Photo from Day 49 of Project 365
While the first day of my trip to Atlanta centered on touristy activities with Eric, such as the World of Coca-Cola and the Georgia Aquarium, the second concentrated on the conference itself (Emerging Researcher’s National conference in STEM 2012.) Although my presentation Self‐Assembling Peptides with Embedded Fluorescent Cores wasn’t until the next day, there were plenty of other interesting poster and oral presentations to check out, graduate/medical schools to talk to and my oral presentation to practice. The conference was held in the Westin Peachtree hotel, a beautiful building (photo) in downtown Atlanta. While I really enjoyed talking to recruiters and finding out more about neuroscience and MD/PhD programs, that doesn’t make for much of an entry. So, instead, I’ll present the abstract that was accepted for presentation at the conference. The required format of the abstract required a great deal more detail in regard to the methods than I would normally include, but I didn’t make up the rules. This research was conducted over the two summers, 2010 and 2011, I spent working in the lab of Dr. Tovar at Johns Hopkins University via an undergraduate fellowship from the Institute of Nanobiotechnology.
Mary Bedard, Elon University, John D. Tovar, Johns Hopkins University, Dr. William L. Wilson, Johns Hopkins University; Brian Wall, Johns Hopkins University, Dr. Stephen R. Diegelmann, Johns Hopkins University
Self-assembling peptides which incorporate p-conjugated units within the peptide backbone have shown potential for bridging the gap between electronic and biological interfaces. Once assembled, the peptide units act as insulation, shielding the inner p-electron rich portion. This assembly process forms fibers which are 1-5 nm in diameter and in excess of 1 micron in length, very similar to β amyloid plaques. This produces overlap of the internal p-electrons in the center of the assembled fibers. Meanwhile, the peptide chain forms the outer section of the fiber and is free to interact with cells. The present study sought to engineer various peptide chains with embedded chromophores that demonstrate the self-assembly process in order to probe characteristics of the process and to examine the possibility of further assembling these fibers into macroscopic noodles, or nanowires. Elucidating the process of assembly of amyloid fibers may provide insight into the emergence of β amyloid plagues associated with diseases such as Alzheimer’s and Parkinson’s. Peptides were synthesized by solid phase synthesis and purified with High Performance Liquid Chromatography (HPLC). Rapid extrusion of approximately 10 μL of slightly basic 1 wt. % purified peptide solution into 1 M HCl successfully yielded aligned, birefringent noodles. Uniformly aligned noodles were identified with Polarized Optical Microscopy (POM) and Scanning Electron Microscopy (TEM). Feasibility of aligned noodles as nanowires was examined by incorporation of sequences associated with neuronal cells, specifically IKVAV, into the peptide unit. Human Neuron Crest Stem Cells seeded on top of a random peptide gel yielded increased neuron differentiation and network growth, indicating minimal toxicity to cells. Characteristics of the self-assembly process of amyloid fibers were studied with Fluorescence Correlation Spectroscopy (FCS), with aggregates observed in basic peptide solutions upon addition of acid or exposure to acid vapor. Overall, the data indicates successful creation of self-assembling peptides, a method of assembly to produce noodles constituted of aligned amyloid fibers and the possibility of their implementation in a biological setting. Future research focuses on continuation of FCS analysis to understand the mechanics of the self-assembly process and further cell work to determine the viability and efficiency of the nanowires.
[This study was supported, in part, by the Research Experience for Undergraduates (REU) program offered by the Institute of Nanobiotechnology at Johns Hopkins University with funding from NSF ].
More about my adventures in Atlanta, in between conference activities, can be found under Atlanta trip.