Synthesis And Properties Of Amphiphilic Copolymers As Drug Carriers

It is well known that amphiphilic polymers consist of hydrophilic part and hydrophobic part in the structure. Due to this unique chemical structure, it can form a core-shell structure of polymer micelles in aqueous medium. The hydrophobic part forms the core and the hydrophilic part forms shell. They have unique advantages in macromolecular drugs, low water-solubility drugs and gene therapy as drug carriers.In order to study the characteristics of amphiphilic polymers and drug-loaded nanoparticles(NPs), we used PAsp and gelatin as hydrophilic segment through copolymerizatinreaction, synthesized amphiphilic poly (L-aspartic acid co-L-lactide) grafted polymer and amphiphilic gelatin-polylactide grafted polymer. Then, we used 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine(DPPE) to synthesize two novel amphiphilic polymers that were poly(L-aspartic acid co-L-lactide)-1,2-dipalmitoyl-sn- glycero-3-phosphoethanolamine and gelatin-polylactide-1,2-dipalmitoyl-sn-glycero-3- phosphorethanolamine. The amphiphilic polymers were characterized by FT-IR and NMR. The fluorescence experiments showed that amphiphilic polymers have a very low critical micelle concentration (CMC).The dynamic light scatter (DLS) and transmission electron microscopy (TEM) experiments indicated that the nanoparticles had uniform particle size and were apt to a spherical shape.To understand the molecular interaction mechanism of inclusion complex between amphiphilic polymers and the medicine, Doxorubicin hydrochloride(DOX), cyclosporin A(CsA) and paclitaxel (PTX) were chosen as model drug to study their vitro drug release behavior from nanoparticles. Drug-loaded nanoparticles were prepared by nanoprecipitation, double emulsion and emulsification solvent evaporation methods, respectively. Different factors which influence on particular size,encapsulation efficiency(EE) and drug-loaded content(LC) were investigated, and in vitro released characteristics were investigated by ultraviolet spectrum(UV) or high performance liquid chromatography (HPLC). We studied the cytotoxicity of the DOX-loaded NPs and PTX-loaded NPs. The results showed that the ability of killer cells of the drug-loaded nanoparticles was proportional to the concentration, the drug-loaded nanoparticles was the same on killer cells withthe drugs.