Biomedical Engineering Reference
In-Depth Information
Figure 10. Schematic diagram of an SECM experiment with a single cell. (A) The
tip is positioned in the solution close to the cell surface. Positive feedback is due to
bimolecular electron transfer between the hydrophic redox mediator (O/R) and cell-
bound redox moieties (O2/R2). (B) The lipid cell membrane is impermeable for a
hydrophilic redox mediator. Negative feedback is due to the hindered diffusion of
redox species to the tip electrode. (C) Nanoelectrode voltammetry inside the cell.
(D) Positive feedback is produced by mediator regeneration by way of electron
transfer at the underlying Au surface. Reproduced with permission from Ref. 216,
Copyright (2008) National Academy of Sciences, U.S.A.
structures into cells with a subsequent electrical measurement af-
fect the cellular functions.
Heller et al. took a different, non-invasive approach to probe
cellular electrochemical activity. By coating a suspended single-
walled carbon nanotube electrochemical (electrolyte-gated) FET
device with antibodies, they were able to persuade macrophage
cells to ingest (engulf) the nanotube. After positioning an individ-
ual cell over the device, both FET and electrochemical signals as-
sociated with cellular activity were separately detected. When the
carbon nanotube was coated with Pt nanoparticles, sharp bursts of
current due to electrocatalytic reduction of reactive oxygen and
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