Integrating Highly Efficient Recognition and Signal Transition of g-C3N4 Embellished Ti3C2 MXene Hybrid Nanosheets for Electrogenerated Chemiluminescence Analysis of Protein Kinase Activity

Herein, a novel electrogenerated chemiluminescence (ECL) method for highly sensitive kinase activity and inhibitors screening was developed based on graphitic carbon nitride nanosheet (g-C3N4) nanoparticle embellished titanium carbide (Ti3C2) MXene nanosheets, integrating the highly efficient recognition and signal amplification activity. In this strategy, kemptide was first immobilized onto a gold electrode, and it was phosphorylated by the protein kinase A which was used as a model. The g-C3N4-MXene probe can adsorb explicitly onto the electrode based on chelation between the phosphate group and Ti defect sites enriched in MXenes. Besides the abundant active sites on MXene for the highly efficient binding with phosphate groups, the Ti3C2 MXene not only provides a unique conductive platform to accommodate more g-C3N4 nanoparticles but also facilitates the electron transfer on the electrode interface and suppresses the passivation of g-C3N4 that explores their highly efficient ECL emission with high stability. The obtained ECL signals were closely related to the kinase activity and can be applied for protein kinase A (PKA) activity detection. Under the optimal conditions, the proposed ECL biosensor provided a quantitative readout to PKA concentration in the range 0.015-40 U mL(-1) with the detection limit of 1.0 mU mL(-1). The ECL biosensor was also successfully applied to monitor drug-triggered kinase activation and quantitative analysis of the kinase inhibitors in MCF-7 cell lysates. This work shows that the proposed ECL biosensor has the potential to be a powerful tool for PKA study and clinical diagnostics as well as the discovery of new targeted drugs.