A novel microfabricated device measures a large fraction of hormone release from individual-cells with high time resolution

Single-cell assays of hormone or neurotransmitter secretion have applications in cell-based biosensor development, high-throughput screening of drugs and basic science investigations. We are using microsystems technology to make electrochemical electrodes in picoliter-size wells for measuring catecholamine release from. individual cells. By making the well-electrode only slightly larger than the cell, high sensitivity and time resolution are achieved. The electrode can detect "spikes" of oxidative current corresponding to the release of individual catecholamine-containing vesicles from bovine adrenal chromaffin cells with millisecond time resolution. In, addition, we have simultaneously used whole-cell patch clamp recording to estimate that more than 60% of catecholamine released from the cell is captured by the well-electrode.