In this study, different molecular weight CM-chitosans were prepared and the effects on the growth and collagen secretion of normal skin fibroblasts and keloid fibroblasts were investigated in vitro. CM-chitosan promoted the proliferation of the normal skin fibroblast significantly but inhibited the proliferation of keloid fibroblast. The higher CM-chitosan concentration had a higher initial effect and the lower CM-chitosan concentration had a longer affecting time to the normal skin fibroblast. The lower molecular weight CM-chitosan had significant twofold activities. The CM-chitosan could reduce the ratio of type I/III collagen in keloid fibroblast by inhibiting the secretion of collagen type I; and had no effect on the secretion of types I and III collagen in the normal skin fibroblast. r 2002 Elsevier Science Ltd. All rights reserved.

Membranes were prepared from chitosan with different molecular weights by a casting method. The molecular affinity and permeability of the membranes for sodium chloride, glucose, tyrosine, and bovine serum protein were measured at 4

Chitosan was modified by coupling with linoleic acid through the 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide-mediated reaction to increase its amphipathicity for improved emulsification. The micelle formation of linoleic acid-modified chitosan in the 0.1 M acetic acid solution was enhanced by O/W emulsification with methylene chloride, an oil phase. The fluorescence spectra indicate that without emulsification the self-aggregation of LA-chitosan occurred at the concentration of 1.0 g/L or above, and with emulsification, self-aggregation was greatly enhanced followed by a stable micelle formation at 2.0 g/L. The addition of 1 M sodium chloride promoted the self-aggregation of LA-chitosan molecules both with and without emulsification. The micelles of LA-chitosan formed nanosize particles ranging from 200 to 600 nm. The LA-chitosan nanoparticles encapsulated the lipid soluble model compound, retinal acetate, with 50% efficiency.

Carboxymethyl chitosan (CM-chitosan) was prepared by chemical reaction with monochloroacetic acid under various conditions, and the chemical structure was analyzed by IR and NMR. The water solubility of the CM-chitosans had close relationships to the modifying conditions and the degree of carboxymethylation. The CM-chitosans, prepared at temperatures of 0-10 8C were soluble in water. But the CM-chitosan prepared between 20 and 60 8C were insoluble in the water at near-neutral pH. The water insolubility of CM-chitosans at various pHs varied with the degree of carboxymethylation. The increase in reaction temperature increased the fraction of carboxymethylation and increased the insolubility at lower pHs; the increase of the ratio of water/isopropanol in the reaction solvent decreased the fraction of carboxymethylation and increased the insolubility at higher pHs.

通过玻璃流延法制备不同分子质量的壳聚糖及羧甲基壳聚糖膜，以体外培养的人皮肤成纤维细胞作为对象，利用膜的浸渍液培养及膜表面直接培养法研究比较了两种多糖膜的细胞相容性。实验发现两种多糖膜的浸渍液对细胞均无毒性效应，生物安全性是小分子质量膜好于大分子质量膜，羧甲基壳聚糖膜好于壳聚糖膜。皮肤成纤维细胞在壳聚糖膜上的生长受到抑制，生长一段时间后细胞有聚集和脱落现象，而羧甲基壳聚糖膜上细胞能很好地贴附、生长，没有聚集和脱落现象。结果表明羧甲基壳聚糖膜具有比壳聚糖膜更优越的细胞相容性。