Nanoelectrodes: Applications in electrocatalysis, single-cell analysis and high-resolution electrochemical imaging

• High sensitivity and high spatial resolution in localized electrochemical measurements are the key advantages of electroanalysis using nanometer-sized electrodes.
• Different protocols for the fabrication of needle-type nanoelectrodes are summarized.
• Limits of conventional theory to describe electrochemistry at the nanoscale are discussed.
• Different applications of nanoelectrodes are highlighted including non-ensemble studies of electrocatalysis at single nanoparticles at high mass transport rates, electrochemical nanosensors for highly localized non-invasive analysis of single living cells and intracellular detection of neurotransmitters and metabolites as well as the use of nanoelectrodes in scanning electrochemical probe techniques.

High sensitivity and high spatial resolution in localized electrochemical measurements are the key advantages of electroanalysis using nanometer-sized electrodes. Due to recent progress in nanoelectrode fabrication and electrochemical instrument development, nanoelectrochemical methods are becoming more widespread. We summarize different protocols for the fabrication of needle-type nanoelectrodes and discuss their properties with regard to various applications. We discuss the limits of conventional theory to describe electrochemistry at the nanoscale and point out technical aspects for characterization and handling of nanometric electrodes. Different applications are highlighted: i) Nanoelectrodes are powerful tools for non-ensemble studies of electrocatalysis at single nanoparticles at high mass transport rates. ii) Electrochemical nanosensors are employed for highly localized non-invasive analysis of single living cells and intracellular detection of neurotransmitters and metabolites. iii) Used in scanning electrochemical probe techniques, nanoprobes afford topographical and truly chemical imaging of samples with high spatial resolution.