title: Synthesis of hollow-structured nano- and microspheres from pectin in a nanodroplet emulsion.
abstract: Hollow-structured nano- and microspheres with diameters ranging from 24 microm to 160 nm were successfully produced from chemically modified pectin (Ma-Pec) through a two-step synthesis. In a first step, the Pec was modified with glycidyl methacrylate (GMA) in a heterogeneous phase system, indeed consisting of water-soluble Pec and water-insoluble GMA, via an interfacial reaction at the interface of the GMA-water phase system after 12 h under continuous stirring of 1000 rpm at 60 degrees C. In a second step, the spheres were prepared in a water-in-benzyl alcohol nanodroplet emulsion at 12000 rpm under a bubbling stream of nitrogen in the presence of sodium persulfate, as initiator, and TEMED, as catalytic agent. FT-IR spectra revealed that the vinyl groups (CC) coming from the GMA were attached onto backbone of the polysaccharide. 13C-CP/MAS NMR spectra demonstrated that the spheres were formed via carbon-carbon pi-bonds on Ma-Pec in the water phase, for the duration of the dispersion stage. The dark center (an empty core) and edge of the hollow spheres could be easily identified by SEM micrographs. This type of polymer structure represents a class of unique material with particular importance in terms of state-of the-art applications in both nano- and microencapsulation of drugs, for example, protection shields of biologically active agents.
authors.affiliation: Departamento de Sistemas Quimicos e Informatica DESQ, Faculdade de Engenharia Quimica, Universidade Estadual de Campinas, Zeferino Vaz 13081-970, Campinas, SP, Brazil.
authors.forename: Adriano V
authors.initials: AV
authors.lastname: Reis
authors.forename: Marcos R
authors.initials: MR
authors.lastname: Guilherme
authors.forename: Alexandre T
authors.initials: AT
authors.lastname: Paulino
authors.forename: Edvani C
authors.initials: EC
authors.lastname: Muniz
authors.forename: Luiz H C
authors.initials: LH
authors.lastname: Mattoso
authors.forename: Elias B
authors.initials: EB
authors.lastname: Tambourgi
mesh_terms: D004655:Emulsions / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D008958:Models, Molecular; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010368:Pectins / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D004655:Emulsions; D010368:Pectins