title: Synthesis of thiolated chitosan and preparation nanoparticles with sodium alginate for ocular drug delivery.
abstract: OBJECTIVE
  The goal of the present study was to synthesize mucoadhesive polymer - thiolated chitosan (TCS) from chitosan (CS), then prepared CS/TCS-sodium alginate nanoparticles (CS/TCS-SA NPs), determined which was more potential for ocular drug delivery.
  
  
  METHODS
  A new method for preparing TCS was developed, and the characteristics were determined using Fourier transform infrared spectroscopy and the degree of thiol immobilized was measured by Ellman's reagent. Human corneal epithelium (HCE) cells were incubated with different concentrations of TCS for 48 h to determine the cell viabilities. CS/TCS-SA NPs were prepared and optimized by a modified ionic gelation method. The particle sizes, zeta potentials, Scanning electron microscopy images, mucoadhesion, in vitro cell uptake and in vivo studies of the two types of NP were compared.
  
  
  RESULTS
  The new method enabled a high degree of thiol substitution of TCS, up to 1,411.01±4.02 μmol/g. In vitro cytocompatibility results suggest that TCS is nontoxic. Compared to CS-SA NPs, TCS-SA NPs were more stable, with higher mucoadhesive properties and could deliver greater amounts of drugs into HCE cells in vitro and cornea in vivo.
  
  
  CONCLUSIONS
  TCS-SA NPs have better delivery capability, suggesting they have good potential for ocular drug delivery applications.
authors.affiliation: School of Pharmaceutical Science, Xiamen University, Xiamen, China. zhuxuan@xmu.edu.cn
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhu
authors.forename: Meiqin
authors.initials: M
authors.lastname: Su
authors.forename: Shaoheng
authors.initials: S
authors.lastname: Tang
authors.forename: Lingsong
authors.initials: L
authors.lastname: Wang
authors.forename: Xinfang
authors.initials: X
authors.lastname: Liang
authors.forename: Feihong
authors.initials: F
authors.lastname: Meng
authors.forename: Ying
authors.initials: Y
authors.lastname: Hong
authors.forename: Zhiran
authors.initials: Z
authors.lastname: Xu
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D048271:Chitosan / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000494:pharmacology; D004228:Dithionitrobenzoic Acid; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000494:pharmacology; D004355:Drug Stability; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D019573:Epithelium, Corneal / Q000166:cytology / Q000187:drug effects; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D056965:Injections, Intraocular; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000464:Alginates; D004337:Drug Carriers; D006603:Hexuronic Acids; D013438:Sulfhydryl Compounds; D020723:Glucuronic Acid; D048271:Chitosan; D004228:Dithionitrobenzoic Acid