ABSTRACT
Communication between cellular organisms mostly occurs through the release of specic biochemical or chemical messengers from an emitting cell to a receiving cell. In a practical view, analytical detection of such a release in real time can be particularly difcult since an innitely minute number of molecules are generally released during a brief fraction of time (milliseconds to seconds). By mimicking the advantages of the chemical synapse involved during neural communication, electrochemical techniques using ultramicroelectrodes (UMEs) represent a convenient way of bypassing this problem through the artificial synapse conguration (Figure 12.1). In practice, the UME is positioned in the close vicinity (a few hundreds of nanometers) of the investigated single-cell organism (Figure 12.1). Provided that a fraction of the content released by the cell is electroactive, intrinsic properties of UMEs as well as the experimental conguration itself allow one to electrochemically monitor (chronoamperometry, fast-scan cyclic voltammetry [FSCV]) the cell release with an excellent signal-to-noise (S/N) ratio and temporal resolution (see Section 12.1.2). Indeed, UME properties perfectly match the analytical requirements for an accurate electrochemical detection
12.1 Introduction: Micro versus Ultramicro Nanoelectrode ........................................................ 439 12.1.1 Electrochemical Properties of UMEs and Articial Synapse Conguration .......... 439 12.1.2 What Is a UME? ....................................................................................................... 441
12.2 Electrochemical Detection at the Single-Cell Level ............................................................ 443 12.2.1 Using a Basic UME .................................................................................................. 443
12.2.1.1 Detection of Exocytosis ............................................................................. 443 12.2.1.2 Detection of Oxidative Stress ....................................................................447
