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

Stenger, Patrick C.; Isbell, Stephen G.; Zasadzinski, Joseph A.

doi:10.1016/j.bbamem.2008.03.019

Cited by 23 publications

(66 citation statements)

References 54 publications

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“…2 shows fluorescence images of Curosurf and ETS (TSP = 77 mg/m 3 ) exposed Curosurf at 25°C on the second cycle. Discrete black domains coexist in a continuous medium gray background, similar to model lung surfactant lipid-protein mixtures and other commercial lung surfactants [13, 60, 61]. The dark domains are condensed phases (typically semi-crystalline areas enriched in saturated lipids [20, 25, 26, 35]) that exclude the bulky fluorophore-labeled Texas Red-DHPE, which cannot pack into a crystalline lattice [62].…”

Section: Resultsmentioning

confidence: 99%

“…The stated concentrations of Survanta and Curosurf dispersions were deposited dropwise onto the saline buffer subphase (150 mM NaCl, 2 mM CaCl 2 , and 0.2 mM NaHCO 3 , pH = 7) of the Langmuir trough at the stated total surfactant concentrations and allowed to equilibrate 20 minutes before beginning cycling. Surfactant deposited in this fashion adsorbs from the subphase to the interface as multilayer aggregates that convert to a monolayer on contact with the air-water interface [33, 60, 61]. …”

Section: Methodsmentioning

confidence: 99%

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Environmental tobacco smoke effects on lung surfactant film organization

Stenger

Alonso

Zasadzinski

et al. 2009

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Adsorption of the clinical lung surfactants (LS) Curosurf or Survanta from aqueous suspension to the air-water interface progresses from multi-bilayer aggregates through multilayer films to a coexistence between multilayer and monolayer domains. Exposure to environmental tobacco smoke (ETS) alters this progression as shown by Langmuir isotherms, fluorescence microscopy and atomic force microscopy (AFM). After 12 hours of LS exposure to ETS, AFM images of Langmuir-Blodgett deposited films show that ETS reduces the amount of material near the interface and alters how surfactant is removed from the interface during compression. For Curosurf, ETS prevents refining of the film composition during cycling; this leads to higher minimum surface tensions. ETS also changes the morphology of the Curosurf film by reducing the size of condensed phase domains from 8–12 μm to ~ 2μm, suggesting a decrease in the line tension between the domains. The minimum surface tension and morphology of the Survanta film are less impacted by ETS exposure, although the amount of material associated with the film is reduced in a similar way to Curosurf. Fluorescence and mass spectra of Survanta dispersions containing native bovine SP-B treated with ETS indicate the oxidative degradation of protein aromatic amino acid residue side chains. Native bovine SP-C isolated from ETS exposed Survanta had changes in molecular mass consistent with deacylation of the lipoprotein. Fourier Transform Infrared Spectroscopy (FTIR) characterization of the hydrophobic proteins from ETS treated Survanta dispersions show significant changes in the conformation of SP-B and SP-C that correlate with the altered surface activity and morphology of the lipid-protein film.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Environmental tobacco smoke effects on lung surfactant film organization

Stenger

Alonso

Zasadzinski

et al. 2009

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…Da Silva et al [62] have shown that serum proteins leaking into a ventilated rat lung led to significant decreases in surfactant performance and lung compliance; the effects on the surfactant were less when the lung was flushed to remove blood and reduce cholesterol. In vitro , there is an ARDS-like depression of LS activity when serum proteins are added to a LS-covered interface [68–70, 74, 78], LS is added to a serum-covered interface [13, 79–84] or both LS and serum proteins are presented simultaneously [85–87]. …”

Section: Surfactant Inactivationmentioning

confidence: 99%

“…8,10) [79, 80, 82–84, 97] that shows albumin and LS coexist at an air-water interface. As surfactant adsorption increases, the serum proteins must be displaced from the interface; as the surface pressure increases above the serum Π eq , the serum proteins are displaced from the interface and return to the subphase [13, 79, 80, 82–84, 97]. At higher serum concentrations in the subphase, the interfacial density of serum is also higher, and surfactant must displace more protein to adsorb and raise the surface pressure.…”

Section: Equilibrium Vs Kinetic Effectsmentioning

confidence: 99%

Overcoming rapid inactivation of lung surfactant: Analogies between competitive adsorption and colloid stability

Zasadzinski

Stenger

Shieh

et al. 2010

Biochimica et Biophysica Acta (BBA) - Biomembranes

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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. or polyelectrolytes such as chitosan, added to LS, 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.

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“…1a), and its interactions with DPPC are investigated, and the feasibility of using this novel molecule to prevent protein adsorption is evaluated. The mechanism underlying the protein-induced LS dysfunction is thought to involve an energy barrier that is induced by the proteins as a result of their adsorption to the phospholipid monolayer [28]. With its ability to compete with DPPC for fibrinogen adsorption, the unique molecular structure and high adsorption rate of this newly synthesized molecule is proposed to minimize the damage related to protein adsorption.…”

Section: Introductionmentioning

confidence: 99%