Abstract
This article describes the development of biosensors with electrochemically-amplified responses. In general, chemical amplification involves a reaction sequence for a substrate to generate a relatively large amount of the product. Thus a trace concentration of analyte can be caused to yield orders of magnitude higher product concentration which may be more easily be measured than the analyte itself. For electrochemical biosensors that detect biochemical reactions on the electrode surfaces, chemical amplification procedures suitable for concentrating the electroactive species near the electrode/test solution interface should be utilized to enhance the sensor response effectively. Thus the use of combination of bio-electrochemical processes such as catalytic reaction to regenerate electroactive species and adsorptive stripping procedure to accumulate electroactive species on electrode surfaces can be useful for realizing highly-sensitive biosensors. Actually, immunoassay protocol combined with such electrochemical amplification techniques has enabled us to determine biomarkers with picomolar-levels. Recently we have successfully applied particle manipulation based on dielectrophoresis to develop rapid and separation-free immunosensing systems. The union of highly-sensitive electrochemical detection and dielectrophoretic particle manipulation (or accumulation) would provide biosensor systems suitable for the purpose of the point-of-care testing of biomarkers.
