Two-Dimensional Metalloporphyrinic Framework Nanosheet-Based Dual-Mechanism-Driven Ratiometric Electrochemiluminescent Biosensing of Protein Kinase Activity

A dual-mechanism-driven ratiometric electrochemiluminescent (ECL) biosensor was developed for the ultrasensitive detection of protein kinase activity, which was based on a competitive catalytic reaction and resonance energy transfer (RET) by assembling gold nanoparticles (GNPs) on two-dimensional (2D) porphyrinic metal–organic framework (MOF) nanosheets. In this work, an ECL catalytic reaction competing for dissolved O₂ proceeded between 2D copper-based zinc porphyrinic MOF (Cu–TCPP­(Zn)) nanosheets and luminol. Meanwhile, the cathodic ECL of singlet oxygen (¹O₂), derived from the electrocatalytic reaction of 2D Cu–TCPP­(Zn), would be reduced by the assembled GNPs due to RET, while the anodic emission of luminol could be enhanced by GNPs with excellent electrocatalytic activity. With the detection of protein kinase A (PKA) as an example, this dual-mechanism-driven ECL biosensor exhibited a broad linear range (0.005–5.0 U mL^–1) and a sensitive detection limit (0.0037 U mL^–1). Compared with the traditional single-mechanism-driven sensing strategies, the developed dual-mechanism-driven ratiometric ECL biosensor may provide an effective method for the design of green and ultrasensitive ECL sensors.