Rare Self-Luminous Mixed-Valence Eu-MOF with a Self-Enhanced Characteristic as a Near-Infrared Fluorescent ECL Probe for Nondestructive Immunodetection

Abstract

Steady and efficient sensitized emission of Eu 2+ to Eu 3+ can be achieved through a rare mixed-valence Eu-MOF (L 4 Eu III 2 Eu II ). Compared with the sensitization of other substances, the similar ion radius and configuration of the extranuclear electron between Eu 2+ and Eu 3+ make sensitization easier and more efficient. The sensitization of Eu 2+ to Eu 3+ is of great assistance for the selfenhanced luminescence of L 4 Eu III 2 Eu II , the longer luminous time, and the more stable electrochemiluminescence (ECL) signal. Simultaneously, L 4 Eu III 2 Eu II possesses near-infrared (NIR) fluorescence of around 900 nm and a mighty selfluminous characteristic, which render it useful as a NIR fluorescent probe and as a luminophore to establish a NIR ECL biosensor. This NIR biosensor can greatly reduce the damage to the detected samples and even achieve a nondestructive test and improve the detection sensitivity by virtue of strong susceptibility and environmental suitability of NIR. In addition, the CeO 2 @Co 3 O 4 triple-shelled microspheres further enhanced the ECL intensity due to two redox pairs of Ce 3+ / Ce 4+ and Co 2+ /Co 3+ . The NIR ECL biosensor based on these strategies owns an ultrasensitive detection ability of CYFRA 21-1 with a low limit of detection of 1.70 fg/mL and also provides a novel idea for the construction of a highly effective nondestructive immunodetection biosensor.

Pyrenecarboxaldehyde encapsulated porous TiO2 nanoreactors for monitoring cellular GSH levels

“…[8][9][10] For example, Wu's group reported a sandwich-type ECL immune-biosensor using CeO 2 @Co 3 O 4 triple-shell microspheres as co-reaction accelerators to increase the ECL signal of Eu-MOF with S 2 O 8 2− as the coreactant. 11 Nevertheless, the SO 4…”

“…8–10 For example, Wu's group reported a sandwich-type ECL immune-biosensor using CeO 2 @Co 3 O 4 triple-shell microspheres as co-reaction accelerators to increase the ECL signal of Eu-MOF with S 2 O 8 2− as the coreactant. 11 Nevertheless, the SO 4 ˙ − intermediates produced by CeO 2 @Co 3 O 4 need to diffuse to the Eu-MOF for ECL emission, this ternary ECLsystem had low utilization rates due to the short lifetime of SO 4 ˙ − . Thus, it is meaningful to improve the utilization rates of the intermediates.…”

Copper-Doped Terbium Luminescent Metal Organic Framework as an Emitter and a Co-reaction Promoter for Amplified Electrochemiluminescence Immunoassay

“…However, the application of these ECL nanocomposites, particularly Ru­(bpy) 3 2+ - or luminol-loaded MOFs, is greatly limited due to the leakage of small luminescence components, which influences seriously the stability of ECL emission and the accuracy of analysis. Therefore, the self-ECL properties of nanomaterials have attracted considerable attention. − Among these self-ECL nanomaterials, lanthanide MOFs hold great application prospects due to their long decay lifetime (∼ms) and high luminescence efficiency. − By introducing appropriate organic ligands, these ECL behaviors can be conveniently tuned by the antenna effect or the intramolecular energy transfer, while the low quantum yield of lanthanide elements due to the parity-forbidden f–f transitions can also be circumvented . However, most ECL studies on lanthanide MOFs mainly focus on europium-based MOFs (Eu-MOFs), − and the investigation of terbium-based MOFs (Tb-MOFs) is still in its infancy as the luminescence performance of Tb 3+ is inferior to that of Eu 3+ .…”

“…Therefore, the self-ECL properties of nanomaterials have attracted considerable attention. − Among these self-ECL nanomaterials, lanthanide MOFs hold great application prospects due to their long decay lifetime (∼ms) and high luminescence efficiency. − By introducing appropriate organic ligands, these ECL behaviors can be conveniently tuned by the antenna effect or the intramolecular energy transfer, while the low quantum yield of lanthanide elements due to the parity-forbidden f–f transitions can also be circumvented . However, most ECL studies on lanthanide MOFs mainly focus on europium-based MOFs (Eu-MOFs), − and the investigation of terbium-based MOFs (Tb-MOFs) is still in its infancy as the luminescence performance of Tb 3+ is inferior to that of Eu 3+ . Hence, exploration of effective and convenient ECL signal amplification strategies is highly desired for the application of Tb-MOFs in ECL bioassay.…”

Peptide-Based Electrochemiluminescence Biosensors Using Silver Nanoclusters as Signal Probes and Pd-Cu2O Hybrid Nanoconcaves as Coreactant Promoters for Immunoassays

“…However, the low luminescence intensity of metal NCs restricts their application, so it is necessary to develop a highly efficient way to improve their luminescence efficiency. At present, in addition to the traditional means of acting on luminescent materials to increase ECL emission, for example, developing high-performance luminophore and using the energy resonance transfer strategy, we can also focus on the catalysis of coreactants by developing high-efficiency coreaction promoters. − Therefore, a ternary reaction system including a luminophore, coreactant, and coreaction promoter was developed. The proposed ternary reaction system avoids the restrictions on the high-concentration luminophore and coreactant, which is conducive to maintaining the activity of biomarkers .…”