrrhetinic Acid Modified PEI-PLGA Copolymers And Its Property As Nanocarrier

Polymer nanoparticles are solid colloidal particles consisting of polymer materials. Polymer nanoparticles have stable morphology, surface effect, small size effect and quantum tunnel effect. Some of them also have specific functions of the temperature, p H, electric field and magnetic field effects. Therefore, polymer nanoparticles have attracted widespread attention. Many chemotherapy drugs possess disadvantages of poor targeting effect and high toxicity. The use of some chemotherapy drugs is restricted because of their poor solubility. Loading of insoluble chemotherapy drugs into nanoparticles not only increases the solubility of drugs, but also impacts targeting effect of drugs to the lesion and reduces the side effect of drugs to normal tissues and cells. Polymer nanoparticles have wide prospects.In this study, biocompatible and biodegradable PLGA was selected as hydrophobic chain and PEI was selected as hydrophilic chain. Amphiphilic PEI-PLGA(PP) copolymers were synthesized through the formation of amide bond. Then PP copolymers were modified by glycyrrhetinic acid to obtain liver targeting GA-PEI-PLGA(GPP) copolymers. Influence of the molar ratios of GA, PEI, PLGA on the formation of GPP nanoparticles was investigated and obtain the optimal molar ratio of 1:1:1. FT-IR, 13C-NMR and 1H-NMR were used to identify the structures of the products, which confirmed the successful sythesis of GPP copolymers. The critical micelle concentration(CMC) of GPP copolymers was determined by the steady-state fluorescence probe method using pyrene as probe. The CMC of GPP copolymers was 21.72 μg/m L. The GPP nanoparticles were spherical and uniform, with average diameter of 164.6 nm and zeta potential of 45 m V. In order to evaluate their safety, the blood compatibility of GPP nanoparticles was studied by hemolysis test. The results showed that the blood compatibility of GPP nanoparticles was better than PP nano- particles. The blood compatibility of PP nanoparticles was better than PEI.Curcumin(Cur) was used as model drug, curcumin loaded GA-PEI-PLGA(Cur/GPP) nanoparticles were prepared by thin film hydration method. The single factor experiment and orthogonal design test were used to investigate the influence of hydration temperature, hydration time and drug amount on the encapsulation efficiency and drug loading of nanoparticles so as to optimize the process. The results indicated that the effect of hydration temperature on encapsulation efficiency and drug loading was maximum, followed by drug amount and hydration time. The optimal preparation conditions were as follows: hydration temperature of 60 ℃, hydration time of 4 h and drug amount of 7 mg. The encapsulation efficiency and drug loading of Cur/GPP nanoparticles were 85.4% and 16.1%, respectively. The transmission electron microscope showed that Cur/GPP nanoparticles were spherical, uniform. The average particle size and zeta potential of Cur/GPP nanoparticles were 330.3 nm and 39.2 m V, respectively. The in vitro release of Cur/GPP nanoparticles was investigated by dynamic dialysis method. The results showed that Cur released quickly and the cumulative release rate reached 95.0% at 3 h. The Cur/GPP nanoparticles had a certain burst release within 2 h. The drug release rate of Cur/GPP nanoparticles increased rapidly from 2 h to 14 h, and increased slowly from 14 h to 86 h. The cumulative release rate at 2h, 14 h and 86 h were 35.4%, 70.4% and 87.0%, respectively. Cur/GPP nanoparticles had sustained release property.The cytotoxicity of GPP nanoparticles and inhibitory effect of Cur/GPP nanoparticles on Hep G2 and BEL-7402 were investigated by MTT test, and compared with Cur/PP nanoparticles and free Cur. The results showed that GPP nanoparticles and PP nanoparticles had inhibitory effect on the growth of Hep G2 and BEL-7402 cells. With the increase of nanoparticles concentration and incubation time, the inhibitory effect and cytotoxicity increased. The inhibitory effect of GPP nanoparticles on the growth of Hep G2 and BEL-7402 cells was lower than PP nanoparticles, which indicated that the cytotoxicity of GPP nanoparticles was lower than PP nanoparticles. After being incubated for 24 and 72 h, the inhibitory rate of Cur/GPP nanoparticles on Hep G2 cell and BEL-7402 cell were higher than Cur/PP nanoparticles and both of them were higher than that of free Cur. After being incubated for 48 h, the inhibitory effect of Cur/PP nanoparticles at lower concentration was higher than that of Cur/GPP nanoparticles, the inhibitory effect of Cur/GPP nanoparticles at higher concentration was higher than that of Cur/PP nanoparticles, and both of them were higher than that of free Cur.The targeting effect of Cur/GPP nanoparticles was evaluated through the cell uptake test. The uptake of Cur/GPP nanoparticles by Hep G2 was observed by confocal laser scanning microscope, and compared with Cur/PP nanoparticles. The results showed that the cell uptake of PP nanoparticles was significantly improved after modification by GA. The uptake of Cur/GPP nanoparticles by Hep G2 cells was much easier and more than Cur/PP nanoparticles,and more Cur/GPP nanoparticles were uptaked into the cell nucleus..