Electrically-Conductive Micropatterns that Promote Cell Adhesion and Neurite Extension
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1009-U02-04
Electrically-conductive micropatterns that promote cell adhesion and neurite extension Sung-Yeol Kim1, Hyun-Kon Song3, Diane Hoffman-Kim1,2, and G. Tayhas R. Palmore1,2 Division of Engineering1 Division of Biology and Medicine2 LG Chem LTD3 Brown University, Providence, RI 02912
We recently demonstrated a new strategy to modify polypyrrole (pPy) with biological molecules that relies on a polyanionic dopant containing reactive functional groups. Specifically, chemical guidance cues such as poly-L-lysine (pLys) were tethered to pPy via amide bond formation with carboxylic acid groups of the polyanionic dopant, polyglutamic acid (pGlu) using EDC/NHS coupling reactions (see figure). This strategy overcomes several shortcomings found in other approaches used to modify conducting polymers by providing a doping procedure that insures efficient utilization of the biomolecule-of-interest without having to (i) synthesize new monomers with reactive functional groups or (ii) functionalize the conductive polymer post-electrodeposition. Consequently, an important feature of this new strategy is that it can be extended to other conducting polymers (i.e., poly(3,4ethylenedioxythiophene) that are polycationic. In this presentation, we show how our strategy has been advanced beyond controlling the location of neuron adhesion and neurite outgrowth to modulating quantitatively the density of cells and their neural processes within micropatterned substrates. We attach multilayers of chemical guidance cues (e.g. pLys) to pPy via sequential EDC/NHS coupling reactions for the latter purpose. Details on the preparation of different substrates will be presented including their spectroscopic, microscopic, immunochemical and protein adsorption characterization. The density of hippocampal neurons and neurites are shown to be proportional to the surface concentration of the chemical cue (pLys). The number of cells adhered to areas outside of the micropattern will be shown to decrease as the density of the guidance cues within the micropattern increases until a physical limit of cell density is achieved
Figure. a) Schematic of a neuron adhered to a substrate consisting of polypyrrole (pPy) doped with polyglutamic acid [pGlu] and modified with poly-L-lysine (pPy[pGlu]-pLys) via amide bond formation to the protruding carboxylic acid groups of the pGlu dopant. b) Hippocampus neurons adhered preferentially to patterns of pPy[pGlu]-pLys (Dark strip) after 5 days of culture.
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