Interaction between chitosan and bovine lung extract surfactants.
The interaction between a cationic polyelectrolyte, chitosan, and an exogenous bovine lung extract surfactant (BLES) was studied using dynamic compression/expansion cycles of dilute BLES preparations in a Constrained Sessile Drop (CSD) device equipped with an environmental chamber conditioned at 37 degrees C and 100% R.H. air. Under these conditions, dilute BLES preparations tend to produce variable and relatively high minimum surface tensions. Upon addition of "low" chitosan to BLES ratios, the minimum surface tension of BLES-chitosan preparations were consistently low (i.e. <5 mJ/m2), and the resulting surfactant monolayers (adsorbed at the air-water interface) were highly elastic and stable. However, the use of "high" chitosan to BLES ratios induced the collapse of the surfactant monolayer at high minimum surface tensions (i.e. >15 mJ/m2). The zeta potential of the lung surfactant aggregates in the subphase suggests that chitosan binds to the anionic lipids (phosphatidyl glycerols) in BLES, and that this binding is ultimately responsible for the changes in the surface activity (elasticity and stability) of these surfactant-polyelectrolyte mixtures. Furthermore the transition from "low" to "high" chitosan to BLES ratios correlates with the flocculation and de-flocculation of surfactant aggregates in the subphase. It is proposed that the aggregation/segregation of "patches" of anionic lipids in the surfactant monolayer produced at different chitosan to BLES ratios explains the enhancing/inhibitory effects of chitosan. These observations highlight the importance of electrostatic interactions in lung surfactant systems.
Kang
Ningxi
N
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON, Canada M5S 3E5.
Policova
Zdenka
Z
Bankian
Gelareh
G
Hair
Michael L
ML
Zuo
Yi Y
YY
Neumann
A Wilhelm
AW
Acosta
Edgar J
EJ
D000388:Air; D000818:Animals; D002417:Cattle; D048271:Chitosan / Q000378:metabolism*; D019245:Compressive Strength; D004548:Elasticity; D006863:Hydrogen-Ion Concentration; D011663:Pulmonary Surfactants / Q000378:metabolism*; D014020:Tissue Extracts / Q000378:metabolism*
D011663:Pulmonary Surfactants; D014020:Tissue Extracts; D048271:Chitosan