Medical Engineering Special Speaker

Although electron microscopy provides a platform to image and reconstruct neuronal morphology, it is slow, expensive, does not easily facilitate multicolor labeling, and is not readily accessible to most neuroscientists. Recently, our lab has introduced a new modality of imaging, Expansion Microscopy (ExM), which uses physical sample magnification and allows imaging of large 3D specimens with nanoscale resolution because fast diffraction limited optical microscopes can be used. The physical magnification of the sample results from synthesizing a series of polyelectrolyte gels network directly within the specimen, which is then physically expanded to achieve a ~15nm resolution using a common confocal microscope. Applying ExM to imaging the neuronal membrane morphology requires the development of lipid binding tags which can be anchored to the ExM hydrogel. We have designed and implemented ExM compatible lipid binding labels that can selectively bind the plasma membranes of neurons and other cells. These labels are water soluble, and have small molecular weights (<1kDa), which facilitates their fast 3D diffusion within tissue, and thus allowing staining of large tissue volumes. The tags contain chemical groups that facilitate the chemoselective conjugation of multiple types of fluorescent labels, important for multicolor and amplified labeling. We further combine the neuronal morphology with proteomic information acquired with antibody staining to achieve an integrated structural and functional mapping of neuronal interactions in the nanoscale. Biography: Emmanouil Karagiannis is a Research Scientist in the Synthetic Neurobiology laboratory of Prof. Ed Boyden at the MIT Media Lab and the MIT McGovern Institute. He develops tools for analyzing and repairing complex biological systems such as the brain. Emmanouil graduated summa cum laude from the Department of Chemical Engineering at the Aristotle University of Thessaloniki, Greece. He then moved for grad school to Baltimore, MD and did his Ph.D at the Department of Biomedical Engineering at Johns Hopkins University, School of Medicine. At Hopkins he worked in the Systems Biology Laboratory of Prof. Aleksander Popel. In the laboratory of Prof. Popel he developed computational models of the extracellular matrix proteolysis and cell migration during angiogenesis, as well as bioinformatics algorithms which contributed to the identification of a new generation of anti-angiogenic peptides. These peptides are currently developed as cancer therapeutics in a start-up company in the Baltimore area. After completing his Ph.D he moved, as a post-doctoral research fellow, to the laboratory of Prof. Bob Langer at MIT where he applied rational bioengineering methods to study drug delivery and tissue engineering problems. In the Langer lab he designed and synthesized libraries of novel cell penetrating peptides; such peptides are "magic bullets" that can deliver a variety of drugs in different tissues. He is the author of 23 peer reviewed papers, 2 book chapters and holds 2 approved and 3 pending patents. Synthetic Neurobiology Group Website: http://syntheticneurobiology.org/