Abstract

Biological Imaging Using Microfluidics and Electrochemistry

Charles Henry, Professor and Chair, Colorado State University

Chemical gradients drive many processes in biology, ranging from nerve signal transduction to ovulation to cancer metastasis. At present, microscopy is the primary tool used to understand these gradients by imaging both the gradients and the resulting cell motion. Microscopy has provided many important breakthroughs in our understanding of fundamental biology, but is limited due to the need to incorporate fluorescent molecules into biological systems through either labeling or genetic manipulations. To better understand some processes, 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, can be multiplexed to measure more than one molecule, and are compatible with a variety of biological sample types, including in vitro cell cultures and ex vivo tissue slices. In response to this need, we have developed a high-density electrode array containing 8,192 individual electrodes to image release of electrochemically active metabolites like nitric oxide and norepinephrine from live tissue slices. The electrode array has a resolution of 30 µm and covers and area of 2 mm by 2 mm, easily large enough to image release of neurotransmitters across an ex vivo tissue slice from a mouse model. In this talk, electrochemical characterization of this system will be discussed first using simple chemical models. Then use of the system in combination with microfluidics, for imaging spatiotemporal resolution of neurotransmitter release at the organ scale will be presented. Use of microfluidics to deliver stimulants that induce changes in release profile will be shown.