2024 AIChE Annual Meeting
Nano-Invaders: Unraveling the Secrets of Nanoparticle-Lung Interactions
Airborne nanoparticles, both natural and engineered, are becoming an increasing concern due to their potential impacts on human health and the environment. The increasing frequency and intensity of wildfires driven by climate change are generating higher levels of airborne carbonaceous particles. The inhalation of fine particulate matter from wildfires has been linked to adverse pulmonary health outcomes and there is a critical need to better understand the interactions between airborne nanoparticles and the human respiratory system, particularly the effects of inhaled particles on the lung surfactant system - the first line of defense against foreign materials in the alveolar space. The alveolar boundary in the lungs was modeled with 50 nm silica nanoparticles (SNPs), which were modified with trimethoxy silanes with varying carbon tail chain length groups dispersed onto dipalmitoylphosphatidylcholine (DPPC), the main component of the pulmonary surfactant. Utilizing surface and interfacial tension measurements through the optical shape analysis of a pendant drop apparatus, the interfacial behavior of the DPPC and modified SNP monolayers were examined through dilational rheology experiments and surface pressure-area isotherms. Our studies demonstrate that with increasing carbon tail lengths of the modified nanoparticles the DPPC monolayers were subject to stronger intermolecular interactions. This is due to strong van der Waals interactions between the hydrophobized nanoparticles and the acyl chains of the DPPC molecules. These interactions lead to more condensed and densely packed DPPC/SNP monolayers as carbon tail length increases. Despite the increasing radial length of the coupling agents, our studies show that the larger increase in hydrophobicity is the stronger force condensing the DPPC monolayer. This is in contrast to the unmodified SNP, which with no carbon tail functionalization, was attracted to the hydrophilic region of the monolayer, decreasing the density of the monolayer. The intermolecular interactions caused by the presence of nanoparticles in the monolayers were attributed to the surface pressure-area isotherms. Additionally, dilational rheology experiments determined the packing density and viscoelastic properties of the DPPC/SNP monolayers. As the carbon tail lengths of the modified silica nanoparticles increased, resulting in increasing surface hydrophobicity, reduced the mean molecular area of the DPPC monolayers. These findings provide important insights into the interactions between airborne nanoparticles and the LS system, which is essential for maintaining proper lung function, and improve our understanding of how the physicochemical properties of nanoparticles influence their impact on LS. These findings shed light on the potential health risks associated with exposure to airborne nanoparticles from natural sources.