Dataset Information

Molecular weight dependence of the depletion attraction and its effects on the competitive adsorption of lung surfactant.

ABSTRACT: Albumin competes with lung surfactant for the air-water interface, resulting in decreased surfactant adsorption and increased surface tension. Polyethylene glycol (PEG) and other hydrophilic polymers restore the normal rate of surfactant adsorption to the interface, which re-establishes low surface tensions on compression. PEG does so by generating an entropic depletion attraction between the surfactant aggregates and interface, reducing the energy barrier to adsorption imposed by the albumin. For a fixed composition of 10 g/L (1% wt.), surfactant adsorption increases with the 0.1 power of PEG molecular weight from 6 kDa-35 kDa as predicted by simple excluded volume models of the depletion attraction. The range of the depletion attraction for PEG with a molecular weight below 6 kDa is less than the dimensions of albumin and there is no effect on surfactant adsorption. PEG greater than 35 kDa reaches the overlap concentration at 1% wt. resulting in both decreased depletion attraction and decreased surfactant adsorption. Fluorescence images reveal that the depletion attraction causes the surfactant to break through the albumin film at the air-water interface to spread as a monolayer. During this transition, there is a coexistence of immiscible albumin and surfactant domains. Surface pressures well above the normal equilibrium surface pressure of albumin are necessary to force the albumin from the interface during film compression.

SUBMITTER: Stenger PC

PROVIDER: S-EPMC2575753 | biostudies-literature | 2008 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Molecular weight dependence of the depletion attraction and its effects on the competitive adsorption of lung surfactant.

Stenger Patrick C PC Isbell Stephen G SG Zasadzinski Joseph A JA

Biochimica et biophysica acta 20080403 10

Albumin competes with lung surfactant for the air-water interface, resulting in decreased surfactant adsorption and increased surface tension. Polyethylene glycol (PEG) and other hydrophilic polymers restore the normal rate of surfactant adsorption to the interface, which re-establishes low surface tensions on compression. PEG does so by generating an entropic depletion attraction between the surfactant aggregates and interface, reducing the energy barrier to adsorption imposed by the albumin. F ...[more]

PMID: 18433716

Similar Datasets

Project description:Lung surfactant (LS) is a mixture of lipids and proteins that line the alveolar air-liquid interface, lowering the interfacial tension to levels that make breathing possible. In acute respiratory distress syndrome (ARDS), inactivation of LS is believed to play an important role in the development and severity of the disease. This review examines the competitive adsorption of LS and surface-active contaminants, such as serum proteins, present in the alveolar fluids of ARDS patients, and how this competitive adsorption can cause normal amounts of otherwise normal LS to be ineffective in lowering the interfacial tension. LS and serum proteins compete for the air-water interface when both are present in solution either in the alveolar fluids or in a Langmuir trough. Equilibrium favors LS as it has the lower equilibrium surface pressure, but the smaller proteins are kinetically favored over multi-micron LS bilayer aggregates by faster diffusion. If albumin reaches the interface, it creates an energy barrier to subsequent LS adsorption that slows or prevents the adsorption of the necessary amounts of LS required to lower surface tension. This process can be understood in terms of classic colloid stability theory in which an energy barrier to diffusion stabilizes colloidal suspensions against aggregation. This analogy provides qualitative and quantitative predictions regarding the origin of surfactant inactivation. An important corollary is that any additive that promotes colloid coagulation, such as increased electrolyte concentration, multivalent ions, hydrophilic non-adsorbing polymers such as PEG, dextran, etc. added to LS, or polyelectrolytes such as chitosan, also promotes LS adsorption in the presence of serum proteins and helps reverse surfactant inactivation. The theory provides quantitative tools to determine the optimal concentration of these additives and suggests that multiple additives may have a synergistic effect. A variety of physical and chemical techniques including isotherms, fluorescence microscopy, electron microscopy and X-ray diffraction show that LS adsorption is enhanced by this mechanism without substantially altering the structure or properties of the LS monolayer.

Dataset Information

Molecular weight dependence of the depletion attraction and its effects on the competitive adsorption of lung surfactant.

Publications

Molecular weight dependence of the depletion attraction and its effects on the competitive adsorption of lung surfactant.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets