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.

石墨氮化碳 (g-CN) 是一种具有强电化学发光 (ECL) 发射的半导体聚合物。然而，g-CN ECL的传感应用由于其低电导率而存在ECL稳定性差的问题。在这项工作中，g-CN 用苯基进行分子工程以提高其导电性。与 CNNS 相比，制备的 Ph-CN 纳米片 (Ph-CNNS) 显示出稳定和强的阴极 ECL 发射，这得益于提高电导率防止电子过度注入的协同效应和更高的发光效率。基于Ph-CNNS强大而稳定的ECL发射，开发了一种具有生物催化沉淀反应介导的信号放大的ECL免疫传感器，用于检测心肌梗死的生物标志物心肌肌钙蛋白I（cTnI）。^-1 ∼ 10 ng mL ^-1，检出限为0.5 pg mL ^-1，具有良好的特异性、重现性和长期稳定性。ECL 免疫传感器进一步用于检测人血清样品中的 cTnI。良好的恢复表明其在临床应用中的可行性。该工作为调节g-CN ECL特性提供了一种简便的分子工程策略，并将促进g-CN ECL在传感应用中的应用。