Icon for: Andrew Durney

ANDREW DURNEY

University of Rochester
Years in Grad School: 2

Judges’ Queries and Presenter’s Replies

  • Icon for: Qiaobing Xu

    Qiaobing Xu

    Judge
    May 20, 2013 | 09:35 p.m.

    nice work, Andrew. what gene do you have in mind to deliver into algae for your application? what’s the commonly used methods that are currently used for gene delivery into algae?

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    Andrew Durney

    Presenter
    May 21, 2013 | 09:21 a.m.

    Thank you, Dr. Xu.

    In order to prove the concept of gene delivery, we will be using a reporter gene such as orange fluorescent protein. Because this is an exogene, only the transfected cells will express it.

    There are a few different methods of gene delivery currently used, including biolistic transformation, electroporation, and agitation with glass beads or whiskers. Each has its shortcomings: cost, low-throughput, specialized equipment, or removal of the algal cell wall. Our platform should overcome all these challenges.

  • May 21, 2013 | 09:27 a.m.

    Great presentation Andrew. Are there any technical challenges that need to be overcome in making the hollow needles? Also, do we know how the algae “heal” themselves once the genes are injected into the cytoplasm? Are there proof-of principle studies on this point?

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    Andrew Durney

    Presenter
    May 21, 2013 | 10:17 a.m.

    Thanks, Dr. Baskaran.

    I think that obtaining a uniformly thick gold deposition layer will be the critical challenge in obtaining hollow needles that have a narrow distribution in their tip openings. The thickness of the gold layer defines the relationship between the tip openings’ outer and inner diameters, which will need to be precisely tuned for optimal piercing of algae cells and transport of DNA through the openings.

    Regarding the healing of the cells after piercing: this is not a concern for us because we do not intend for the pierced cells to leave the needles. Instead, the cells remain alive on the microneedle array and replicate according to normal cell function. The transfected genes are passed on to the daughter cells, which are not themselves pierced on the needles. If the transfection is successful, the new genes will remain with the entire culture from then on.

  • May 21, 2013 | 06:09 p.m.

    Great works. Did you have a chance to evaluate viability and gene expression level of algae which contacted microneedles?

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    Andrew Durney

    Presenter
    May 22, 2013 | 08:31 a.m.

    Thanks for your comment, Dr. Kong.
    So far in our lab, we have not yet delivered any genes. However, during her post-doctoral research at the University of Florida, my advisor, Hitomi Mukaibo, was able to tether DNA to solid microneedles and pierce algae. She evaluated both cell viability and gene expression; the manuscript has been submitted to a journal for review.

  • May 21, 2013 | 06:32 p.m.

    Nice work, nice needles and a great goal. My question, why not to use other kinds of nanoneedles, which are already reported in literature. What are the main advantages of your approach?

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    Andrew Durney

    Presenter
    May 22, 2013 | 08:40 a.m.

    Thank you, Dr. Noginova.
    The shape of our needles is critical; the conical shape provides both a sharp point that is able to puncture the rigid cell wall as well as a wide base that provides mechanical strength. Because the microalgae have a cell wall, a significant force is required to pierce them, which sets our microneedle platform apart from others. Lastly, the template synthesis method we use is simple and does not require the nanofabrication techniques that many other nanoneedles are made with.

  • Icon for: Qi-Huo Wei

    Qi-Huo Wei

    Judge
    May 21, 2013 | 08:57 p.m.

    Interesting idea. Have you thought about how high concentration of DNA is needed to have sufficient diffusion flow into the cells?

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    Andrew Durney

    Presenter
    May 22, 2013 | 08:48 a.m.

    Thanks for commenting, Dr. Wei.
    We have certainly thought about DNA concentration, but don’t yet have any numbers to reference. The amount of DNA required will clearly need to be optimized to provide a sufficiently high driving force for diffusion while minimizing cost.

  • Further posting is closed as the competition has ended.

Presentation Discussion
  • May 21, 2013 | 11:57 a.m.

    Interesting work. What is the composition of the plug on the needles and what components does it interact with in the cell that leads to its breakdown?

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    Andrew Durney

    Presenter
    May 21, 2013 | 12:08 p.m.

    Thanks for your comments, Myisha. The answer to your question is actually the focus of my poster presentation. The plug consists of the biopolymer chitosan and a crosslinker that contains a disulfide bond. The disulfide bond can be reduced, or cleaved, by free thiol-containing compounds within the algae cells. We highlight the tripeptide glutathione as a candidate reducing agent, and demonstrate its ability to degrade the plug in vitro.

  • May 22, 2013 | 08:00 a.m.

    Cool technique for DNA delivery. Nice FE-SEM image of the algae on the needle.

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    Andrew Durney

    Presenter
    May 22, 2013 | 08:54 a.m.

    Thanks for commenting, Philomena. I had a really good teacher in electron microscopy.

  • Further posting is closed as the competition has ended.