Investigation of the Dynamic Surface Adsorption Process of Mucin Protein in the Air-Water Interface

Mucin proteins are essential components of the human respiratory system, playing a crucial role in maintaining controlled permeability through the formation of a reticulated structure and electrical charge (exhibiting high surface activity). In addition to their defensive function against external elements, mucins contribute to the dynamic equilibrium in the upper respiratory tract. This study investigates the role of electrical charge in the performance of mucin proteins by introducing and utilizing the drop profile tensiometry method to measure dynamic surface tension and surface elasticity across a wide range of mucin protein concentrations (ranging from 1 to 1000 nanomolar) in buffered solutions. The measurement results of dynamic surface tension indicate a high absorption rate of these large-molecule proteins at the air-water interface for concentrations exceeding one hundred nanomolar. This observation highlights the rapid formation of a structured protective layer in the respiratory system. The measurement of surface elasticity parameters, utilizing interfacial oscillations at different frequencies, demonstrates elevated values of elasticity within the absorbed structured layer.