Magnetron sputtered diamond-like carbon microelectrodes for on-chip measurement of quantal catecholamine release from cells

Biomed Microdevices. 2008 Oct;10(5):623-9. doi: 10.1007/s10544-008-9173-8.


Carbon electrodes are widely used in electrochemistry due to their low cost, wide potential window, and low and stable background noise. Carbon-fiber electrodes (CFE) are commonly used to electrochemically measure "quantal" catecholamine release via exocytosis from individual cells, but it is difficult to integrate CFEs into lab-on-a-chip devices. Here we report the development of nitrogen doped diamond-like carbon (DLC:N) microelectrodes on a chip to monitor quantal release of catecholamines from cells. Advantages of DLC:N microelectrodes are that they are batch producible at low cost, and are harder and more durable than graphite films. The DLC:N microelectrodes were prepared by a magnetron sputtering process with nitrogen doping. The 30 microm by 40 microm DLC:N microelectrodes were patterned onto microscope glass slides by photolithography and lift-off technology. The properties of the DLC:N microelectrodes were characterized by AFM, Raman spectroscopy and cyclic voltammetry. Quantal catecholamine release was recorded amperometrically from bovine adrenal chromaffin cells on the DLC:N microelectrodes. Amperometric spikes due to quantal release of catecholamines were similar in amplitude and area as those recorded using CFEs and the background current and noise levels of microchip DLC:N electrodes were also comparable to CFEs. Therefore, DLC:N microelectrodes are suitable for microchip-based high-throughput measurement of quantal exocytosis with applications in basic research, drug discovery and cell-based biosensors.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adrenal Glands / cytology
  • Animals
  • Carbon / chemistry
  • Carbon Fiber
  • Catecholamines / analysis*
  • Catecholamines / metabolism
  • Cattle
  • Cell Culture Techniques
  • Cells, Cultured
  • Chromaffin Cells / cytology
  • Chromaffin Cells / metabolism*
  • Diamond / chemistry
  • Dimethylpolysiloxanes / chemistry
  • Electrochemistry
  • Equipment Design
  • Exocytosis
  • Glass / chemistry
  • Lab-On-A-Chip Devices
  • Microchemistry / methods
  • Microchip Analytical Procedures / methods*
  • Microelectrodes
  • Microscopy, Atomic Force
  • Patch-Clamp Techniques
  • Spectrum Analysis, Raman
  • Substrate Specificity


  • Carbon Fiber
  • Catecholamines
  • Dimethylpolysiloxanes
  • baysilon
  • Carbon
  • Diamond