Chitosan as a Lipid Binder: A Langmuir Monolayer Study of Chitosan-Lipid Interactions
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- 作者：Pawe<img src="http ; //pubs.acs.org/images/entities/lstrok.gif" border="0"> Wydro ; Barbara Krajewska ; Katarzyna H<img src="http ; //pubs.acs.org/images/entities/acedil.gif" border="0">c-Wydro
- 刊名：Biomacromolecules
- 出版年：2007
- 出版时间：August 2007
- 年：2007
- 卷：8
- 期：8
- 页码：2611 - 2617
- 全文大小：135K
- 年卷期：v.8,no.8(August 2007)
- ISSN：1526-4602
文摘
Owing to its distinct chemico-biological properties, chitosan, a cationic biopolymer, offers a great potential inmultifarious bioapplications. One such application is as a dietary antilipidemic supplement to be used to reduceobesity/overweight and to lower cholesterol. The lipid-binding efficiency of chitosan, however, remains debatable.Accordingly, in this study we investigated the interactions of chitosan with selected lipids, cholesterol and fattyacids, the latter including saturated (stearic acid) and unsaturated (oleic, linoleic, <IMG SRC="/images/gifchars/alpha.gif" BORDER=0>-linolenic) acids. The experimentswere performed with the Langmuir monolayer technique, in which surface pressure-area isotherms were recordedfor the lipid monolayers spread on the acetate buffer pH 4.0 subphase in the absence and presence of chitosan.We found that the presence of chitosan in the subphase strongly influenced the shape and location of the isotherms,proving that there existed attractions between chitosan and lipid molecules. The attractions were revealed bychanges of the molecular organization of the monolayers. The common feature of these changes was that all themonolayers studied underwent expansion, in each case reaching saturation with increasing chitosan concentration.In agreement with the lipid molecular structures, the highest expansions were observed for the most unsaturatedfatty acids, linoleic and 
-linolenic, the lowest for stearic acid, with oleic acid and cholesterol being the intermediatecases. By contrast, the main distinguishing feature of these changes was that, although none of the monolayersstudied changed its state when completely saturated with chitosan, compared to the parent ones the compactnessof the monolayers was modified. The solid monolayers of stearic acid and cholesterol were loosened, whereasthose of all the unsaturated acids, liquid in nature, were tightened. On the basis of these results we tentativelypropose a mechanism of the chitosan action that includes both electrostatic and hydrophobic lipid-chitosaninteractions as well as hydrogen bonding between them.
-linolenic, the lowest for stearic acid, with oleic acid and cholesterol being the intermediatecases. By contrast, the main distinguishing feature of these changes was that, although none of the monolayersstudied changed its state when completely saturated with chitosan, compared to the parent ones the compactnessof the monolayers was modified. The solid monolayers of stearic acid and cholesterol were loosened, whereasthose of all the unsaturated acids, liquid in nature, were tightened. On the basis of these results we tentativelypropose a mechanism of the chitosan action that includes both electrostatic and hydrophobic lipid-chitosaninteractions as well as hydrogen bonding between them.