|
Amphiphilic block polymer in aqueous solution by self-assembly to form a core - shell structure of the micelles can be used as a drug delivery system. The hydrophobic core of the polymeric micelles for packets contain the hydrophobic drug, a hydrophilic shell to provide a stable protective layer of a solvate, avoid micellar aggregation. In this paper, the ATRP method Synthesis of pH-sensitive amphiphilic block copolymer of poly (methyl methacrylate-co-methacrylic acid)-b-poly methyl acrylate, monomethoxy polyethylene glycol (P (MMA- co-MAA)-b--PPEGMA), and from the mesoscopic level simulation of the formation and morphology of the drug-loaded micelles. Thesis are as follows: the design of pH-sensitive amphiphilic block copolymer molecular structure, P (MMA-co-MAA)-the b-PPEGMA hydrophobic block PMMA and pH-sensitive block random copolymer to form a polymer micelle core for packets contain hydrophobic drugs; the hydrophilic block PPEGMA polymer brush-like structure, help to improve the as micellar housing, micelle shell density, enhanced hydrophilic micelle surface, anti-protein and platelet adsorption capacity, improve micelle stability. ATRP method, 2 - bromo ethyl isobutyrate (EBriB), as initiator and CuBr / N, N, N, N ', N'-pentamethyl diethylene triamine (CuBr / PMDETA) as the catalyst system, the synthesis of the copolymer; determined by gel permeation chromatography (GPC), proton nuclear magnetic resonance spectroscopy (1H NMR) and infrared spectroscopy (FT-IR) characterize the structures of the polymer to give a molecular weight of 10344, a molecular weight Distribution of the low polymer. Fluorescent probe measurement of the polymer critical micelle concentration of 1.3 mg / L. Dissipative particle dynamics (DPD) and mesoscopic dynamics (MesoDyn), simulation of the formation process of the P (MMA-co-MAA)-b-PPEGMA drug-loaded micelles in aqueous solution, as well as system components formula hydrophobic block ratio, pH change on micelle formation and morphology. Ibuprofen as a model drug. The DPD simulations show that the formation process of the drug-loaded system can be divided into three stages: (1) each component is highly fragmented, P (MMA-co-MAA)-b-PPEGMA began to gather phase; (2) drug molecules to the polymer aggregates internal spread of drug-loaded micelle formation stage; (3) micellar stabilization phase. Polymer block composed of recipes and the pH value will affect the micelle formation and morphology. Lower proportion of hydrophobic block, the drug-loaded micelles nucleation difficulties, and the formation of micelles there are more defects;-part formulation changes in the drug-loaded micelles showed spherical, cylindrical and lamellar structure; pH gt; 5, the pH-sensitive block MAA ionization and the formation of micellar structures irregular and loose, and is conducive to the release of the drug. The in vitro release results also show that, at pH 1.2 when the slow rate of drug release, and 24 h only 17% released; at pH 7.4, the rate of drug release is significantly accelerated, 24 h has been completely released. Computer simulation methods to study the impact of structural changes on the drug system performance from the mesoscopic level, which auxiliary guidance polymer molecules and drug micelle structure design.
|