Metal-organic Frameworks (MOF)-based Novel Electrochemiluminescence Biosensing Platform for Quantification of H2O2 Releasing from Tumor Cells

In this work, a kind of high-performance electrochemiluminescence (ECL) material was obtained with the assistant of metal-organic framework (MOF) structure, which realized the highly ordered assembly of ECL molecules in MOF structure, developing a new strategy of synergistically enhanced ECL. Specifically, it combined the advantages of both the pore confinement effect and the highly ordered assembly of ECL molecules in micro/nano space to enhance the ECL intensity and reaction efficiency. The proposed MOF material (abbreviated as Zr-TCPE) with excellent ECL performance was synthesized by a simple solvothermal synthesis technique employing the non-coplanar molecule 1,1,2,2-tetrachlorophenol(4-carboxylic benzene)ethylene (H4TCPE) as ligand and Zr-6 clusters through coordination interaction. Zr-TCPE with the porous structure can not only promote the mass transport and electron transfer in the confined micro/nano spaces, but also reduce the nonradiative relaxation and filtering effect as the H4TCPE ligands were fixed on the rigid metal frame, restricting the free vibration/rotation and tight packing. Compared with the H4TCPE micro/nano crystals prepared by reprecipitation method, the ECL intensity and efficiency of the Zr-TCPE increased by 3.46 times and 17.44 times with potential from 0 V to 1.4 V at 300 mV/s in 2 mL of detection solution (containing 18 mmol/L triethylamine, pH 7.4), respectively. The ECL biosensor was constructed according to the successive assembly of (i) the Zr-TCPE as ECL material, (ii) silver nanoparticles (Ag NPs) as immobilization matrix of concanavalin A (Con A) and (iii) the Con A as a cells trapping agent. which achieved the in situ monitoring of hydrogen peroxide (H2O2) released from the tumor cells under the stimulative effect of phorbol 12-myristate 13-acetate (PMA). Furthermore, the ECL biosensor could rapidly distinguish cancer cells from nonnal cells. What is more, the ECL biosensor is also suitable for the detection of H2O2 released from the various tumor cells. The prepared Zr-TCPE, as the combination of strong ECL emission, easy preparation and good biocompatibility, was expected to be a kind of popular luminophors for the clinical detection of tumor cells.