Electrochemical immunosensor for determination of cardiac troponin I using two-dimensional metal-organic framework/FeO-COOH nanosheet composites loaded with thionine and pCTAB/DES modified electrode.

Cardiac troponin-I (CTnI) is one of the most popular biomarkers which can be utilized for the diagnosis and control of acute myocardial infarction in clinical practice. Here, a sandwich-type electrochemical immunosensor has been established using the zinc-based metal-organic framework/FeO-COOH/thionine labeled anti-CTnI monoclonal antibody (Ab-Zn-MOF/FeO-COOH/Thi) nanocomposite as signaling molecule and a polymer film of cetyltrimethylammonium bromide (pCTAB) in the presence of choline chloride-urea deep eutectic solvent (DES) and anti-CTnI polyclonal antibody (Ab) as immobilization substance of detecting surface. The porous ultrathin layers of Zn-MOF nanosheets successfully prepare a well-defined structure for FeO-COOH electrocatalyst and Thi within a certain two dimensional (2D) regions, which enhances electrochemical reduction of Thi. The Ab-Zn-MOF/FeO-COOH/Thi nanocomposites were introduced to CTnI in the specimen and on the surface of pCTAB/DES-Au-SPE quantitative determination of CTnI was achieved using differential pulse voltammetry after sandwiching the CTnI target between Ab-nanocomposite and Ab which was encapsulated into the pCTAB/DES-Au-SPE. This immunosensor indicated the appropriate assay performance for CTnI with the detection range of 0.04 ng mL to 50 ng mL and the limit of detection of 0.0009 ng mL. This study provides convenient plan for sensitive detection of bioanalytes and opens a path for the establishment of user-friendly and cost-effective device.