Zirconium–Metalloporphyrin Frameworks–Luminol Competitive Electrochemiluminescence for Ratiometric Detection of Polynucleotide Kinase Activity

Abstract

We propose a novel competitive mechanism involving the dissolved oxygen (O₂) between zirconium-based porphyrinic metal-organic framework nanoparticles (NMOFs) and luminol into a ratiometric electrochemiluminescence (ECL) biosensing interface. Zinc tetrakis(carboxyphenyl)-porphyrin (ZnTCPP) in NMOFs as electron media reduce O₂ into reactive oxygen species (ROS) and produce singlet oxygen (¹O₂), resulting in cathodic ECL. Meanwhile, ROS also react with the luminol anion radical and amplify the anodic ECL emission. Based on the competitive-mechanism-driven ECL process, taking the detection of polynucleotide kinase (PNK) as example, with assembling DNA-functionalized NMOFs on the sensing interface, a lower detection limit of 6.5 × 10^-5 U mL^-1 and broader linear relationship range from 0.0002 to 10 U mL^-1 were obtained compared with that of single-signal-driven ECL sensors. This proposed MOFs-luminol competitive ECL mechanism involving dissolved O₂ may provide a new pathway for further research of a green and highly sensitive ECL biosensing system.