Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, PR China.
J Biomater Sci Polym Ed. 2011;22(4-6):557-76. doi: 10.1163/092050610X487891.
A novel route was proposed to design and construct a magnetic composite microsphere consisting of Fe(3)O(4) nanoparticles chemically-covalently encapsulated with pH-smart poly(methacrylic acid-co-N-vinyl pyrrolidone) (P(MAA-co-NVP)) cross-linked co-polymers by a surface-initiated radical dispersion polymerization route. The multistep surface treatment was employed to improve the dispersity and surface-chemical reactivity of Fe(3)O(4) nanoparticles, involving introduction of active -NH(2) groups, coupling of 1,1-methylene bis-(4-isocyanato-cyclohexane) and immobilization of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl) propionamide]. The structure and morphological characterization was carried out by FT-IR, TEM, SEM and XRD. The chemically covalent interactions were investigated by FT-IR, TEM, TGA and DSC. The neat Fe(3)O(4) nanoparticles took on an aggregated spherical shape with an average diameter of about 12 nm, while Fe(3)O(4)/P(MAA-co-NVP) magnetic microspheres assumed controllable and monodispersed spheres with a mean dimension of ca. 0.8 μm. The microspheres exhibited superparamagnetic properties. The in vitro caffeine release behavior under varying pH environment was investigated to evaluate the potential of Fe(3)O(4)/P(MAA-co-NVP) magnetic microspheres as a magnetic drug targeting carrier. The results indicated that the microspheres have a faster drug-release rate at pH 7.4 than at pH 1.4, corresponding to their pH swelling. The kinetic modeling demonstrated that the drug release is controlled by a balance between co-polymer chain relaxation and Fickian diffusion process, and the proposed carrier is suitable for a magnetic targeting drug-delivery system.
提出了一种新的途径，通过表面引发的自由基分散聚合方法，设计并构建了一种由 Fe(3)O(4)纳米粒子化学共价封装在 pH 响应性聚（甲基丙烯酸-co-N-乙烯基吡咯烷酮）（P（MAA-co-NVP））交联共聚物中的磁性复合微球。采用多步表面处理方法提高 Fe(3)O(4)纳米粒子的分散性和表面化学反应性，包括引入活性-NH(2)基团、偶联 1,1-亚甲基双（4-异氰酸根合环己烷）和固定 2,2'-偶氮双[2-甲基-N-(2-羟乙基)丙酰胺]。通过 FT-IR、TEM、SEM 和 XRD 进行结构和形态表征。通过 FT-IR、TEM、TGA 和 DSC 研究化学共价相互作用。纯 Fe(3)O(4)纳米粒子呈团聚的球形，平均直径约为 12nm，而 Fe(3)O(4)/P(MAA-co-NVP)磁性微球呈可控制和单分散的球形，平均尺寸约为 0.8μm。微球表现出超顺磁性。研究了在不同 pH 环境下的咖啡因释放行为，以评估 Fe(3)O(4)/P(MAA-co-NVP)磁性微球作为磁性药物靶向载体的潜力。结果表明，微球在 pH 7.4 下的药物释放速率比在 pH 1.4 下快，这与它们的 pH 溶胀相对应。动力学模型表明，药物释放是共聚物链松弛和菲克扩散过程之间平衡的结果，所提出的载体适合用于磁性靶向药物传递系统。
