title: Fabrication and caffeine release from Fe3O4/P(MAA-co-NVP) magnetic microspheres with controllable core-shell architecture.
abstract: 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.
authors.affiliation: Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, PR China.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Di
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Luo
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Yao-Shao
authors.initials: YS
authors.lastname: Chen
authors.forename: Yun-Fei
authors.initials: YF
authors.lastname: Nan
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D002110:Caffeine / Q000737:chemistry / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D000697:Central Nervous System Stimulants / Q000737:chemistry / Q000378:metabolism; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008280:Magnetics; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008422:Materials Testing; D008863:Microspheres; D015394:Molecular Structure; D010316:Particle Size; D011109:Polymethacrylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D011760:Pyrrolidinones / Q000138:chemical synthesis / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D000697:Central Nervous System Stimulants; D004337:Drug Carriers; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; D011109:Polymethacrylic Acids; D011760:Pyrrolidinones; D002110:Caffeine; C042670:N-vinyl-2-pyrrolidinone