Interaction between cholesterol and chitosan in Langmuir monolayers

Abstract

Chitosan incorporated in the aqueous subphase is found to affect the Langmuir monolayers of cholesterol, causing the surface pressure and the surface potential isotherms to become more expanded. The mean molecular area per cholesterol molecule in the condensed monolayer increases from 53 Ų in the absence of chitosan to 61 Ų for a concentration of 0.100 mg/mL of chitosan in the subphase. If additional chitosan is incorporated in the subphase, no change is noted, which points to saturation in the effects from chitosan. The interaction between chitosan and cholesterol probably occurs via hydrogen bonding. The monolayer expansion is also manifested in the monolayer morphology, as indicated by Brewster angle microscopy measurements, where larger cholesterol domains are visualized when chitosan is present in the subphase

Interactions of bioactive molecules & nanomaterials with Langmuir monolayers as cell membrane models

“…chitosan in pioneering work by Fang and co-workers, where a very low chitosan concentration was used (0,008-0,024 mg/mL) [98], it has been subsequently shown by different groups that chitosan always expands lipid monolayers of different compositions (glycerol-, choline-and phosphatidic acid-based phospholipids; cholesterol, stearic, oleic or linoleic acid lipids) [99][100][101][102][103][104][105][106][107][108][109][110]. Such expansion is usually accompanied by a reduction in the film in-plane elasticity, which is a manifestation of chitosan incorporation into the interface.…”

“…Although counter-intuitive since monolayer expansion usually occurs at the expense of a decrease in film packing, this is explained by the physical presence at the interface of the macromolecule, which squeezes lipids and restricts those molecules to a smaller actual area. Remarkably, a peculiar feature of the modulation of film properties imposed by chitosan (especially expansion and decrease of elasticity) is the existence, in most cases, of a saturation concentration [99][100][101][102][103], which commonly lies between 0.1 and 0.3 mg/mL. A saturation concentration is relevant since it suggests the existence of an ideal chitosan dose to be administered in real biological applications.…”

“…In terms of interaction forces, there has been speculation since earlier studies [99,100,103]that electrostatic, hydrogen bonding and hydrophobic interactions are involved in chitosan adsorption to lipid monolayers. Moreover, as chitosan is a positively charged polymer, charge-mediated interactions are presumed to be the predominant contribution.…”

Efeito de características estruturais da quitosana sobre sua interação com filmes de Langmuir como modelo de biomembrana

“…Isso se deve, especialmente, à falta de atividade superficial do polissacarídeo (62) . Em trabalhos de nosso grupo (7,8,63,64) , observou-se que a quitosana pode ter atividade superficial induzida por monocamadas de lipídios, seja com colesterol (63) ou fosfolipídios neutros e carregados negativamente (7,8) . Essa atividade superficial induzida pelas moléculas de lipídios aponta para fortes interações entre os materiais, que podem ser responsáveis por algumas propriedades da quitosana.…”

Interação entre quitosana e modelos de membrana celular: filmes de Langmuir e Langmuir-Blodgett (LB)

“…No já citado trabalho de Gargallo e colaboradores, filmes de um copolímero alternado de anidrido malêico e estearil metacrilato foram empregados (84). Apenas outros quatro trabalhos, um de nosso grupo e outros três de grupos de Cingapura, México e Polônia, usaram filmes de Langmuir de moléculas biológicas e exploraram a interação com quitosana, em estudos semelhantes ao desta tese de doutorado (88)(89)…”