title: Synthesis and application of poly(ethylene glycol)-cholesterol (Chol-PEGm) conjugates in physicochemical characterization of nonionic surfactant vesicles.
abstract: Vesicles possessing poly(ethylene glycol) (PEG) chains on their surface have been described as a blood-persistent drug delivery system with potential applications for intravenous drug administration. In this research with different molecular weights (400-10,000g/mol) of PEG, a series of Chol-PEG(m) conjugates were generated by the DCC (N,N'-dicyclohexylcarbodiimide, DCC)/(4-dimethylaminopyridine, 4-DMAP) esterification method, and confirmed by FT-IR and (1)H NMR spectrum. Then their properties in aqueous solution were studied by electron microscopy images, associative behavioral and systematic tensiometric studies over a wide concentration range. In order to elucidate the application of this Chol-PEG(m) in vesicles, conventional nonionic surfactant vesicles (niosomes) composed of span 60 and cholesterol were prepared and the influence of various hydrophilic chains of the Chol-PEG(m) conjugates was investigated. Results indicated that all the niosomes prepared, with or without Chol-PEG(m) composition were similar in micrograph with diameter between 120 nm and 180 nm. The fixed aqueous layer thickness (FALT) around niosomes increased as Chol-PEG(m) chain length increase, particularly in the Chol-PEG(10,000) modified niosomes with 9.33+/-0.67 nm. In vitro release experiments indicated that release rate of nimodipine from Chol-PEG(m) modified niosomes was enhanced. Chol-PEG(m) modified niosomes showed greater accumulative release than that of plain niosomes over a period of 24 h. These studies have shed some light on the suitability of Chol-PEG(m) containing niosome preparation.
authors.affiliation: Pharmaceutical Research Institute, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, PR China.
authors.forename: Dan-bo
authors.initials: DB
authors.lastname: Yang
authors.forename: Jia-bi
authors.initials: JB
authors.lastname: Zhu
authors.forename: Zhang-jian
authors.initials: ZJ
authors.lastname: Huang
authors.forename: Hai-xia
authors.initials: HX
authors.lastname: Ren
authors.forename: Zeng-juan
authors.initials: ZJ
authors.lastname: Zheng
mesh_terms: D002784:Cholesterol / Q000138:chemical synthesis / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D012212:Rheology; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity
chemical_list: D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D002784:Cholesterol