Hollow graphitic carbon nitride with tunable shell thickness for electrochemiluminescence and photoelectrochemistry dual-mode detection of cardiac troponin I

An electrochemiluminescence (ECL) and photoelectrochemistry (PEC) dual-mode immunosensor based on hollow graphitic carbon nitride (H-C3N4) as dual-signal indicator was constructed for sensitive and accurate detection of cardiac troponin I (cTnI). Studied have been demonstrated that hollow structures rather than bulk nanomaterials can be able to decrease the inner filter effect and reduce the migration of photogenerated charges. Herein, we precisely control the shell thickness of H-C3N4 from 15.3 to 34.7 nm and clearly explore their correlating ECL-PEC performances. Notably, ECL and PEC performances of the optimal shell thickness of H-C3N4 (25.1 nm) is 2.7 and 4.4 times higher than that of solid C3N4, which leaves enormous room for optimization the performances of H-C3N4. Furthermore, TiO2 not only is a coreaction accelerator, but also possesses well-matched band structure with H-C3N4. By integrating TiO2 with the optimal H-C3N4, the obtained H-C3N4@TiO2 shows the highest ECL and PEC response. As a result, the established immunosensor shows the sensitive detection of cTnI with a desirable detection limit of 0.65 fg mL−1 (ECL) and 0.63 fg mL−1 (PEC), respectively. This work shows an effective strategy to develop a dual-mode immunosensor which allows signal cross-checking and presents a reliability detection in bioanalysis.