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Oxidation of Polyunsaturated Lipid Membranes by Photocatalytic Titanium Dioxide Nanoparticles : Role of pH and Salinity

Parra-Ortiz, Elisa ; Malekkhaiat Häffner, Sara ; Saerbeck, Thomas ; Skoda, Maximilian W.A. ; Browning, Kathryn L. and Malmsten, Martin LU (2020) In ACS Applied Materials and Interfaces 12(29). p.32446-32460
Abstract

In the present study, UV-induced membrane destabilization by TiO2 (anatase) nanoparticles was investigated by neutron reflectometry (NR), small-angle X-ray scattering (SAXS), quartz crystal microbalance with dissipation (QCM-D), dynamic light scattering (DLS), and ζ-potential measurements for phospholipid bilayers formed by zwitterionic palmitoyloleoylphosphatidylcholine (POPC) containing biologically relevant polyunsaturations. TiO2 nanoparticles displayed pH-dependent binding to such bilayers. Nanoparticle binding alone, however, has virtually no destabilizing effects on the lipid bilayers. In contrast, UV illumination in the presence of TiO2 nanoparticles activates membrane destabilization as a result of lipid oxidation caused by the... (More)

In the present study, UV-induced membrane destabilization by TiO2 (anatase) nanoparticles was investigated by neutron reflectometry (NR), small-angle X-ray scattering (SAXS), quartz crystal microbalance with dissipation (QCM-D), dynamic light scattering (DLS), and ζ-potential measurements for phospholipid bilayers formed by zwitterionic palmitoyloleoylphosphatidylcholine (POPC) containing biologically relevant polyunsaturations. TiO2 nanoparticles displayed pH-dependent binding to such bilayers. Nanoparticle binding alone, however, has virtually no destabilizing effects on the lipid bilayers. In contrast, UV illumination in the presence of TiO2 nanoparticles activates membrane destabilization as a result of lipid oxidation caused by the generation of reactive oxygen species (ROS), primarily •OH radicals. Despite the short diffusion length characterizing these, the direct bilayer attachment of TiO2 nanoparticles was demonstrated to not be a sufficient criterion for an efficient UV-induced oxidation of bilayer lipids, the latter also depending on ROS generation in bulk solution. From SAXS and NR, minor structural changes were seen when TiO2 was added in the absence of UV exposure, or on UV exposure in the absence of TiO2 nanoparticles. In contrast, UV exposure in the presence of TiO2 nanoparticles caused large-scale structural transformations, especially at high ionic strength, including gradual bilayer thinning, lateral phase separation, increases in hydration, lipid removal, and potential solubilization into aggregates. Taken together, the results demonstrate that nanoparticle-membrane interactions ROS generation at different solution conditions act in concert to induce lipid membrane destabilization on UV exposure and that both of these need to be considered for understanding the performance of UV-triggered TiO2 nanoparticles in nanomedicine.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
lipid membranes, lipid oxidation, nanoparticles, photocatalysis, polyunsaturation
in
ACS Applied Materials and Interfaces
volume
12
issue
29
pages
15 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:32589394
  • scopus:85088492605
ISSN
1944-8244
DOI
10.1021/acsami.0c08642
language
English
LU publication?
yes
id
1baa80cc-dab4-4fe7-a306-518586c7ac6f
date added to LUP
2020-08-04 10:59:20
date last changed
2020-09-30 10:30:50
@article{1baa80cc-dab4-4fe7-a306-518586c7ac6f,
  abstract     = {<p>In the present study, UV-induced membrane destabilization by TiO2 (anatase) nanoparticles was investigated by neutron reflectometry (NR), small-angle X-ray scattering (SAXS), quartz crystal microbalance with dissipation (QCM-D), dynamic light scattering (DLS), and ζ-potential measurements for phospholipid bilayers formed by zwitterionic palmitoyloleoylphosphatidylcholine (POPC) containing biologically relevant polyunsaturations. TiO2 nanoparticles displayed pH-dependent binding to such bilayers. Nanoparticle binding alone, however, has virtually no destabilizing effects on the lipid bilayers. In contrast, UV illumination in the presence of TiO2 nanoparticles activates membrane destabilization as a result of lipid oxidation caused by the generation of reactive oxygen species (ROS), primarily •OH radicals. Despite the short diffusion length characterizing these, the direct bilayer attachment of TiO2 nanoparticles was demonstrated to not be a sufficient criterion for an efficient UV-induced oxidation of bilayer lipids, the latter also depending on ROS generation in bulk solution. From SAXS and NR, minor structural changes were seen when TiO2 was added in the absence of UV exposure, or on UV exposure in the absence of TiO2 nanoparticles. In contrast, UV exposure in the presence of TiO2 nanoparticles caused large-scale structural transformations, especially at high ionic strength, including gradual bilayer thinning, lateral phase separation, increases in hydration, lipid removal, and potential solubilization into aggregates. Taken together, the results demonstrate that nanoparticle-membrane interactions ROS generation at different solution conditions act in concert to induce lipid membrane destabilization on UV exposure and that both of these need to be considered for understanding the performance of UV-triggered TiO2 nanoparticles in nanomedicine.</p>},
  author       = {Parra-Ortiz, Elisa and Malekkhaiat Häffner, Sara and Saerbeck, Thomas and Skoda, Maximilian W.A. and Browning, Kathryn L. and Malmsten, Martin},
  issn         = {1944-8244},
  language     = {eng},
  number       = {29},
  pages        = {32446--32460},
  publisher    = {The American Chemical Society (ACS)},
  series       = {ACS Applied Materials and Interfaces},
  title        = {Oxidation of Polyunsaturated Lipid Membranes by Photocatalytic Titanium Dioxide Nanoparticles : Role of pH and Salinity},
  url          = {http://dx.doi.org/10.1021/acsami.0c08642},
  doi          = {10.1021/acsami.0c08642},
  volume       = {12},
  year         = {2020},
}