Editors’ Choice—Review—From Polarography to Electrochemical Biosensors: The 100-Year Quest for Selectivity and Sensitivity

This is a story of the 100-year path for voltammetric electroanalytical chemistry from the serendipitous discovery of polarography by Jaroslav Heyrovsky in 1922 to the miniature biosensors of today. In spite of issues with the dropping mercury electrode (DME), polarography was dominant for almost 50 years due to the good quantitative results it produced. Then, significant developments led to today's methods with drastic improvements in detectable concentration and amount, selectivity, ease of use, and breadth of application. Important steps forward include the shift from the DME to solid electrodes, the strategic modification of electrode surfaces chemically and with membranes, electrochemistry in thin layers of solution with the associated decrease in sample amount from milliliters to microliters and below, liquid chromatography with electrochemical detection, more powerful and smaller instrumentation, microfabrication of electrodes, pulse techniques that improved concentration limits of detection by discriminating against double layer charging, spectroelectrochemistry for enhanced selectivity by electrochemically changing a spectroscopic signal, cyclic voltammetry for the general utility that makes it the work-horse of voltammetry, and biosensors that dramatically expanded the applicability of voltammetry through the use of nature's biological catalysts (enzymes) and capture agents (antibodies, aptamers).