348905 Vertically Aligned Multi-Walled Carbon Nanotubes As a Delivery Vehicle to Activate an Immune Response

Monday, November 4, 2013
Grand Ballroom B (Hilton)
Elizabeth Allan-Cole, CBEE, Oregon State University, Corvallis, OR, Jun Jiao, Physics and Mechanical and Materials Engineering, Portland State University, Portland, OR and Lester Lampert, Physics, Portland State University, Portland, OR

Vertically aligned multi-walled carbon nanotubes (MWCNTs) were used as a delivery vehicle for ovalbumin (OVA) in mouse dendritic cells strain 2.4. The goal of this project was to show that vertically aligned fixed MWCNTs can deliver OVA and activate an immune response detected by an MHC class I antibody tagged with a fluorescent dye.

This research was conducted in vitro using fixed and aligned MWCNTs rather than ones in solution. Many other studies have been conducted using MWCNTs as a delivery pathway where either a peptide, or nucleic acid is delivered to cells. This study emphasized fixed MWCNTs on a silicon substrate; they can be used to isolate specific cells and control delivery better than MWCNTs in solution. Also, this control could potentially help determine the mechanism at the interface of the cell and the MWCNTs. This study also depends on the low cytotoxicity of the MWCNT, which is still under debate in the nano-biological world.

Multi-walled carbon nanotubes were grown in a Plasma Enhanced Chemical Vapor Deposition System (PECVD) on a silicon substrate using a 3.5 nm thick nickel catalyst. Using a two-step hydrothermal process the MWCNTs were then decorated with gold nanoparticles. Once gold was attached to the MWCNTs 4-aminothiophenol was used as a liker for the conjugation of OVA to the nanotubes. Once OVA was conjugated with the nanotubes, it was then delivered to cells during cell culturing. A fluorescent MHC class I tag specific to SIINFEKL, a peptide from OVA, was added to the cells to confirm the delivery of OVA. The antibody also confirmed that an immune response was activated by showing the expression of MHC class I on the cells.

The successful delivery was the key to this project. If delivery was successful in mouse dendritic cells then this could be a potential new delivery pathway. Positive MHC class I expression was observed using fluorescent imaging. This indicated a successful delivery of OVA and that an immune response was activated. This expression of MHC class I indicated that the nanotubes could be going intracellular and that the OVA was being delivered directly into the cell. More tests need to be conducted to reproduce these results. The next step prescribed will be to confirm these results with the TEM (transmission electron microscope). This will be done in future work. There are many possible interferences that could have contributed to the results. Gold can affect fluorescence, which could have given a false positive had nanoparticles been close enough to the fluorescent tag. There could also be an issue with the MWCNTs as the delivery vehicle; the OVA could be in solution and still be delivered in the media. More needs to be done regarding MWCNTs as the delivery vehicle.

In conclusion, there was a positive delivery of OVA to the cells which successfully activated an immune response. This could be seen in the expression of the OVA specific MHC class I expression with a fluorescent tag. Given the positive results, this process can now be replicated and varied to confirm that the MWCNTs are the vehicle and gold nanoparticles are not interfering with the fluorescence. The next step prescribed will be to confirm these results with the TEM (transmission electron microscope). Patterned substrates will be used in the future for evidence that the MWCNTs s are the delivery vehicle. Αlpha-alumina nanowire will be compared to the MWCNTs in the future to determine the best form of delivery. Looking at the way MHC class II expression occurs will be a future consideration. In the future, once the results are confirmed, this process could be used in actual T cells and the immune response could be observed in vivo.

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