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

Abstract

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. The cell-capture voltage ranges from 0.1 to 1.5 V with a frequency of 1-10 kHz for PC-12 cells, and the single cell-capture efficiency is optimized by varying the duration of the applied field. All of the processes, from cell sampling to neurotransmitter detection, can be completed within 15 min. Catecholamines, including dopamine and norepinephrine (noradrenaline) released from coupled single cells, have been successfully detected using the Nano-CEEC chip. A detection limit of 30-75 zeptomoles was achieved, which is close to the levels released by a single neuron in vitro.

Current Trends of Microfluidic Single-Cell Technologies

“…Another technique developed by Wu et al [ 221 ] is capable of zeptomole-level detection of neurotransmitters released from single living cells using nanocapillary electrophoretic electrochemical (Nano-CEEC) chips. The chip is comprised of three units, a pair of targeting electrodes for capturing single-cells, a dual asymmetry electrokinetic flow device for sample collection, pre-concentration and separation, and an amperometric sensor for the detection and analysis of neurotransmitters.…”

“… Schematic representation of a Nano-CEEC chip designed for living single-cell analysis. Step 1: ( a ) cell loading, capturing and culturing in the cell chamber; Step 2: ( b1 , b2 ) DAEKF (dual-asymmetry electrokinetic flow) separation, including sample collection, nanoseparation and restacking in the nanochannel; Step 3: ( c ) amperometric detection by the EC detection electrodes; ( d ) Schematics showing the flow-field evolution for DAEKF electrophoresis manipulated by surface zeta potentials in the nanochannel (solid arrows represent the analyte flow direction) Reproduced from [ 221 ] with permission of The Royal Society. …”

Ultra-thin flexible polyimide neural probe embedded in a dissolvable maltose-coated microneedle

“…Activated iridium oxide demonstrates excellent charge transfer properties, but its surface is chemically unstable [59]. However, the technique of coating carbon nanotubes (CNTs) on electrodes has been demonstrated to not only decrease impedance and increase charge transfer, but also offer satisfactory stability for longterm brain-machine interface devices [60][61][62].…”

Nanoengineering life: from cell to tissue

“…Although single-cell detection technique is highly desirable [5], it has only been realized recently thanks to the advancement of nanofabrication and micro-/nano-fluidic systems. In this special issue, Wu et al [6] report a novel nano capillary electrophoresis electrochemical chip (Nano-CEEC) integrating with micro-/nano-fluidic components to collect and concentrate scarce neurotransmitters released from single cells in vivo. Such a device provides a novel technological platform for future single cell-cell interaction measurement as well as single cellular functional monitoring.…”