Influence of Different Acids on the Transport of CdSe Quantum Dots from Polymer Nanocomposites to Food Simulants

Patrick J. Gray; Jessica E. Hornick; Ashutosh Sharma; Rebecca G. Weiner; John L. Koontz; Timothy V. Duncan

doi:10.1021/acs.est.8b02585

Influence of Different Acids on the Transport of CdSe Quantum Dots from Polymer Nanocomposites to Food Simulants

Patrick J. Gray, Jessica E. Hornick, Ashutosh Sharma, Rebecca G. Weiner, John L. Koontz, Timothy V. Duncan^*

^*Corresponding author for this work

Molecular Biosciences

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

We fabricated polymer nanocomposites (PNCs) from low-density polyethylene and CdSe quantum dots (QDs) and used these materials to explore potential exposure after long-term storage in different acidic media that could be encountered in food contact applications. While the low-level release of QD-associated mass into all the food simulants was observed, exposure to dilute acetic acid resulted in more than double the mass transfer compared to that which occurred during exposure to dilute hydrochloric acid at the same pH. Conversely, exposure to citric acid resulted in a suppression of QD release. Permeation experiments and confocal microscopy were used to reveal mechanistic details underlying these mass-transfer phenomena. From this work, we conclude that the permeation of undissociated acid molecules into the polymer, limited by partitioning of the acids into the hydrophobic polymer, plays a larger role than pH in determining exposure to nanoparticles embedded in plastics. Although caution must be exercised when extrapolating these results to PNCs incorporating other nanofillers, these findings are significant because they undermine current thinking about the influence of pH on nanofiller release phenomena. From a regulatory standpoint, these results also support current guidance that 3% acetic acid is an acceptable acidic food simulant for PNCs fabricated from hydrophobic polymers because the other acids investigated resulted in significantly less exposure.

Original language	English (US)
Pages (from-to)	9468-9477
Number of pages	10
Journal	Environmental Science and Technology
Volume	52
Issue number	16
DOIs	https://doi.org/10.1021/acs.est.8b02585
State	Published - Aug 21 2018

Funding

The authors are grateful to Glenn J. Bastiaans, Ph.D., President of NanoOptical Materials, for his helpful insight related to QD PL and surface chemistry. The authors also thank FDA/ CFSAN for financial support of this work. The Biological Imaging Facility at Northwestern University is generously supported by the Chemistry of Life Processes Institute and the Office for Research. RGW thanks the Oak Ridge Institute for Science and Education (ORISE) program for financial support. This article has been reviewed in accordance with the U.S. Food and Drug Administration’s peer and administrative review policies and approved for publication. The statements made in this report do not represent the official position of any of the employers or affiliated organizations of the experts. Certain commercial equipment, instruments, or materials are identified in this article to foster understanding. Such identification does not imply recommendation or endorsement by the U.S. Food and Drug Administration, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

ASJC Scopus subject areas

General Chemistry
Environmental Chemistry

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10.1021/acs.est.8b02585

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title = "Influence of Different Acids on the Transport of CdSe Quantum Dots from Polymer Nanocomposites to Food Simulants",

abstract = "We fabricated polymer nanocomposites (PNCs) from low-density polyethylene and CdSe quantum dots (QDs) and used these materials to explore potential exposure after long-term storage in different acidic media that could be encountered in food contact applications. While the low-level release of QD-associated mass into all the food simulants was observed, exposure to dilute acetic acid resulted in more than double the mass transfer compared to that which occurred during exposure to dilute hydrochloric acid at the same pH. Conversely, exposure to citric acid resulted in a suppression of QD release. Permeation experiments and confocal microscopy were used to reveal mechanistic details underlying these mass-transfer phenomena. From this work, we conclude that the permeation of undissociated acid molecules into the polymer, limited by partitioning of the acids into the hydrophobic polymer, plays a larger role than pH in determining exposure to nanoparticles embedded in plastics. Although caution must be exercised when extrapolating these results to PNCs incorporating other nanofillers, these findings are significant because they undermine current thinking about the influence of pH on nanofiller release phenomena. From a regulatory standpoint, these results also support current guidance that 3% acetic acid is an acceptable acidic food simulant for PNCs fabricated from hydrophobic polymers because the other acids investigated resulted in significantly less exposure.",

author = "Gray, {Patrick J.} and Hornick, {Jessica E.} and Ashutosh Sharma and Weiner, {Rebecca G.} and Koontz, {John L.} and Duncan, {Timothy V.}",

note = "Funding Information: The authors are grateful to Glenn J. Bastiaans, Ph.D., President of NanoOptical Materials, for his helpful insight related to QD PL and surface chemistry. The authors also thank FDA/ CFSAN for financial support of this work. The Biological Imaging Facility at Northwestern University is generously supported by the Chemistry of Life Processes Institute and the Office for Research. RGW thanks the Oak Ridge Institute for Science and Education (ORISE) program for financial support. This article has been reviewed in accordance with the U.S. Food and Drug Administration{\textquoteright}s peer and administrative review policies and approved for publication. The statements made in this report do not represent the official position of any of the employers or affiliated organizations of the experts. Certain commercial equipment, instruments, or materials are identified in this article to foster understanding. Such identification does not imply recommendation or endorsement by the U.S. Food and Drug Administration, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. Publisher Copyright: {\textcopyright} Copyright 2018 American Chemical Society.",

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AU - Koontz, John L.

AU - Duncan, Timothy V.

N1 - Funding Information: The authors are grateful to Glenn J. Bastiaans, Ph.D., President of NanoOptical Materials, for his helpful insight related to QD PL and surface chemistry. The authors also thank FDA/ CFSAN for financial support of this work. The Biological Imaging Facility at Northwestern University is generously supported by the Chemistry of Life Processes Institute and the Office for Research. RGW thanks the Oak Ridge Institute for Science and Education (ORISE) program for financial support. This article has been reviewed in accordance with the U.S. Food and Drug Administration’s peer and administrative review policies and approved for publication. The statements made in this report do not represent the official position of any of the employers or affiliated organizations of the experts. Certain commercial equipment, instruments, or materials are identified in this article to foster understanding. Such identification does not imply recommendation or endorsement by the U.S. Food and Drug Administration, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. Publisher Copyright: © Copyright 2018 American Chemical Society.

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N2 - We fabricated polymer nanocomposites (PNCs) from low-density polyethylene and CdSe quantum dots (QDs) and used these materials to explore potential exposure after long-term storage in different acidic media that could be encountered in food contact applications. While the low-level release of QD-associated mass into all the food simulants was observed, exposure to dilute acetic acid resulted in more than double the mass transfer compared to that which occurred during exposure to dilute hydrochloric acid at the same pH. Conversely, exposure to citric acid resulted in a suppression of QD release. Permeation experiments and confocal microscopy were used to reveal mechanistic details underlying these mass-transfer phenomena. From this work, we conclude that the permeation of undissociated acid molecules into the polymer, limited by partitioning of the acids into the hydrophobic polymer, plays a larger role than pH in determining exposure to nanoparticles embedded in plastics. Although caution must be exercised when extrapolating these results to PNCs incorporating other nanofillers, these findings are significant because they undermine current thinking about the influence of pH on nanofiller release phenomena. From a regulatory standpoint, these results also support current guidance that 3% acetic acid is an acceptable acidic food simulant for PNCs fabricated from hydrophobic polymers because the other acids investigated resulted in significantly less exposure.

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Influence of Different Acids on the Transport of CdSe Quantum Dots from Polymer Nanocomposites to Food Simulants

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