Comparative study of clinical pulmonary surfactants using atomic force microscopy.

Area of Science:

• Biophysics
• Materials Science
• Pulmonary Medicine

Background:

• Clinical pulmonary surfactant is vital for treating respiratory distress syndrome in premature infants.
• Existing research focuses on composition and performance, but lacks direct film structure comparisons.
• Understanding surfactant film structure is crucial for optimizing clinical applications.

Purpose of the Study:

• To characterize and compare the lateral structure of four animal-derived clinical surfactants.
• To compare these surfactants against model synthetic and natural bovine surfactants.
• To elucidate the relationship between structure, composition (DPPC, cholesterol), and surface pressure.

Main Methods:

• Atomic force microscopy (AFM) was employed to visualize and analyze surfactant film structures.
• Four commercially available animal-derived surfactants (Survanta, Curosurf, Infasurf, BLES) were studied.
• Comparisons were made with dipalmitoyl phosphatidylcholine (DPPC), a DPPC:palmitoyl-oleoyl phosphatidylglycerol mixture, and bovine surfactant.

Main Results:

• Atomic force microscopy revealed significant differences in the lateral structure and molecular organization among the surfactant preparations.
• All animal-derived clinical surfactants exhibited a similar multilayer structure with an interfacial monolayer enriched in DPPC.
• Structural differences were correlated with variations in dipalmitoyl phosphatidylcholine and cholesterol content.

Conclusions:

• Animal-derived clinical surfactants share a common structural organization at physiologically relevant surface pressures.
• This structural similarity, characterized by DPPC-enriched interfacial monolayers, is consistent across different preparations.
• Findings provide foundational insights into surfactant film behavior, potentially guiding the development of improved surfactant therapies for respiratory diseases.