Synthesis And Characterization Of CMOSA Modified PLA/PEG/PLA Copolymer And Its Application In Drug Delivery System

In this article, a series of amphiphilic triblock copolymers PLA/PEG/PLA with different molecular weights were synthesized through ring-opening polymerization of lactide and polyethylene glycol in the presence of stannous octoate as catalyst. Ternary carboxylic acid CMOSA was adopted to modify copolymer PLA/PEG/PLA (1) to obtain carboxyl terminated copolymer (2). The copolymer was characterized via 1H-NMR, IR, and GPC. The results indicate that the esterification degree of CMOSA and PLA/PEG/PLA was more than 62%, and the molecular weight is of little change after molecular modification.Select sodium salicylate (SS), o-phenanthroline (OPH) and TED as model drugs, the drug encapsulation rate and control-release behaviour of copolymers were studied. The morphology of the micelles was observed via TEM and the size was tested via dynamic light scattering. The results indicate that, the micelles prepared through double emulsion method have larger size and lower CMC than that prepared through single emulsion, and have a clear core-shell structure. Carboxyl terminated copolymer (2) had higher drug encapsulation rate and better control-release behaviour than that of copolymer (1), and has a good ability in co-release of SS/TED. We also studied the drug release behaviour of sodium salicylate and tetrandrine in microparticles and the interaction between carrier and drug was studied via DSC. The morphology of the microparticles was observed via SEM. Results indicate that copolymer (2) microparticles can improve the drug encapsulation rates and have a mild release behaviour in the whole stage. Carboxyl terminated copolymer microparticles have larger size, and the surface is porous because of the hydrophilic carboxyl end groups.Introduce TED-loaded micelle solution into chitosan/gelatine system to obtain porous 3D scaffold through freeze-drying. The morphology and size distribution of the pores were observed via SEM, mechanical properties were tested by stress test. The results indicated that the scaffold combined with micelles is of better porosity and permeability, and can strengthen the scaffold toughness. And the release behaviour of TED indicates that it can control the release of TED effectively.