New Insights into Cation- and Temperature-Driven Protein Adsorption to the Air–Water Interface through Infrared Reflection Studies of Bovine Serum Albumin

Abstract

The chemistry and structure of the air–ocean interface modulate biogeochemical processes between the ocean and atmosphere and therefore impact sea spray aerosol properties, cloud and ice nucleation, and climate. Protein macromolecules are enriched in the sea surface microlayer and have complex adsorption properties due to the unique molecular balance of hydrophobicity and hydrophilicity. Additionally, interfacial adsorption properties of proteins are of interest as important inputs for ocean climate modeling. Bovine serum albumin is used here as a model protein to investigate the dynamic surface behavior of proteins under several variable conditions including solution ionic strength, temperature, and the presence of a stearic acid (C17COOH) monolayer at the air–water interface. Key vibrational modes of bovine serum albumin are examined via infrared reflectance–absorbance spectroscopy, a specular reflection method that ratios out the solution phase and highlights the aqueous surface to determine, at a molecular level, the surface structural changes and factors affecting adsorption to the solution surface. Amide band reflection absorption intensities reveal the extent of protein adsorption under each set of conditions. Studies reveal the nuanced behavior of protein adsorption impacted by ocean-relevant sodium concentrations. Moreover, protein adsorption is most strongly affected by the synergistic effects of divalent cations and increased temperature.

Interfacial carbonyl groups of propylene carbonate facilitate the reversible binding of nitrogen dioxide

“…Infrared reflection-absorption spectroscopy IRRAS has been previously employed by this lab to elucidate molecular changes at a variety of interfaces [44][45][46][47][48][49][50] and is employed here with modifications to allow for studies involving NO 2 gas at organic interfaces. Spectra were collected using a PerkinElmer Spectrum 3 FTIR spectrometer equipped with a custom-built mirror array within the sample compartment.…”

Interfacial Carbonyl Groups of Propylene Carbonate and Diethyl Sebacate Facilitate the Reversible Binding of Nitrogen Dioxide

“…Infrared Reflection-Absorption Spectroscopy IRRAS has been previously employed by this lab to elucidate molecular changes at a variety of interfaces [44][45][46][47][48][49][50] and is employed here with modifications to allow for studies involving NO2 gas at organic interfaces. Spectra were collected using a PerkinElmer Spectrum 3 FTIR spectrometer equipped with a custom-built mirror array within the sample compartment.…”