Abstract

Chemical gradients drive many processes in biology, ranging from nerve signal transduction to ovulation. At present, microscopy is the primary tool used to understand these gradients. Microscopy has provided many important breakthroughs in our understanding of the fundamental biology, but is limited due to the need to incorporate fluorescent molecules into biological systems. As a result, there is a need to develop tools that can measure chemical gradient formation in biological systems that do not require fluorescent modification of the targets in question, can be multiplexed to measure more than one molecule and is compatible with a variety of biological sample types, including in vitro cell cultures and ex vivo tissue slices. Work from our group on the development of microfluidic tools to measure chemical gradients in living tissue will be presented. Two separate systems are under development. The first is a microfluidic system designed to analyze metabolite and protein expression from tissue. The sampling system can resolve up to 19 different ports and can be interface with either electrochemical or fluorescence-based detection methods. Using these two detection methods, we are capable of analyzing the release of either small molecule metabolites or proteins and peptides using immunoassays. The second system uses a high-density electrode array to image release of electrochemically active metabolites like nitric oxide from live tissue slices. Electrochemical characterization of this system combined with a microfluidic system for gradient generation will be shown.