Nanoelectrode ensemble immunosensor platform for the anodic detection of anti-tissue transglutaminase isotype IgA

Abstract

• Immunosensor for IgA anti-tTG is developed using nanoelectrode ensemble. • Sec-antibody with glucose oxidase and ferrocenyl mediator allow anodic detection. • Detection limit is 3 times lower than previous electrochemical immunosensors. • Immunosensor and fluroenzyme assay in celiac patients show satisfactory agreement. A nanostructured electrochemical sensors is developed to detect IgA isotypes of anti-tissue transglutaminase (anti-tTG) by recording an anodic electrocatalytic current. To this aim, nanoelectrode ensembles (NEEs) prepared by electroless gold deposition on track-etched polycarbonate, are at first functionalized with tissue transglutaminase (tTG) to capture anti-tTG from serum samples. In the following step, the selective detection of the IgA isotype of anti-tTG is performed by reacting with anti-IgA secondary antibody labelled with glucose oxidase. In case of positive response, the addition of glucose (substrate) and (ferrocenylmethyl)trimethylammonium (redox mediator), produces an electrocatalytic anodic current which scales with the IgA anti-tTG concentration. The optimized immunosensor provides low detection limit (0.7 U mL −1 ), can be applied in serum samples diluted with buffer solution and show to be suitable for quantifying IgA isotype of anti-tTG in human serum samples from celiac patients.