A redox-mediated chromogenic reaction and application in immunoassay

A novel redox-mediated chromogenic reaction was demonstrated based on the reaction between HAuCl 4 and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), which generate various color responses from red to green in the resulting solutions. Various redox substance could be used to mediate the reaction and trigger a distinct color response. We established a sensitive hydrogen peroxide colorimetric sensor based on the redox-mediated chromogenic reaction and depicted the application both in detection of enzyme and in an immunoassay . Combining the traditional chromogenic reagent with gold nanoparticles , our assay has the advantage in short response time (within three minutes), high sensitivity (10 −12  g mL −1 for HBsAg) and stability.