title: pH-responsive poly(methacrylic acid)-grafted hollow silica vesicles.
abstract: Poly(methacrylic acid)-grafted hollow silica vesicles (PMAA-g-hollow silica vesicles) were obtained through a grafting-from approach. PMAA brushes were formed by performing atom-transfer radical polymerisation of sodium methacrylate with an initiator attached to the hollow silica spheres. PMAA-g-hollow silica vesicles were characterised by using TEM, thermogravimetric analysis (TGA) and FTIR spectroscopy. pH-dependent ξ potential and (1)H NMR spectra of PMAA-g-hollow silica vesicles were measured, and the results indicated that MAA brushes in PMAA-g-hollow silica vesicles had a lower ionisation degree and low solubility in acidic aqueous solution, for example, pH 3.4, but a higher ionisation degree and high solubility when the pH was higher than 7. Also it was demonstrated that calcein blue and fluorescein isothiocyanate (FITC) labelled dextran (M(n):10 kDa) could be encapsulated in the interiors of the PMAA-g-hollow silica vesicles with a negligible amount in PMAA brushes at pH 2, and pH-triggered release of calcein blue and FITC-labelled dextran from PMAA-g-hollow silica vesicles was observed at pH 7.4.
authors.affiliation: Institution of Materials Research and Engineering, 3 Research Link, Singapore 117602.
authors.forename: Chee Leng
authors.initials: CL
authors.lastname: Lay
authors.forename: Hui Ru
authors.initials: HR
authors.lastname: Tan
authors.forename: Xuehong
authors.initials: X
authors.lastname: Lu
authors.forename: Ye
authors.initials: Y
authors.lastname: Liu
mesh_terms: D003911:Dextrans / Q000737:chemistry; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D012995:Solubility; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D003911:Dextrans; D011109:Polymethacrylic Acids; D012996:Solutions; D014867:Water; C030613:polymethacrylic acid; D012822:Silicon Dioxide; D016650:Fluorescein-5-isothiocyanate