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

Abstract

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-β (Aβ). The threedimensional 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 (acceptor), achieving the dual-quenching effect of Ru(bpy) 3 2+ encapsulated in 3D zinc oxalate MOFs and significantly boosting the sensitivity of the Aβ detection immunosensor. In order to examine the clinical practicability, we have applied it to verify the content of Aβ 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.

Electrochemical Applications of Ferrocene‐Based Coordination Polymers

“…[83] In another work, an FcÀ Zn-MOF with flower-like morphology was synthesized via postsynthetic covalent bonding of a Zn-MOF and the electrochemically active Fc to construct an electrochemical signal tag for the highly sensitive detection of amyloid-β as a model protein. [84,85] The enhanced electrochemical activity of the FcÀ Zn-MOF was ascribed to the high content of Fc signal units regularly arranged in the porous structure ( Figure 7).…”

“…Postsynthetic modification was used to prepare an Fc‐modified MOF composite based on NH 2 ‐UiO‐66, namely trGNO/Fc‐NH 2 ‐UiO‐66, which was used for the ratiometric electrochemical detection of heavy metal ions [83] . In another work, an Fc−Zn‐MOF with flower‐like morphology was synthesized via postsynthetic covalent bonding of a Zn‐MOF and the electrochemically active Fc to construct an electrochemical signal tag for the highly sensitive detection of amyloid‐β as a model protein [84,85] . The enhanced electrochemical activity of the Fc−Zn‐MOF was ascribed to the high content of Fc signal units regularly arranged in the porous structure (Figure 7).…”

“…Heavy metals ions such as Pb(II), Cd(II), and Hg(II) are highly toxic components of wastewater and are mostly non‐biodegradable and bioaccumulative [159] . Furthermore, techniques for the simultaneous detection of these species, such as electrochemical detection methods, [73,84, 99] are highly sought after. The advantages of electrochemical sensors such as operation simplicity, high sensitivity, rapid response, and portability illustrate their high potential for real‐world applications, particularly for the simultaneous detection of multiple heavy metal ions [131] .…”

Single-Atom Nanozymes Linked Immunosorbent Assay for Sensitive Detection of A β 1-40: A Biomarker of Alzheimer’s Disease

“…Amyloid beta 1-40 (A β 1-40), as one of the most plentiful substances in humans, will easily form insoluble toxic A β 1-40 aggregation, which is a vital neuropathological hallmark to identify Alzheimer's disease commonly; the clinically relevant range of A β 1-40 is several ten to several hundred pg/mL [ 24 , 25 ]. It is well known that AD begins in the human body years before symptoms present, so detecting A β 1-40 at low concentration is of great importance and can be used to estimate the risk or show the presence of AD at early stage [ 26 – 28 ].…”

Synthesis, crystal structures, fluorescence, electrochemiluminescent properties, and Hirshfeld surface analysis of four Cu/Mn Schiff‐basecomplexes

“…The design and synthesis of novel coordination polymer (CP) materials with Schiff base as an organic ligand have been the hot topic of current research, [1][2][3] as they have wide applications in optics, [4][5][6] electromagnetism, [7][8][9] adsorption, [10] and catalysis. [11][12][13][14][15] Currently, the main coordination modes of Schiff bases are the coordination of metal ions with O and N. [16][17][18][19][20] Therefore, the choice of an organic ligand determines the nature of the CPs.…”