Potentiometric (bioselective electrodes) assay systems: utility and limitations.

Numerous potentiometric assays utilizing bioselective electrodes are fast revolutionizing many areas of biotechnology. Adequately discussing the utility and limitations of these electrochemical systems is the purpose of this review. A general overview introduces bioselective potentiometry by presenting basic concepts, historical background, and current developments. Essentially, the review consists of several sections describing electrode architecture, operational concepts, different biosensors, assay systems, applications, and future trends. Advantages and disadvantages of the different bioselective assay systems discussed are included throughout each section. Electrode design discussion covers conventional liquid probes and the newer solid-state transitor biosensors. Limitations and advantages of different chemoreceptors, biocatalysts, and potentiometric transducers are presented. Operational characteristics include: linear behavior, sensitivity, stability, specificity, response, recovery, and the influence of interfering factors. Enzyme, organelle, tissue, and microbial biocatalytic sensors are discussed. Bioligand systems include: affinity, immunoselective enzyme, and liposome sensors. Potentiometric bioselective drug, microbial, and immunoassay systems are also included.