Nanocapillary electrophoretic electrochemical chip: towards analysis of biochemicals released by single cells.

A novel nanocapillary electrophoretic electrochemical (Nano-CEEC) chip has been developed to demonstrate the possibility of zeptomole-level detection of neurotransmitters released from single living cells. The chip integrates three subunits to collect and concentrate scarce neurotransmitters released from single PC-12 cells, including a pair of targeting electrodes for single cells captured by controlling the surface charge density; a dual-asymmetry electrokinetic flow device for sample collection, pre-concentration and separation in a nanochannel; and an online electrochemical detector for zeptomole-level sample detection. This Nano-CEEC chip integrates a polydimethylsiloxane microchannel for cell sampling and biomolecule separation and a silicon dioxide nanochannel for sample pre-concentration and amperometric detection.

Dual-asymmetry electrokinetic flow focusing for pre-concentration and analysis of catecholamines in CE electrochemical nanochannels.

In this research, a technique incorporating dual-asymmetry electrokinetic flow (DAEKF) was applied to a nanoCE electrochemical device for the pre-concentration and detection of catecholamines. The DAEKF was constructed by first generating a zeta-potential difference between the top and bottom walls, which had been pre-treated with O2 and H2O surface plasma, respectively, yielding a 2-D gradient shear flow across the channel depth. The shear flow was then exposed to a varying zeta-potential along the downstream direction by control of the field-effect in order to cause downward rotational flow in the channel.