High-Efficiency CNNS@NH2-MIL(Fe) Electrochemiluminescence Emitters Coupled with Ti3C2 Nanosheets as a Matrix for a Highly Sensitive Cardiac Troponin I Assay

Synthesis of a highly efficient electrochemiluminescence (ECL) luminescent material is one of the effective means to improve the sensitivity of the sensor. In this study, an efficient ECL luminescent nanomaterial, carbon nitride nanosheet (CNNS) decorated amino-functional metal–organic frameworks (CNNS@NH 2 -MIL(Fe)) were synthesized for sensitive ECL detection of cardiac troponin I (cTn-I). The synthesized CNNS@NH 2 -MIL(Fe) realized the effective mass loading of CNNS, and more importantly, the NH 2 -MIL(Fe) could expedite the reduction of coreactant S 2 O 8 2– to produce abundant ECL reaction intermediate SO 4 •– near CNNS, thus, shortening the distance between SO 4 •– and the excited state of CNNS with less energy loss to extremely enhance the ECL signal of CNNS. Furthermore, the ECL signal of the immunosensor could be further enhanced when the Ti 3 C 2 nanosheet was used as the matrix to capture primary anti-cTn-I due to the reason that Ti 3 C 2 not only exhibited a large surface area and excellent metallic conductivity, but also could act as a coreaction accelerator to speed up the reduction of S 2 O 8 2– with plenty of SO 4 •– generated. Therefore, this proposed ECL immunosensor using CNNS@NH 2 -MIL(Fe) as a signal probe and Ti 3 C 2 as a sensing matrix exhibited a significantly enhanced ECL signal and had a high sensitivity and excellent selectivity for cTn-I. Consequently, this multiple signal amplification strategy provided an effective method for trace protein ultrasensitive detection in ECL bioanalysis.