Study of cell secretion using MEMS-based arrays

This paper focuses on the development of a custom MEMS-based array which will facilitate cell secretion studies by enabling parallel electrochemical detection of secretion events from separate cells with millisecond resolution. Initial prototypes of the microarrays have been fabricated with well-shaped gold electrodes which roughly conform to the shape of a single cell. Amperometric measurements on bovine adrenal chromaffin cells using the prototype microarrays concluded that 80% of the catecholamine secreted from the cells was captured by the well-electrodes. This was a 4-fold increase in detection efficiency over the conventional carbon fiber electrode method. To expand the applicability of this method, additional cell-lines and microarray designs are under investigation. An amphibian fibroblast cell-line (FT cell-line, American Tissue Culture Collection) is being used in our lab. FT cells can take up hormones or other biological compounds from the culture media through a non-specific uptake mechanism which is still under investigation. Microarrays of a new design have been fabricated with patterned gold electrodes on polyimide. A different testing method will be applied to these new microarrays. The FT cells will be cultured directly on top of the microarrays to cover the gold electrodes. Cells will then be loaded with norepinephrine by incubation in media containing 1mM norepinephrine. Rapid elevation of intracellular Ca2+ levels triggers the exocytosis of norepinephrine which then can be detected by the gold electrode. The new polyimide based microarrays have been successfully used to support confluent growth of the FT cells. Loading of the FT cells with norepinephrine and electrochemical detection tests are underway.