Thermodynamic Insights into Native Pulmonary Surfactant Films: Elastic Compression Modulus and Energy Dissipation...

Area of Science:

• Biophysics
• Respiratory Physiology

Background:

• Native pulmonary surfactant (NPS) is crucial for lung function by reducing surface tension.
• Understanding NPS biophysical activity is essential for assessing respiratory mechanics.

Purpose of the Study:

• To systematically characterize the interfacial activity and mechanical stability of porcine NPS films.
• To establish functional performance metrics for pulmonary surfactant films based on energetics and thermodynamics.

Main Methods:

• Utilized standard surface balances for in vitro characterization of NPS films at a model air-liquid interface.
• Measured adsorption kinetics, isothermal compression, and cyclic compression-expansion.
• Calculated compressive elastic modulus and hysteresis using fitted polynomial trajectories.

Main Results:

• NPS films exhibited remarkable interfacial mechanical stability, with a constant compressive elastic modulus across cycles.
• Hysteresis between compression and expansion isotherms indicated irreversibility, with energy requirements decreasing over cycles.
• Functional performance metrics derived from compressive elastic modulus and hysteresis were established.

Conclusions:

• The study provides a functional framework for assessing pulmonary surfactant film stability and performance.
• Compressive elastic modulus and hysteresis serve as key metrics for evaluating surfactant function.
• This energetic and thermodynamic approach complements traditional viscoelastic characterization.