Intracellular voltammetry

Meulemans, A., Poulain, B., Baux, G., Tau, L., HenzeL D. Micro carbon electrode for intracellular voltammetry. Anal. Chem. 1986, 58, 2088—2091. 

Nanoprobes for intracellular voltammetry can be made with the commercially available sophisticated laser pullers. However, there are difficulties needed to be overcome. Like intracellular redox moieties are apparently localized and cannot... 

INTRACELLULAR VOLTAMMETRY WITH ULTRASMALL CARBON RING ELECTRODES... 

Carbon ring electrodes with structurally ultrasmall tip diameters were fabricated as described elsewhere. Electrodes with 3-5 pm tip diameters were used for intracellular voltammetry. Electrodes used for characterization ranged from 3 to 15 im in tip diameter. 

Intracellular Voltammetry with Ultrasmall Carbon Ring Electrodes... 

Recently new methods, based on petturbations on the linear sweep voltammetry response of the mediator in the presence of the protein," a mediated thin-layer voltammetry technique, cyclic voltammetric simulation apphed to an electrochemically mediated enzyme reaction" have been setded to gain information on the protein-mediator interactions. More recendy the Scanning Electrochemical Microscopy (SECM) was used to probe the red-ox activity of individual cells of purple bacteria, by using two groups of mediators (hydrophilic and hydrophobic species) in order to gain information on the dependence of measured rate constant on the formal potential of the mediator in solution. By this technique an evaluation of the intracellular potential was also performed. ... 

Early studies by Meulemans et al. used differential pulse voltammetry (see Chapter 11) to measure the concentration of electroactive drugs in the cytoplasm of cholinergic neurons of Aplysia californica and to determine rates of cellular uptake and clearance (108). Another report by Meulemans et al. described a needle tipped glass insulated platinum electrode for detection of intracellular serotonin in metacerebral neurons from Aplysia (109). Again differential pulse voltammetry was used to measure intracellular concentration of serotonin after cell stimulation, after injection of serotonin into the cell, and after extracellular treatment with tryptophan, a serotonin precursor. Serotonin concentration in resting untreated cells was determined to be 0.94 0.61 mM. Chen et al. have also used platinum electrodes with multiple pulse voltammetry to measure dopamine levels in the giant dopamine neuron of Planorbis comeus (110). 

The other intracellular voltammetric method worked out is applicable for measurement of transport rates across cell membranes. For this the cell is attached on gold substrate. The working electrode is positioned inside the cell over the section of the membrane which adheres to the gold surface. The regeneration of the mediator at the gold surface is faster and less complicated. Therefore the positive feedback current is less affected by a slow intracellular redox reaction that can be the case if the transport rate is tested by extracellular voltammetry. 

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