Electrochemiluminescence resonance energy transfer of MnCO3 for ultrasensitive amyloid-β protein detection

Signal-on electrochemiluminescence resonance energy transfer biosensor for miRNA-543 based on CRISPR/Cas13a and magnetic separation

In this study, an electrochemiluminescence resonance energy transfer (ECL-RET) biosensor with high sensitivity and strong resistance to interference was constructed based on the CRISPR/Cas13a system and magnetic separation for ovarian cancer biomarker miR-543 detection. Mesoporous silica nanoparticles embedded with Ru(bpy)32+ (Ru@SiO2) have high electrochemiluminescence (ECL) response was chosen as energy donor. Single-stranded DNA S1 containing "rUrU" motif was immobilized on AuNRs (AuNRs-S1), which hybridized with single-stranded DNA S2 modified SAMBs (SAMBs-S2) to form AuNRs-S1/S2-SAMBs complex, this has been used as energy acceptor. In the absence of the target, Cas13a remained inactive, preventing the cleavage of S1, thereby maintaining the association of AuNRs with SAMBs. Then they were added in Ru@SiO2 solution after magnetic separation. The electrostatic adsorption between the negatively charged AuNRs and the positively charged Ru@SiO2 cause the occurrence of ECL-RET and low ECL signal had been detected. When the target was added, Cas13a was activated and resulted in the non-specifically cleaving of S1, so AuNRs detached from SAMBs. After magnetic separation, fewer AuNRs participated in ECL-RET, leading to an enhanced ECL signal detected. The change in ECL intensity (ΔECL) exhibited a linear correlation with the logarithm of miR-543 concentration within the range of 10 fM to 10 nM, with a detection limit of 6.91 fM. The biosensor had been applied to detect miR-543 in clinical samples with high accuracy.

2D Zn-based metal-organic framework as an efficient electrochemiluminescence emitter: A novel inner filter effect-based ECL biosensor for trace detection of bisphenol A

The potential hazards of bisphenol A (BPA) to the environment have become a global concern. Herein, 2D Zn-based metal-organic framework nanosheet (2D Zn-MOF) and MnCO3 nanocomposite (Zn-MOF-MnCO3), an efficient electrochemiluminescence (ECL) probe was first synthesized and constructed for trace detection of BPA. Owing to the elimination of the aggregation-induced quenching (ACQ) effect of polycyclic aromatic hydrocarbons (PAHs), the leaf-like Zn-MOF exhibited a satisfactory ECL signal. The MnCO3, which has excellent biocompatibility, showed excellent ECL efficiency in the presence of K2S2O8. With the covalent binding of Zn-MOF and MnCO3, we demonstrated that the ECL intensity and stability of Zn-MOF-MnCO3 improved significantly. In addition, the inner filter effect (IFE) of Fe3O4-NH2 NPs toward Zn-MOF-MnCO3 had been confirmed to be the ECL quenching mechanism. Based on above strategies, the proposed ECL-IFE biosensor exhibited a trace detection ability of BPA in a wide linear range (10 fM ∼ 10 μM) with a low detection limit (4.2 fM). Further in-depth study confirmed the excellent repeatability, selectivity, and stability of sensors, which provided a fresh sensing platform for trace detection of BPA in the environment.

An electrochemiluminescence sensor based on Ag NPs amplifying PDDA-modified TbPO4:Ce NWs signal for sensitive detection of lincomycin

The residue of lincomycin in water will not only aggravate the drug resistance of bacteria but also cause damage to the human body through biological accumulation. In this work, an electrochemiluminescence (ECL) aptasensor for the detection of lincomycin was constructed based on polydimethyldiallylammonium chloride (PDDA) functionalized Ce-doped TbPO4 nanowires (PDDA-TbPO4:Ce NWs) and silver nanoparticles (Ag NPs). TbPO4:Ce NWs were used as the luminophore, and PDDA was used to functionalize the luminophore to make the surface of the luminophore positively charged. The negatively charged silver nanoparticles were combined with PDDA-TbPO4:Ce NWs by electrostatic interaction. Ag NPs accelerated the electron transfer rate and promoted the ECL efficiency, which finally increased the ECL intensity of TbPO4:Ce NWs by about 4 times. Under the optimal conditions, the detection limit of the ECL sensor was as low as 4.37 × 10-16 M, and the linear range was 1 × 10 - 15 M to 1 × 10 - 5 M, with good selectivity, stability, and repeatability. The sensor can be applied to the detection of lincomycin in water, and the recovery rate is 97.7-103.4 %, which has broad application prospects.

Sensitive electrochemiluminescence immunosensor based on a novel luminescent europium metal-organic framework and antenna effect for detecting pro-gastrin-releasing peptide

Sensitive detection of pro-gastrin-releasing peptide (Pro-GRP) is crucial because it is a highly sensitive and specific tumor marker for small cell lung cancer. Herein, we synthesized an efficient luminescent europium metal-organic framework and developed a sandwich ECL immunosensor for the sensitive detection of Pro-GRP, which used Eu3+ as the central ion and 2,4,6-tri (4-carboxyphenyl)-1,3,5-triazine (H3TATB) as the organic ligand. H3TATB acted as a strong absorbing reagent and transferred its energy to Eu3+ via the antenna effect to enhance the ECL response signal of Eu3+. As per calculations, the ECL efficiency of Eu-TATB, which was a promising ECL luminophore, was up to 130 %. The Cu2O cube worked as a substrate to assist the electron transfer and was used as a co-reaction accelerator to catalyze S2O82- to produce more SO4•- and then enhance the ECL intensity of Eu-TATB. Under optimal experimental conditions, the ECL immunosensor had a linear range of 5 fg mL-1-50 ng mL-1 for detecting Pro-GRP with a detection limit of 1.6 fg mL-1; moreover, it demonstrated excellent stability and specificity and has been successfully applied for detecting Pro-GRP in the human serum.

Advances in targeted tracking and detection of soluble amyloid-β aggregates as a biomarker of Alzheimer's disease

Misfolding and aggregation of amyloid-β (Aβ) peptides are key hallmarks of Alzheimer's disease (AD). With accumulating evidence suggesting that different Aβ species have varied neurotoxicity and implications in AD development, the discovery of affinity ligands and analytical approaches to selective distinguish, detect, and monitor Aβ becomes an active research area. Remarkable advances have been achieved, which not only promote our understanding of the biophysical chemistry of the protein aggregation during neurodegeneration, but also provide promising tools for early detection of the disease. In view of this, we summarize the recent progress in selective and sensitive approaches for tracking and detection of Aβ species. Specific attentions are given to soluble Aβ oligomers, due to their crucial roles in AD development and occurrence at early stages. The design principle, performance of targeting units, and their cooperative effects with signal reporters for Aβ analysis are discussed. The applications of the novel targeting probes and sensing systems for dynamic monitoring oligomerization, measuring Aβ in biosamples and in vivo imaging in brain are summarized. Finally, the perspective and challenges are discussed regarding the future development of Aβ-targeting analytical tools to explore the unknown field to contribute to the early diagnosis and treatment of AD.

Electrochemiluminescence resonance energy transfer between a Ru-ZnMOF self-enhanced luminophore and a double quencher ZnONF@PDA to detect NSE

The construction of advanced systems capable of accurately detecting neuron-specific enolase (NSE) is essential for rapidly diagnosing small-cell lung cancer. In this study, an electrochemiluminescence (ECL) resonance energy transfer immunosensor was proposed for the ultra-sensitive detection of NSE. The co-reactants C2O42- and Ru(bpy)32+ were integrated to form a self-enhanced ECL luminophore (Ru-ZnMOF) as the ECL donor. The abundant carboxyl functional groups of Ru-ZnMOF supported antibody 1 via an amidation reaction. Polydopamine-modified zinc dioxide nanoflowers, as ECL acceptors, inhibited Ru-ZnMOF ECL signaling. The linear range of NSE was 10 fg mL-1 to 100 ng mL-1 with a detection limit of 3.3 fg mL-1 (S/N = 3), which is suitably low for determining NSE in real samples.

SAM-Support-Based Electrochemical Sensor for Aβ Biomarker Detection of Alzheimer's Disease

Alzheimer's disease has taken the spotlight as a neurodegenerative disease which has caused crucial issues to both society and the economy. Specifically, aging populations in developed countries face an increasingly serious problem due to the increasing budget for patient care and an inadequate labor force, and therefore a solution is urgently needed. Recently, diverse techniques for the detection of Alzheimer's biomarkers have been researched and developed to support early diagnosis and treatment. Among them, electrochemical biosensors and electrode modification proved their effectiveness in the detection of the Aβ biomarker at appropriately low concentrations for practice and point-of-care application. This review discusses the production and detection ability of amyloid beta, an Alzheimer's biomarker, by electrochemical biosensors with SAM support for antibody conjugation. In addition, future perspectives on SAM for the improvement of electrochemical biosensors are also proposed and discussed.

Au@NiFeMOFs as the signal quencher of Au@g-C3N4NSs composite for sensitive "on-off" electrochemiluminescence immunosensing of beta-2-microglobulin

In this study, an electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was constructed to detect beta-2-microglobulin (B2M). As a donor-acceptor pair, a carbon nitride nanosheet modified with gold nanoparticles (Au@g-C₃N₄NSs) and a nickel- and iron-based organic framework modified with gold nanoparticles (Au@NiFeMOFs) were prepared. The sandwich immunosensor was successfully constructed so that ECL-RET occurred between Au@NiFeMOFs and Au@g-C₃N₄NSs. The ECL intensity of the immunosensor decreased with the increase the B2M concentration due to the low conductivity of B2M. The linear range of the ECL-RET immunosensor was from 10 fg/mL to 10 ng/mL, and the limit of detection was 2.3 fg/mL (S/N = 3). The developed immunosensor had high sensitivity, high specificity, and excellent stability. It could realize the sensitivity test of B2M and provide a novel idea for the detection of biomarkers.

Aggregation-Induced Electrochemiluminescence Based on a Zinc-Based Metal-Organic Framework and a Double Quencher Au@UiO-66-NH2 for the Sensitive Detection of Amyloid β 42 via Resonance Energy Transfer

A novel sandwich electrochemiluminescence (ECL) biosensor based on aggregation-induced electrochemiluminescence resonance energy transfer (AIECL-RET) was designed for the sensitive detection of amyloid β42 (Aβ42). The synthesized silver nanoparticle-functionalized zinc metal-organic framework (Ag@ZnPTC) and gold nanoparticle-functionalized zirconium organic framework (Au@UiO-66-NH₂) were used as the ECL donor and acceptor, respectively. AgNPs were generated in situ on the surface of ZnPTC, which further improved the ECL intensity and the loading of antibody 1 (Ab1). Under the optimized experimental conditions, the linear detection range of Aβ42 concentration was 10 fg/mL to 100 ng/mL, and the detection limit was 2.4 fg/mL (S/N = 3). The recoveries of Aβ42 were 99.5-104%. The method has good stability, repeatability, and specificity. Ag@ZnPTC/Au@UiO-66-NH₂ provides an assay for the sensitive detection of disease biomarkers.