Novel electroactive ferrocene-based covalent organic frameworks towards electrochemical label-free aptasensors for the detection of Cardiac Troponin I

The rapid and accurate determination of Cardiac troponin I (cTnI) has become more and more important to decrease the mortality of acute myocardial infarction (AMI). Herein, signal-on electrochemical aptasensors were fabricated for the sensitive and label-free determination of cTnI by combining the physical and electrochemical properties of ferrocene-based covalent organic framework nanosheets (Fc-COFNs). The novel Fc-COFNs were prepared via the facile condensation of 2,3,6,7,10,11-triphenylenehexol (HHTP) with 1,1′-ferrocenediboronic acid (BFc) through the formation of boronate esters. Upon covalent assembly of Fc-COFNs on a gold electrode using p-mercaptophenylboric acid (MBA) as scaffolds, the electrode exhibited excellent voltammetric response from the Fc moiety; while the electrochemical signal decreased significantly after the Fc-COFNs surfaces are shielded with aptamer strands. The bioaffinity of the target cTnI with the aptamer strands removed aptamers from the Fc-COFNs surfaces, giving rise the recovery of the electrochemical signal. The biosensors showed an ultra-low detection limit of 2.6 fg mL−1 with a linear range from 10 fg mL−1 to 10 ng mL−1 for cTnI. The practical applications of the aptasensors were evaluated by the spiking serum assay method.