ABSTRACT
The biotechnological aspects of scanning electrochemical microscopy (SECM) that are discussed in this chapter comprise those systems in which the biochemical function of the molecules is an important part of the imaging mechanism. SECM experiments utilizing enzymes, antibodies and nucleic acids are considered. The merits of generation-collection and feedback (FB) strategies for imaging enzyme activity are described in detail because of their importance for biosensing and immunoassay. In general, FB modes provide higher spatial resolution, but generation-collection modes give low detection limits because of the absence of a background current. Antibody-antigen reactions are studied using labeling techniques, often using enzyme amplification. Nucleic acids may also be imaged using redox and enzyme labels; however, the high charge density of DNA films also allows novel techniques based on the Donnan exclusion of charged redox probes from the films. In addition to the imaging mechanism, methods for independent calibration of tip-to-substrate distance based on oxygen reduction, impedance, mechanical damping and ion conductance techniques are described. The constraints on imaging speed, resolution and detection limit are analyzed quantitatively and the chapter concludes with an outlook on the future of the field.
