ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉An ultrasensitive sandwich-type electrochemical immunosensor was developed for the amperometric determination of serum myeloperoxidase (MPO). The method is making use of (a) gold nanoparticles encapsulated in graphitized mesoporous carbons (AuNP@GMC); and (b) horseradish peroxidase (HRP) labeled secondary antibody (HRP@Ab〈sub〉2〈/sub〉) immobilized on AuNP@GMC. MPO capture antibody (Ab〈sub〉1〈/sub〉) was immobilized on the electrode modified with an AuNP-graphene oxide nanocomposite. The sandwich immunoreaction leads to the formation of the complex composed of Ab〈sub〉1〈/sub〉, MPO, and HRP@Ab〈sub〉2〈/sub〉. An amplified electrochemical signal is produced by electrocatalytic reduction of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 (at a typical voltage of −0.18 V vs. Ag/AgCl) in the presence of enzymatically oxidized thionine. The peak current of thionine was measured using differential pulse voltammetry. Under optimized steady-state conditions, the reduction peak increases in the 1 to 300 pg.mL〈sup〉−1〈/sup〉 MPO concentration range, and the detection limit is 0.1 pg.mL〈sup〉−1〈/sup〉 (at S/N = 3).〈/p〉 〈p〉 〈span〉 〈caption〉 〈strong〉Graphical abstract〈/strong〉 〈em〉 〈div〉Schematic presentation of AuNP-GO based sandwich-type electrochemical immunoassay for the determination of myeloperoxidase by using gold nanoparticles encapsulated in graphitized mesoporous carbons (AuNP@GMC) as a carrier for horseradish peroxidase (HRP) labeled secondary antibody (HRP@Ab〈sub〉2〈/sub〉)〈/div〉 〈/em〉 〈/caption〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/604_2019_3359_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉