Dual-Quenching Electrochemiluminescence Strategy Based on Three-Dimensional Metal-Organic Frameworks for Ultrasensitive Detection of Amyloid-β

We have proposed a dual-quenching electrochemiluminescence (ECL) strategy which is based on tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] as chromophores caged in three-dimensional (3D) zinc oxalate metal-organic frameworks [Ru(bpy)3(2+)/zinc oxalate MOFs] for ultrasensitive detection of amyloid-beta (A beta). The three-dimensional chromophore connectivity in zinc oxalate MOFs provided a network for rapid excited-state energy transfer migration among Ru(bpy)(3)(2+) units which shielded the chromophores from solvent molecules and led to a high-energy Ru emission efficiency. In addition, we found that both Au nanoparticles and NiFe-based nanocube MOFs could contribute to the reduction of the ECL intensity of the chromophore. The ECL emission spectra of 3D Ru(bpy)(3)(2+)/zinc oxalate MOFs overlapped appropriately with the ultraviolet-visible (UV-vis) absorption spectra of Au@NiFe MOFs composites, which could trigger the resonance energy transfer (RET) behavior between Ru(bpy)(3)(2+)/zinc oxalate MOFs (donor) and Au@NiFe MOFs the sensitivity of the A beta detection immunosensor. In order to examine the clinical practicability, we have applied it to verify the content of A beta solution ranging from 100 fg mL(-1) to 50 ng mL(-1) and obtained the calibration curve with high correlation coefficient, along with the low limit of detection of 13.8 fg mL(-1). Above all, this work demonstrated an approach of constructing dual-quenching effect ECL immunosensors in whole 3D MOF systems and its application in ECL detection methodology.