Scanning Electrochemical Microscopy as a Tool in Neuroscience

Excerpt

Scientists have proposed potentiometric SECM with ion-selective microelectrodes as scanning probes aimed at the determination of the local activity of a number of ions including protons, chloride, sodium, potassium, and calcium [60–65]. All of these ions are of physiological importance and, although not shown to date, assessing their local concentrations in vicinity of individual living cells with scanned H⁺ -, Na⁺ -, K⁺ -, Ca²⁺ - or Cl⁻ -selective tips could be attractive. However, this review focuses on the latest efforts in developing amperometric SECM into a high-resolution electrochemical imaging tool applicable for research and development in the field of neuroscience, with special emphasis given to the local amperometric detection of chemical secretion from single secretory cells. In order to help understand the method, this chapter will first introduce the relevant features of the amperometric microelectrodes and the basic operational principles and technical concept of SECM including the amperometric feedback and the generator collector mode of imaging.

Taking into account the fragile nature of soft living cells, this chapter will discuss the limitations of the ordinary constant-height mode of SECM and present approaches for establishing a constant-distance mode. Only by using SECM in constant-distance mode, the SECM tip is forced to carefully follow the contours of the cell throughout scanning to avoid damaging the tip and the investigated biological sample. Finally, this section will present selected examples of single-cell SECM studies, which highlight the potential impact of this modern electrochemical assay in neurochemistry.