Molecular engineered graphitic carbon nitride with strong and stable electrochemiluminescence for immunosensing

Abstract

Graphitic carbon nitride (g-CN) is a semiconductor polymer with strong electrochemiluminescence (ECL) emission. However, the sensing application of g-CN ECL suffers from poor ECL stability due to its low electrical conductivity. In this work, g-CN is molecularly engineered with phenyl groups to improve its electrical conductivity. The prepared Ph-CN nanosheets (Ph-CNNS) show stable and strong cathodic ECL emission benefiting from the synergetic effect of improved conductivity preventing electron over-injection and higher luminescent efficiency of Ph-CNNS as compared to CNNS. Based on the strong and stable ECL emission of Ph-CNNS, a ECL immunosensor with biocatalytic precipitation reaction-mediated signal amplification is developed for the detection of cardiac Troponin I (cTnI), a biomarker of acute myocardium infarction. The ECL immunosensor shows a linear response to cTnI in the concentration range of 1 pg mL−1 ∼ 10 ng mL−1 with a detection limit of 0.5 pg mL−1, and exhibits good specificity, reproducibility and long-term stability. The ECL immunosensor is further used for the detection of cTnI in human serum sample. The good recovery suggests its feasibility in clinical application. This work provides a facile molecular engineering strategy to modulate g-CN ECL property, and would promote g-CN ECL in sensing application.