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Joey Pryor is an undergraduate student in his senior year working in Dr. Stacey Harper’s laboratory. He is majoring in Biology (Pre-med) and double-minoring in Toxicology and Chemistry. He began doing research with Stacey in 2012 as part of the thesis requirements for OSU Honors Baccalaureate College. Joey has received multiple scholarships and awards to fund his research, and recently published his research in the International Journal of Nanomedicine. His article is freely available here.
Joey has been awarded 9 research scholarships, totaling over $33,000 to support his research and associated research costs.
What is your research focus? I am researching the toxicity of dendrimers, which are a class of nanoparticles. Dendrimers are spherical, branching nanoparticles that look a lot like tumbleweeds because of their hollow core and clustered surface. Due to the hollow core, dendrimers are able to carry cargo, making them ideal for both gene therapy and drug delivery. Before dendrimers can be used in such a way though, we need to better understand the potential for toxicity. Research has shown that some dendrimers are toxic, while others are not. Additionally, from other studies in our lab and in the literature, we know that there are three factors that appear to influence toxicity: size of nanomaterial, the composition (type of material) and the charge (positive, negative, or neutral).
What is your paper about? In order to identify the driving factor behind toxicity, we designed an experiment to investigate the role dendrimer size, composition, and charge plays in toxicity. To evaluate toxicity, we used the embryonic zebrafish as a model organism (see Figure below) and the Embryonic Zebrafish (EZ) metric assay, which was designed by Dr. Harper [1-3]. The EZ metric evaluates sub-lethal endpoints of toxicity (cardiac edema, body malformations, and behavioral deficits) as well as overall mortality. We tested 12 different types of dendrimers that varied in size, composition and charge.
|Embryonic zebrafish development from day 1 (24 hours) to 5 days (120 hours)||A Polyamindoamine (PAMAM) Dendrimer|
|24 hours post-fertilization||120 hours post fertilization||Example of a dendrimer that zebrafish were exposed to|
What did you find? We found that charge was the most influential factor when assessing toxicity. Dendrimers with a positive charge resulted in 100% mortality by day five at the highest concentration. In contrast, zebrafish exposed to other negative and neutral dendrimers exhibited minimal mortality and sub-lethal effects, even at our highest dose of 250 parts per million.
What is the significance of these findings? As I mentioned earlier, dendrimers are being explored for their use as a drug delivery mechanism. You can load the drug inside the dendrimer, and the dendrimer can be created in such a way to carry the drug directly to a targeted site in the body. Currently, researchers have been looking at PAMAM dendrimers. PAMAM is short for polyamidoamine, meaning these dendrimers are covered in amine groups (see figure above). PAMAMs have a positive charge, and our research shows that these dendrimers are more toxic than their negative or neutral counterparts.
We often say in science that we start with one question, and end up with infinitely more. That's probably why so many of us enjoy science - there are always questions to ask! You started with one question; did your research provide you with new questions? It did. We showed that positively-charged dendrimers resulted in toxicity to the embryonic zebrafish. But all of those dendrimers also contained amine groups. So the million dollar question would be: Is the toxicity attributed to the positive charge, or to the amine group? It’s a very specific distinction, but I think it is an important question because in the literature, cationic and amine are used interchangeably.
As an undergraduate new to the field of research science, what was the best advice you received? When I was working on this paper, it was frustrating to send out a draft to coauthors, and then get revisions back. I would look at the paper, and it would be covered in red ink. It’s easy to get discouraged, and you’re just thinking, “This will never get published!” But the other people in the lab, especially the graduate students who had published, would always say, “It’s worth it in the end.”
And was it worth it in the end? It was!
Overall, what was the most rewarding aspect of this experience? Knowing that I contributed something to science. Publishing was such a testament to the work that I have done.
Now that you have gone through this experience, do you have any advice to students interested in pursuing undergraduate research? The best advice I can give is to take the chance and talk to professors. I was worried about finding a position in a lab, but with time and a couple emails, it worked out. There are several professors that are more than willing to work with you, especially if you are dedicated and willing to learn. By getting involved in a lab, I have grown academically. Research pushed me to critically think and apply what I learned in classes to a real-life problem. For me, doing research sort of crystallized everything in my mind. As a student you take a wide variety of classes, and research helped connect the dots and show how science can work as a cohesive whole.
What is next for you? This summer I am applying for medical school. For the interim, I’m hoping to find a position in research, while also getting my certification as an emergency medical technician.
 Harper S.L., Lee S., Tanguay R.L. 2008. An EZ metric for evaluation nanomaterial biological interactions. Society of Toxicology 47th Annual Meeting
 Tang K., Liu X., Harper S.L., Steevens J.A., Xu R. 2013. NEIMiner: nanomaterial environmental impact data miner. Int. J. Nanomedicine. 8 Suppl 1:15-29
 Liu X., Tang K., Harper S., Harper B., Steevens J.A., Xu R. 2013. Predictive modeling of nanomaterial exposure effects in biological systems. Int J. Nanomedicine. 8 Suppl 1: 31-43