Chemical or biochemical assay, involving electrochemically assessing a change in diffusion coefficient of redox-active species due to a specific binding reaction, useful e.g. for determining antigens or DNA fragments

摘要

A method for the determination of chemical or biochemical analytes (A) comprising modulating the diffusion coefficient of a redox-active species coupled with a specific recognition element by binding with a complementary recognition structure and electrochemically detecting the modulation of the diffusion coefficient, under amplification by recycling the redox species, is new. An Independent claim is also included for apparatus for carrying out the method, comprising an electrochemical measuring cell of volume 10 mu l to 1 ml (preferably less than 300 mu l) with a reference electrode, counter-electrode and macroscopic regeneration surface, in which a micro-electrode of active diameter 0.1-500 mu m can be positioned adjacent to the regeneration surface using positioning elements. In alternative forms of the apparatus: (a) the cell is formed by an array of measuring cells, especially of the microtiter plate type, the base of which forms a one combined or several separate conductive regeneration surfaces; (b) the cell has no walls contacting the reaction solution; or (c) several microelectrodes can be placed in parallel (using positioning elements) in several measuring cells or drops of the determination solution can be applied to each measuring surface, so that several samples can be tested simultaneously.