Impact of Engineered Carbon Nanodiamonds on the Collapse Mechanism of Model Lung Surfactant Monolayers at the Air-Water Interface

Abstract

Understanding interactions between inhaled nanoparticles and lung surfactants (LS) present at the air-water interface in the lung, is critical to assessing the toxicity of these nanoparticles. Specifically, in this work, we assess the impact of engineered carbon nanoparticles (ECN) on the ability of healthy LS to undergo reversible collapse, which is essential for proper functioning of LS. Using a Langmuir trough, multiple compression-expansion cycles are performed to assess changes in the surface pressure vs. area isotherms with time and continuous cyclic compression-expansion. Further, theoretical analysis of the isotherms is used to calculate the ability of these lipid systems to retain material during monolayer collapse, due to interactions with ECNs. These results are complemented with fluorescence images of alterations in collapse mechanisms in these monolayer films. Four different model phospholipid systems, that mimic the major compositions of LS, are used in this study. Together, our results show that the ECN does not impact the mechanism of collapse. However, the ability to retain material at the interface during monolayer collapse, as well as re-incorporation of material after a compression-expansion cycle is altered to varying extent by ECNs and depends on the composition of the lipid mixtures.

Unraveling Complex Hysteresis Phenomenon in 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine Monolayer: Insight into Factors Influencing Surface Dynamics

“…Several studies have reported on the altered surface properties and phase behavior of lipids using the Langmuir-Blodgett technique due to variations in temperature [15][16][17], different chain lengths of acyl lipids [18][19][20], compositions with other lipids [21][22][23], mixtures with other components [24][25][26] or particles [27][28][29], differences in subphases [30][31][32][33], oxidation and degradation [34][35][36], and pH changes [37][38][39]. Only a few research cases have thoroughly investigated hysteresis using the same technique, particularly for phospholipids, e.g., [6,29,[40][41][42][43][44]. Many articles discussing hysteresis studies are predominantly found in the context of mimicking meibomian lipid films [7,[45][46][47].…”