Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

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.

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