title: Mesoscopic simulations on the aggregation behavior of pH-responsive polymeric micelles for drug delivery.
abstract: Computer simulations, dissipative particle dynamics (DPD) and mesoscopic dynamics (MesoDyn), are performed to study the aggregation behavior of pH-sensitive micelles self-assembled from amphiphilic polymer poly(methyl methacrylate-co-methacrylic acid)-b-poly(poly-(ethylene glycol) methyl ether monomethacrylate), P(MMA-co-MAA)-b-PPEGMA. Ibuprofen (IBU) is selected as the model drug. It can be seen from DPD simulations that P(MMA-co-MAA)-b-PPEGMA and IBU form spherical core-shell micelles at certain compositions, and IBU molecules distribute inside the core formed by hydrophobic MMA. The polymer molecules aggregate first, and then IBU diffuses into the aggregate, forming drug-loaded nanoparticles. With different compositions of polymer and IBU, aggregate morphologies in water are observed as sphere, column and lamella. From MesoDyn results, with less hydrophobic MMA beads, the polymer chains are more difficult to form ordered aggregates, and the order parameters get equilibrated in a longer time. The pH value also affects the aggregate process. At pH<5, the polymer could form traditional core-shell micelles. But at pH>5, the morphology of micelles is found to be anomalous and loose for releasing drug. MAA aggregates on the surface, instead of the inside. The simulation results are qualitatively consistent with the experimental results.
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Ling Shan
authors.initials: LS
authors.lastname: Zheng
authors.forename: You Qiang
authors.initials: YQ
authors.lastname: Yang
authors.forename: Xin Dong
authors.initials: XD
authors.lastname: Guo
authors.forename: Yao
authors.initials: Y
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Qian
authors.forename: Li Juan
authors.initials: LJ
authors.lastname: Zhang
mesh_terms: D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors
chemical_list: D008823:Micelles; D011108:Polymers