MOLECULAR RECOGNITION USING CONDUCTING POLYMERS - BASIS OF AN ELECTROCHEMICAL SENSING TECHNOLOGY

Molecular recognition principles are being increasingly used as the ba sis for analytical technologies. The combination of a molecular recogn ition approach with conducting polymer materials has been beneficial, particularly in the field of electrochemical sensing. The electrochemi cal sensing process usually consists of two steps: analyte recognition and signal generation. Conducting polymers are versatile materials in which molecular/analyte recognition can be achieved in a number of di fferent ways, including.the incorporation of counter ions that introdu ce selective interactions, using the inherent and unusual ion-exchange properties of the conducting polymers; the addition of functional gro ups to the monomers; and the codeposition of metals within the polymer . Specific examples of these approaches are provided. The molecular re cognition properties of conducting polymers can be further refined by the application of appropriate electrochemical potentials, which can i nduce either large or small changes in the chemical interactions that occur at the polymers. This electroactivity, as well as their conducti ng properties, also provides the basis for the signal generation steps . A number of electronic signals relating to some chemical or electroc hemical change within the polymer can be measured. These include the f aradaic electron transfer typically used for electrochemical sensing, the catalysis of the analytically useful electron transfer by the poly mer or the analyte, the change in capacitance signals induced by the a nalyte species and changes in the polymer resistance which can be meas ured by a recently developed technique. These features, combined with the molecular recognition properties, make conducting polymers a very promising material for electrochemical sensing technology.