title: Novel polymer-layered silicate intercalated composite beads for drug delivery.
abstract: Core-shell structured beads were fabricated from chitosan (CS)/organic rectorite (OREC) composites and alginate (ALG) in Ca(2+) aqueous solutions with different mixing ratios by a cross-linking process. The mechanical properties, surface and internal morphology, intercalation structure between CS and OREC, porosity and pore size distribution, bovine serum albumin (BSA) encapsulation efficiency and its controllable release ability were investigated. Optical microscopy, scanning electron microscopy and transmission electron microscopy showed that the core-shell structure was generated in the beads. The Fourier transform infrared spectra results implied the presence of electrostatic and hydrogen-bonding interaction between CS and OREC. The energy-dispersive X-ray and X-ray photoelectron spectroscopy results verified the existence of OREC in the beads. Small-angle X-ray diffraction results confirmed that the interlayer of OREC was intercalated by CS chains successfully, and the interlayer distance increased from 2.42 to 2.60 nm. The BSA encapsulation and release test indicated that the beads released the drug continuously. OREC could not only avoid the burst release phenomenon in the first period but also improve the utilization efficacy of the drug. When the ratio of CS/OREC was 6:1 and CS-OREC/ALG was 2:1, the beads were better for drug released in stomach, and when CS/OREC was 12:1 and CS-OREC/ALG was 2:1, the beads were better for drug released in stomach than in intestine.
authors.affiliation: a Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology, Xi'an Jiaotong University , Xi'an, P. R. China.
authors.forename: Ruifen
authors.initials: R
authors.lastname: Xu
authors.forename: Xuyang
authors.initials: X
authors.lastname: Feng
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Shangjing
authors.initials: S
authors.lastname: Xin
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Wang
authors.forename: Hongbing
authors.initials: H
authors.lastname: Deng
authors.forename: Lixian
authors.initials: L
authors.lastname: Xu
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000538:Aluminum Silicates / Q000737:chemistry*; D000818:Animals; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D048271:Chitosan / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006244:Hardness; D006603:Hexuronic Acids / Q000737:chemistry; D008903:Minerals / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D012710:Serum Albumin, Bovine / Q000008:administration & dosage
chemical_list: D000464:Alginates; D000538:Aluminum Silicates; D003432:Cross-Linking Reagents; D004337:Drug Carriers; D006603:Hexuronic Acids; D008903:Minerals; C546376:rectorite; D012710:Serum Albumin, Bovine; D020723:Glucuronic Acid; D048271:Chitosan; D002118:Calcium