title: A novel method for the preparation of nanoaggregates of methoxy polyethyleneglycol linked chitosan.
abstract: In the study, methoxy polyethyleneglycol (MPEG) linked chitosan (PLC) with a different degrees of substitution were prepared using a novel yet simple method in the presence of formaldehyde in a solvent of formic acid and dimethylsulfoxide (DMSO). The obtained PLC was verified by the Fourier transformed infrared (FT-IR) and carbon nuclear magnetic resonance (13C-NMR) spectroscopy and by the gel permeation chromatography (GPC). The aqueous solubility of chitosan increased after chemically linking with MPEG and was found to depend on its degree of substitution. With a proper degree of substitution of MPEG on chitosan, PLC may undergo inter- and/or intra-molecular entanglements to produce nanoaggregates. The critical aggregation concentration (CAC) of PLC was determined by the fluorescence emission spectra of pyrene and was found to be 0.003 mg/ml. Measurements of the size distribution and zeta potential of the prepared nanoaggregates were carried out using a Zetasizer. The results suggested that as the degree of MPEG substitution increased, the size and polydispersity index of the prepared nanoaggregates decreased. The prepared nanoaggregates showed a pH-sensitive property and thus may be suitable for the development of drug delivery devices for tumors.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC.
authors.forename: Anandrao R
authors.initials: AR
authors.lastname: Kulkarni
authors.forename: Yu-Hsin
authors.initials: YH
authors.lastname: Lin
authors.forename: Hsiang-Fa
authors.initials: HF
authors.lastname: Liang
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Chang
authors.forename: Wesley Wei-Wen
authors.initials: WW
authors.lastname: Hsiao
authors.forename: Hsing-Wen
authors.initials: HW
authors.lastname: Sung
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D014677:Pharmaceutical Vehicles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances; D014677:Pharmaceutical Vehicles; D011092:Polyethylene Glycols; D048271:Chitosan