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Adaptive methodology to determine hydrophobicity of nanomaterials in situ

The hydrophobicity of nanoparticles (NPs) is a key property determining environmental fate, biological partitioning and toxicity. However, methods to characterize surface hydrophobicity are not uniformly applied to NPs and cannot quantify surface changes in complex environments. Existing methods des...

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Autores principales: Crandon, Lauren E., Boenisch, Kylie M., Harper, Bryan J., Harper, Stacey L.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7269256/
https://www.ncbi.nlm.nih.gov/pubmed/32492068
http://dx.doi.org/10.1371/journal.pone.0233844
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author Crandon, Lauren E.
Boenisch, Kylie M.
Harper, Bryan J.
Harper, Stacey L.
author_facet Crandon, Lauren E.
Boenisch, Kylie M.
Harper, Bryan J.
Harper, Stacey L.
author_sort Crandon, Lauren E.
collection PubMed
description The hydrophobicity of nanoparticles (NPs) is a key property determining environmental fate, biological partitioning and toxicity. However, methods to characterize surface hydrophobicity are not uniformly applied to NPs and cannot quantify surface changes in complex environments. Existing methods designed to evaluate the hydrophobicity of bulk solids, chemicals, and proteins have significant limitations when applied to NPs. In this study, we modified and evaluated two methods to determine the hydrophobicity of NPs, hydrophobic interaction chromatography (HIC) and dye adsorption, and compared them to the standard octanol-water partitioning protocol for chemicals. Gold, copper oxide, silica, and amine-functionalized silica NPs were used to evaluate methods based on their applicability to NPs that agglomerate and have surface coatings. The octanol water partitioning and HIC methods both measured Au NPs as hydrophilic, but despite having a small size and stable suspension, NPs could not be fully recovered from the HIC column. For the dye adsorption method, hydrophobic (Rose Bengal) and hydrophilic (Nile Blue) dyes were adsorbed to the NP surface, and linear isotherm parameters were used as a metric for hydrophobicity. CuO was determined to be slightly hydrophilic, while SiO(2) was hydrophilic and Ami-SiO(2) was hydrophobic. The advantages and limitations of each method are discussed, and the dye adsorption method is recommended as the most suitable for application across broad classes of nanomaterials. The dye assay method was further used to measure changes in the surface hydrophobicity of TiO(2) NPs after being suspended in natural water collected from the Alsea Rivers watershed in Oregon. TiO(2) NPs adsorbed Rose Bengal when suspended in ultrapure water, but adsorbed Nile Blue after being incubated in natural water samples, demonstrating a shift from hydrophobic to hydrophilic properties on the outer surface. The dye adsorption method can be applied to characterize surface hydrophobicity of NPs and quantify environmental transformations, potentially improving environmental fate models.
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spelling pubmed-72692562020-06-10 Adaptive methodology to determine hydrophobicity of nanomaterials in situ Crandon, Lauren E. Boenisch, Kylie M. Harper, Bryan J. Harper, Stacey L. PLoS One Research Article The hydrophobicity of nanoparticles (NPs) is a key property determining environmental fate, biological partitioning and toxicity. However, methods to characterize surface hydrophobicity are not uniformly applied to NPs and cannot quantify surface changes in complex environments. Existing methods designed to evaluate the hydrophobicity of bulk solids, chemicals, and proteins have significant limitations when applied to NPs. In this study, we modified and evaluated two methods to determine the hydrophobicity of NPs, hydrophobic interaction chromatography (HIC) and dye adsorption, and compared them to the standard octanol-water partitioning protocol for chemicals. Gold, copper oxide, silica, and amine-functionalized silica NPs were used to evaluate methods based on their applicability to NPs that agglomerate and have surface coatings. The octanol water partitioning and HIC methods both measured Au NPs as hydrophilic, but despite having a small size and stable suspension, NPs could not be fully recovered from the HIC column. For the dye adsorption method, hydrophobic (Rose Bengal) and hydrophilic (Nile Blue) dyes were adsorbed to the NP surface, and linear isotherm parameters were used as a metric for hydrophobicity. CuO was determined to be slightly hydrophilic, while SiO(2) was hydrophilic and Ami-SiO(2) was hydrophobic. The advantages and limitations of each method are discussed, and the dye adsorption method is recommended as the most suitable for application across broad classes of nanomaterials. The dye assay method was further used to measure changes in the surface hydrophobicity of TiO(2) NPs after being suspended in natural water collected from the Alsea Rivers watershed in Oregon. TiO(2) NPs adsorbed Rose Bengal when suspended in ultrapure water, but adsorbed Nile Blue after being incubated in natural water samples, demonstrating a shift from hydrophobic to hydrophilic properties on the outer surface. The dye adsorption method can be applied to characterize surface hydrophobicity of NPs and quantify environmental transformations, potentially improving environmental fate models. Public Library of Science 2020-06-03 /pmc/articles/PMC7269256/ /pubmed/32492068 http://dx.doi.org/10.1371/journal.pone.0233844 Text en © 2020 Crandon et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Crandon, Lauren E.
Boenisch, Kylie M.
Harper, Bryan J.
Harper, Stacey L.
Adaptive methodology to determine hydrophobicity of nanomaterials in situ
title Adaptive methodology to determine hydrophobicity of nanomaterials in situ
title_full Adaptive methodology to determine hydrophobicity of nanomaterials in situ
title_fullStr Adaptive methodology to determine hydrophobicity of nanomaterials in situ
title_full_unstemmed Adaptive methodology to determine hydrophobicity of nanomaterials in situ
title_short Adaptive methodology to determine hydrophobicity of nanomaterials in situ
title_sort adaptive methodology to determine hydrophobicity of nanomaterials in situ
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7269256/
https://www.ncbi.nlm.nih.gov/pubmed/32492068
http://dx.doi.org/10.1371/journal.pone.0233844
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