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Investigation of the Biophysical Effect of Hydrophobic Nanoparticle Exposure on Pulmonary Surfactant Films

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Item Summary

Title:Investigation of the Biophysical Effect of Hydrophobic Nanoparticle Exposure on Pulmonary Surfactant Films
Authors:Valle, Russell
Date Issued:May 2015
Publisher:[Honolulu] : [University of Hawaii at Manoa], [May 2015]
Abstract:The demand for nanoparticles (NPs) has reached a point where large quantities are being manufactured everyday in nations around the globe. Due to the mass production of NPs, many concerns have arisen about the adverse effects of NPs on human health. An area of focus is the pulmonary system, because many NPs are lightweight and respirable. The first biological barrier with which inhaled NPs come in contact is the pulmonary surfactant (PS) matrix. PS is a lipoprotein complex that lines the entirety of the peripheral lung. The chief functions of the PS matrix are, first, to act in innate immunity for foreign airborne contaminants that may reach the alveoli and second, to reduce alveolar surface tension values which keep the air sacs inflated and maintain normal lung function. Preliminary tests have shown that the biophysical function of PS is inhibited when exposed to NPs. The inhibition potential is dependent on the physicochemical properties of the NPs, such as size, shape, charge, and the agglomeration state. Here we investigate the surface hydrophobicity which is a rarely studied physicochemical property of NPs, but our results demonstrate that it has a significant effect on biophysical inhibition of PS. Being the most commonly used hydrophobic nanomaterials, carbon nanotubes (CNT), and more recently graphene nanoplatelets (GNP), have been extensively manufactured which raises concerns about their impact on occupational inhalation exposure. It is important to simulate the inhalation effect on PS in vitro to understand the biophysical mechanism behind the inhalation toxicity of carbon nanomaterials. Here we developed a novel experimental methodology, called the constrained drop surfactometer (CDS), to perform the first in vitro simulation of nano-bio interactions between airborne carbon nanoaerosols and PS films under physiologically relevant conditions. We found that the doses of both CNT and GNP were within international occupational exposure limits. A large majority of the aerosol aggregates for both CNT and GNP were sub-micron in size. After exposure to CNT and GNP aerosols we found a dose-dependent surfactant biophysical inhibition. Our in situ Langmuir-Blodgett transfer revealed that CNT and GNP aggregates “stick” to the surfactant film where nano-bio interactions induce surfactant inhibition. Our results are promising, demonstrating that both CNT and GNP induce a dose-dependent biophysical inhibition in concentrations comparable to many international occupational exposure limits. All of the results demonstrate that hydrophobicity is a defining pro-inhibitory characteristic of NPs that must be taken into account when studying both nanotoxicology and nanomedicine.
Description:M.S. University of Hawaii at Manoa 2015.
Includes bibliographical references.
Appears in Collections: M.S. - Mechanical Engineering

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