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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
82
75-POS
Board 38
Oxidation of Serum Proteins by Titanium Dioxide Nanoparticles Leads to Oxidative Stress
Sabiha Runa
1
, Dhanya Jayaram
1
, Melike Lakadamyali
2
, Melissa L. Kemp
3,4
.Christine K.
Payne
1,4
.
3
Georgia Institute of Technology, Atlanta, GA, USA,
1
Georgia Institute of Technology, Atlanta,
GA, USA,
4
Georgia Institute of Technology, Atlanta, GA, USA.
2
Institute de Ciencies Fotonics,
Castelldefels, Barcelona, Spain,
The Payne Lab at Georgia Tech has shown that titanium dioxide (TiO
2
) nanoparticles (NPs) lead
to oxidative stress in human cells in the absence of light. Changes in gene expression of the
peroxiredoxin family of antioxidant enzymes were observed after 24 hours of TiO
2
NP
incubation using reverse transcription polymerase chain reaction and western blotting. To
understand the mechanism behind these results, we investigated the protein corona, the serum
proteins that adsorb onto the NP surface. TiO
2
NPs oxidized the protein corona as measured with
a dinitrophenylhydrazine assay. This protein oxidation was found to mediate the observed
changes in peroxiredoxin gene expression. While these experiments related TiO
2
NP incubation
to oxidative stress, cell viability decreased only after NP incubation
in the absence
of serum
proteins, suggesting that the protein corona serves as a protective layer. Without serum proteins,
lipid peroxidation increased, indicating the NPs can directly oxidize the lipid membrane. This
was also observed after 24 hours of NP incubation when serum proteins were present, prompting
further characterization of the corona. We probed the spatial distribution of corona proteins along
the NP surface using super-resolution fluorescent microscopy. Image analysis suggests a non-
uniform arrangement with incomplete surface coverage, exposing much of the NP to the lipid
membrane. These results confirm that the protein corona facilitates the multiple oxidation
outcomes experienced by cells.