Self-Luminescent Lanthanide Metal–Organic Frameworks as Signal Probes in Electrochemiluminescence Immunoassay

Abstract

The successful use of electrochemiluminescence (ECL) in immunoassay for clinical diagnosis requires development of novel ECL signal probes. Herein, we report lanthanide (Ln) metal−organic frameworks (LMOFs) as ECL signal emitters in the ECL immunoassay. The LMOFs were prepared from precursors containing Eu (III) ions and 5-boronoisophthalic acid (5-bop), which could be utilized to adjust optical properties. Investigations of ECL emission mechanisms revealed that 5-bop was excited with ultraviolet photons to generate a triplet-state, which then triggered Eu (III) ions for red emission. The electron-deficient boric acid decreased the energy-transfer efficiency from the triplet-state of 5-bop to Eu (III) ions; consequently, both were excited with highefficiency at single excitation. In addition, by progressively tailoring the atomic ratios of Ni/Fe, NiFe composites (Ni/Fe 1:1) were synthesized with more available active sites, enhanced stability, and excellent conductivity. As a result, the self-luminescent europium LMOFs displayed excellent performance characteristics in an ECL immunoassay with a minimum detectable limit of 0.126 pg mL −1 , using Cytokeratins21-1 (cyfra21-1) as the target detection model. The probability of false positive/false negative was reduced dramatically by using LMOFs as signal probes. This proposed strategy provides more possibilities for the application of lanthanide metals in analytical chemistry, especially in the detection of other disease markers.

Development of a novel label-free all-fiber optofluidic biosensor based on Fresnel reflection and its applications

“…Optical biosensors have widely been applied for the clinical diagnostics, environmental monitoring, and food detection because of their significant advantages including smaller size, high sensitivity, strong anti-interference ability, easy-to-use, and easier integration [ [1] , [2] , [3] ]. Among them, label-free optical biosensors have attracted greater interests because the biomolecules can be detected close to their natural morphology without being changed by fluorescence or other markers in the binding process [ 4 , 5 ]. This is especially useful for protein targets due to the labels may compromise their function.…”

“…Several factors are responsive for this. First, the end-surface of their transducers produced by single-mode fiber (SMF) is so small that the light-coupling efficiency and light-matter interaction is very low [ 4 ], thus resulting in a low detection of limit (LOD). Second, to eliminate the influence of light source power fluctuations, the aforementioned systems employed two fiber probes, a complex fiber coupler structure, and two photodetectors to detect the Fresnel reflection light signals of the sample and reference channels, respectively [ 14 , 16 ].…”

Wireless Electrochemical Visualization of Intracellular Antigens in Single Cells

“…Alternatively, as a near-zero background optical technique, electrochemiluminescence (ECL) is widely used for the sensitive and quantitative detection of various antigens in serum and cells. [8][9][10][11][12] In this process, the luminophore (e.g.…”

Co‐Quenching Effect between Lanthanum Metal–Organic Frameworks Luminophore and Crystal Violet for Enhanced Electrochemiluminescence Gene Detection

“…Recently, lanthanide MOFs have attracted our attention. [ 21–23 ] The special configurational transitions inside the 4f shell and the shield effect from 5s 2 and 5p 6 shells of lanthanide cations can cause long lifetime excited states and the inherent persistent luminescence property. [ 24,25 ] Likewise, aromatic polycarboxylate ligands are also a good choice for preparing MOFs‐based luminophore, which can not only serve as a chromophore in the coordinated frameworks, but also functionalize the surface of MOFs with abundant carboxyl groups for post‐modification application.…”