Chitosan as a Lipid Binder: A Langmuir Monolayer Study of Chitosan−Lipid Interactions

Abstract

Owing to its distinct chemico-biological properties, chitosan, a cationic biopolymer, offers a great potential in multifarious bioapplications. One such application is as a dietary antilipidemic supplement to be used to reduce obesity/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 fatty acids, the latter including saturated (stearic acid) and unsaturated (oleic, linoleic, alpha-linolenic) acids. The experiments were performed with the Langmuir monolayer technique, in which surface pressure-area isotherms were recorded for 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 by changes of the molecular organization of the monolayers. The common feature of these changes was that all the monolayers 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 unsaturated fatty acids, linoleic and alpha-linolenic, the lowest for stearic acid, with oleic acid and cholesterol being the intermediate cases. By contrast, the main distinguishing feature of these changes was that, although none of the monolayers studied changed its state when completely saturated with chitosan, compared to the parent ones the compactness of the monolayers was modified. The solid monolayers of stearic acid and cholesterol were loosened, whereas those of all the unsaturated acids, liquid in nature, were tightened. On the basis of these results we tentatively propose a mechanism of the chitosan action that includes both electrostatic and hydrophobic lipid-chitosan interactions as well as hydrogen bonding between them.

Chitosan does not inhibit enzymatic action of human pancreatic lipase in Langmuir monolayers of 1,2-didecanoyl-glycerol (DDG)

“…Accordingly, the resulting surface pressure-area isotherm for this higher chitosan concentration is more expanded. This ability of chitosan to expand DDG monolayers is consistent with the literature, for such expansion has been observed for several surfactants, including lipids or phospholipids such as stearic acid, oleic acid, linoleic acid, ␣-linoleic acid, cholesterol, dipalmitoylphosphatidylglycerol (DPPG), dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidic acid (DMPA) [42][43][44][49][50][51]. The maximum C S −1 (C S −1 max ) can be used to characterize the surface packing of the monolayers [60].…”

“…The maximum C S −1 (C S −1 max ) can be used to characterize the surface packing of the monolayers [60]. [42,43,50,51]. In order to understand the molecular-level interactions between chitosan and DDG, PM-IRRAS experiments were carried out.…”

“…Two main representative phospholipids used were phosphatidylglycerol and phosphatidylcholine to mimic bacterial and mammalian membranes [46][47][48], respectively. Other components employed in monolayers included stearic acid and cholesterol [49][50][51]. From these studies, one can infer that the positively charged chitosans interact more strongly with negatively charged phospholipids, though hydrophobic interactions also play an important role [52,53].…”

Cis-2-decenoic Acid Inhibits S. aureus Growth and Biofilm In Vitro: A Pilot Study

“…Local delivery overcomes some of these obstacles, but diffusion-controlled release of C2DA may require high initial loading concentrations within a drug delivery device, which may cause damage to tissue. Chitosan has lipid binding properties [48], which may give this biomaterial an advantage over other drug delivery devices for controlled delivery of C2DA. The primary disadvantage of many local drug delivery systems has been initial burst release and limited extended release characteristics [32,35].…”

Highly Response and Sensitivity Chitosan-Polyvinyl alcohol Based Hexanal Sensors

“…On the other hand, shrimps, lobster, crabs or krills were exoskeleton creatures that have chitin, one of the most plentiful renewable organic resources in nature. Derivation of chitin will produce polyaminosaccharide compound that also known as chitosan [6]. Chitosan was second most abundant polymer in nature after cellulose.…”