Probing Chitosan and Phospholipid Interactions Using Langmuir and Langmuir−Blodgett Films as Cell Membrane Models

Abstract

The interaction between chitosan and Langmuir and Langmuir-Blodgett (LB) films of dimyristoyl phosphatidic acid (DMPA) is investigated, with the films serving as simplified cell membrane models. At the air-water interface, chitosan modulates the structural properties of DMPA monolayers, causing expansion and decreasing the monolayer elasticity. As the surface pressure increased, some chitosan molecules remained at the interface, but others were expelled. Chitosan could be transferred onto solid supports alongside DMPA using the LB technique, as confirmed by infrared spectroscopy and quartz crystal microbalance measurements. The analysis of sum-frequency vibration spectroscopy data for the LB films combined with surface potential measurements for the monolayers pointed to chitosan inducing the ordering of the DMPA alkyl chains. Furthermore, the morphology of DMPA LB films, studied with atomic force microscopy, was affected significantly by the incorporation of chitosan, with the mixed chitosan-DMPA films displaying considerably higher thickness and roughness, in addition to chitosan aggregates. Because chitosan affected DMPA films even at pressures characteristic of cell membranes, we believe this study may help elucidate the role of chitosan in biological systems.

Interaction of O-acylated chitosans with biomembrane models: Probing the effects from hydrophobic interactions and hydrogen bonding

“…Therefore, hydrophobic forces are likely to play an important role, in accordance with our previous results [25][26][27][28] and with the literature [31,32]. Indeed, Krajewska et al [31,32] have shown that non-electrostatic contributions are relevant for chitosan interaction with DPPC, DPPG and cholesterol monolayers in measurements where pH and temperature changes were studied.…”

“…A comparison of the activities from distinct samples of chitosan indicates, however, that non-electrostatic interactions also play an important role [25,26]. Indeed, the importance of these types of interactions has been demonstrated at the molecular level in studies with model membranes [23,[25][26][27][28][29][30][31][32].…”

“…The latter include the inability to reproduce in vivo conditions for the cell and the use of only a few components of a real cell. Nevertheless, with present technology some types of molecular-level information can only be obtained in membrane models, and therefore several studies have been made with Langmuir monolayers as membrane models [23,[25][26][27][28][29][30][31][32][33].…”

Vibrational spectroscopy for probing molecular-level interactions in organic films mimicking biointerfaces

“…DMPA is one of the most used phospholipids in this context owing to its suitability to deposit multilayers [131,132]. Examples include studies of a mucin protein in LB films of DMPA, where chitosan was able to gradually remove the protein, according to FTIR measurements [116] and interaction studies between DMPA and the protein-polysaccharide complex extracted from the mushroom Agaricus blazei Murill [133].…”

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

“…Incidentally, the Langmuir-Blodgett technique is useful in the study of molecular-level interactions, in addition to allowing for assembling nanomaterials for sensors and optical and electronic devices [40,41]. Chitosan was able to expand and penetrate phospholipid Langmuir monolayers [42][43][44][45]. Two main representative phospholipids used were phosphatidylglycerol and phosphatidylcholine to mimic bacterial and mammalian membranes [46][47][48], respectively.…”