Date of Award

5-2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

Advisor

Dean, Delphine

Committee Member

Kitchens , Christopher

Committee Member

Alexis , Frank

Abstract

In this master's thesis we look at elucidating the interactions between nanoparticles and cells. Specifically, we looked at how the cell mechanics are affected, cytotoxicity of the nanoparticles, and shifts in cell phenotypes. There has been much research looking into whether nanoparticles are cytotoxic, but limited amounts looking at their effect on mechanics especially with vascular smooth muscle cells. This cell type has two distinct phenotypes of synthetic and contractile that each serve different purposes physiologically.
The first experiments we did were cytotoxicity assays to see if the cells could survive the treatment with nanoparticles. If the cells died within a short period of time then we wouldn't be able to take the next step and look at the mechanics of the cells. Most of the nanoparticles used proved to cause no change in proliferation rate of the cells; however, a couple did show some cytotoxic effects and were not used for further experimentation.
Since the cells were surviving and proliferating after treatment with these nanoparticles we did atomic force microscopy to determine the elastic modulus of the cells that were treated with nanoparticles and those that were untreated. This allowed us to see if there was a significant increase or decrease caused by the nanoparticles. The results showed that there was a significant decrease in the elastic modulus of the cells treated with nanoparticles.
Finally, we wanted to observe any possible phenotypic shifts in the cells by using immunofluorescence. The cells were stained for actin, microtubules (the main components of the cell's cytoskeleton and thus mechanics), and nuclei. Vascular smooth muscle cells at low passage number in culture are typically in the contractile phase and this was proven with our images. The nanoparticle treated cells showed a shift towards the synthetic phenotype which confirmed the decrease in elastic modulus from the AFM data. So, while these nanoparticles are not cytotoxic we are causing a significant change in the cells' mechanics and phenotype.

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