MnOx MFs as a coreaction accelerator for the construction of a novel ternary electrochemiluminescence system: ultrasensitive detection of microRNA

Recent Advances in Electrochemiluminescence Biosensors for MicroRNA Detection

Electrochemiluminescence (ECL) as an analytical technology with a perfect combination of electrochemistry and spectroscopy has received considerable attention in bioanalysis due to its high sensitivity and broad dynamic range. Given the selectivity of bio-recognition elements and the high sensitivity of the ECL analysis technique, ECL biosensors are powerful platforms for the sensitive detection of biomarkers, achieving the accurate prognosis and diagnosis of diseases. MicroRNAs (miRNAs) are crucial biomarkers involved in a variety of physiological and pathological processes, whose aberrant expression is often related to serious diseases, especially cancers. ECL biosensors can fulfill the highly sensitive and selective requirements for accurate miRNA detection, prompting this review. The ECL mechanisms are initially introduced and subsequently categorize the ECL biosensors for miRNA detection in terms of the quenching agents. Furthermore, the work highlights the signal amplification strategies for enhancing ECL signal to improve the sensitivity of miRNA detection and finally concludes by looking at the challenges and opportunities in ECL biosensors for miRNA detection.

Simultaneous Detection of Ovarian Cancer-Concerned HE4 and CA125 Markers Based on Cu Single-Atom-Triggered CdS QDs and Eu MOF@Isoluminol ECL

Simultaneous detection of different disease markers is significant for clinical diagnosis. In this work, a dual-signal electrochemiluminescence (ECL) immunosensor was constructed for the simultaneous detection of carbohydrate antigen 125 (CA125) and human epithelial protein 4 (HE4) markers of ovarian cancer. The results showed that the Eu metal-organic framework-loaded isoluminol-Au nanoparticles (Eu MOF@Isolu-Au NPs) could generate a strong anodic ECL signal through synergistic interaction; as cathodic luminophore, the composite of carboxyl-functionalized CdS quantum dots and N-doped porous carbon-anchored Cu single-atom catalyst could catalyze H₂O₂ co-reactant to produce a large amount of ^•OH and O₂^•-, making the anodic and cathodic ECL signals significantly increase and become stable. Based on the enhancement strategy, a sandwich immunosensor was constructed for the simultaneous detection of ovarian cancer-associated CA125 and HE4 markers by combining antigen-antibody specific recognition and magnetic separation technique. The resulting ECL immunosensor displayed high sensitivity, a wide linear response range of 0.005∼500 ng mL^-1, and low detection limits of 0.37 and 1.58 pg mL^-1 for CA125 and HE4, respectively. Furthermore, it had excellent selectivity, stability, and practicability in the detection of real serum samples. This work establishes a framework for in-depth design and application of single-atom catalysis in ECL sensing.

Electrochemiluminescence nanoemitters for immunoassay of protein biomarkers

The family of electrochemiluminescent luminophores has witnessed quick development since the electrochemiluminescence (ECL) phenomenon of silicon nanoparticles was first reported in 2002. Moreover, these developed ECL nanoemitters have extensively been applied in sensitive detection of protein biomarker by combining with immunological recognition. This review firstly summarized the origin and development of various ECL nanoemitters including inorganic and organic nanomaterials, with an emphasis on metal-organic frameworks (MOFs)-based ECL nanoemitters. Several effective strategies to amplify the ECL response of nanoemitters and improve the sensitivity of immunosensing were discussed. The application of ECL nanoemitters in immunoassay of protein biomarkers for diagnosis of cancers and other diseases, especially lung cancer and heart diseases, was comprehensively presented. The recent development of ECL imaging with the nanoemitters as ECL tags for detection of multiplex protein biomarkers on single cell membrane also attracted attention. Finally, the future opportunities and challenges in the ECL biosensing field were highlighted.

Plasmon-Boosted Fe, Co Dual Single-Atom Catalysts for Ultrasensitive Luminol-Dissolved O2 Electrochemiluminescence Detection of Prostate-Specific Antigen

Improving the sensitivity of electrochemiluminescence (ECL) systems is highly desired for in vitro ECL diagnosis and bio-detections due to the often-low content of biomarkers in diseases. And dissolved O₂ (DO) as a co-reactant is considered superior to H₂O₂ in the most commonly used luminol ECL systems due to better stability and low biotoxicity, but it still suffers from low ECL performance due to the low reactivity of DO. In this study, an efficient luminol-DO ECL system was developed through the complexing of Fe, Co dual single-atom catalysts (D-SACs) supported by N-doped graphene with the luminol-capped Ag nanoparticles (AgNPs). Benefiting from the electronic interaction between Fe and Co metal sites in the relevant D-SACs and plasmon enhancement of AgNPs, the performance of the corresponding ECL system could be significantly boosted up to ≈677-fold under optimal testing conditions, comparable to the classic luminol-O₂ system. Furthermore, the developed luminol-DO ECL system was successfully applied for the stable ultrasensitive detection of prostate-specific antigen (PSA) in a wide linear range of 1 fg/mL to 1 μg/mL, with a low limit of detection (0.98 fg/mL).

Dual-Mode Immunosensor for Electrochemiluminescence Resonance Energy Transfer and Electrochemical Detection of Rabies Virus Glycoprotein Based on Ru(bpy)32+-Loaded Dendritic Mesoporous Silica Nanoparticles

Rabies is a serious zoonotic disease in almost all warm-blooded animals and causes fatal encephalitis. The detection of rabies virus (RABV) is critical and remains a significant challenge. Herein, an electrochemiluminescence resonance energy transfer (ECL-RET) and electrochemical (EC) dual-mode immunosensor was developed for highly sensitive detection of RABV glycoprotein. Dendritic mesoporous silica nanoparticles (DMSNs) were employed to load Ru(bpy)₃²⁺ and to obtain ECL probes (Ru@DMSNs). Ru@DMSNs were decorated on the electrode surface, followed by the modification of the RABV antibody (Ab₁). RABV was specifically recognized and captured by Ab₁, causing the decline of the ECL signal due to the obstruction of electron transfer. Additionally, manganese oxide nanoparticles (MnO_x) modified with Ab₂ can further quench the ECL signal of Ru@DMSNs via the RET between Ru@DMSNs and MnO_x. Meanwhile, MnO_x can catalyze the oxidation of o-phenylenediamine (o-PD), generating a significant differential pulse voltammetry (DPV) signal as a second signal to monitor RABV glycoprotein concentration. Consequently, an immunosensor was developed to achieve dual-signal detection of RABV and improve reliability. Under the optimal conditions, detection ranges of 0.10 pg·mL^-1 to 10 ng·mL^-1 for ECL (with an 88 fg·mL^-1 detection limit) and 1 pg·mL^-1 to 2 ng·mL^-1 for EC (with a 0.1 pg·mL^-1 detection limit) were obtained for RABV detection. The reliability of this immunoassay was validated by eight brain tissue samples. The results were found to be compatible with the results of the real-time reverse transcription-polymerase chain reaction (RT-PCR) assay, indicating the potential applicability of this method for RABV diagnosis.