Oxygen Vacancy-Enhanced Electrochemiluminescence Sensing Strategy Using Luminol Thermally Encapsulated in Apoferritin as a Transducer for Biomarker Immunoassay

Co3O4/NiCo2O4 heterojunction as oxygen evolution reaction catalyst for efficient luminol anode electrochemiluminescence

Luminol has garnered significant attention from analysts as one of the most effective and commonly used electrochemiluminescence (ECL) reagents. However, the efficient luminescence of luminol anode is limited by the excitation of various reactive oxygen species (ROS). Typically, ROS are generated through co-reactive reagents and dissolved oxygen. Unfortunately, the former suffers from two drawbacks, namely biotoxicity and instability, while the latter cannot offer sufficient oxygen due to its limited solubility in aqueous solutions. Consequently, a low decomposition rate is usually obtained, leading to insufficient ROS. Therefore, there is an urgent need to develop efficient luminol anode systems. This study focuses on the use of zeolitic imidazolate framework-67 (ZIF-67) as a template, employing a controlled chemical etching method to create a ZIF-67/Ni-Co-layered double hydroxide (LDH). The intermediate composite is then annealed in air, resulting in the formation of a Co3O4/NiCo2O4 double-shelled nanobox (DSNB) heterostructure. Due to its structural advantages, the DSNB exhibits excellent electrocatalytic performance in the oxygen evolution reaction (OER). Furthermore, it was found that both the intermediates and products of OER can directly participate in the luminol chemiluminescence process, ultimately resulting in a 700-fold increase in the electrochemiluminescence (ECL) signal compared to an equal molar concentration of luminol solution. This work not only establishes the OER-mediated ECL system but also deepens the understanding of the relationship between ROS and luminol, providing a new pathway to study the luminol anodic ECL luminescence system.

Electroless Deposition of Palladium Nanoparticles on Graphdiyne Boosts Electrochemiluminescence

Modulating the electronic structure of metal nanoparticles via metal-support interaction has attracted intense interest in the field of catalytic science. However, the roles of supporting substrates in regulating the catalytic properties of electrochemiluminescence (ECL) remain elusive. Here, we find that the use of graphdiyne (GDY) as the substrate for electroless deposition of Pd nanoparticles (Pd/GDY) produces the most pronounced anodic signal enhancement in luminol-dissolved oxygen (O2) ECL system as co-reactant accelerator over other carbon-based Pd composite nanomaterials. Pd/GDY exhibits electrocatalytic activity for the reduction of O2 through a four-electron pathway at approximately -0.059 V (vs Ag/AgCl) in neutral solution forming reactive oxygen species (ROS) as intermediates. The study shows that the interaction of Pd and GDY increases the amount and stability of ROS on the Pd/GDY electrode surface and promotes the reaction of ROS and luminol anion radical to generate excited luminol, which significantly boosts the luminol anodic ECL emission. Based on quenching of luminol ECL through the consumption of ROS by antioxidants, we develop a platform for the detection of intracellular antioxidants. This study provides an avenue for the development of efficient luminol ECL systems in neutral media and expands the biological application of ECL systems.

A review of nanomaterials for biosensing applications

A biosensor is a device that reacts with the analyte to be analyzed, detects its concentration, and generates readable information, which plays an important role in medical diagnosis, detection of physiological indicators, and disease prevention. Nanomaterials have received increasing attention in the fabrication and improvement of biosensors due to their unique physicochemical and optical properties. In this paper, the properties of nanomaterials such as the size effect, optical and electrical properties, and their advantages in the field of biosensing are briefly summarized, and the application of nanomaterials can effectively improve the sensitivity and reduce the detection limit of biosensors. The advantages of commonly used nanomaterials such as gold nanoparticles (AuNPs), carbon nanotubes (CNTs), quantum dots (QDs), graphene, and magnetic nanobeads for biosensor applications are also reviewed. Besides, the two main types of biosensors using nanomaterials involved in their construction and their working principles are described, and the toxicity and biocompatibility of nanomaterials and the future direction of nanomaterial biosensors are discussed.

Atomically Fe-anchored MOF-on-MOF nanozyme with differential signal amplification for ultrasensitive cathodic electrochemiluminescence immunoassay

The successful application of electrochemiluminescence (ECL) in immunoassays for clinical diagnosis requires stable electrodes and high-efficient ECL signal amplification strategies. Herein, the authors discovered a new class of atomically dispersed peroxidase-like nanozymes with multiple active sites (CoNi-MOF@PCN-224/Fe), which significantly improved the catalytic performance and uncovered the underlying mechanism. Experimental studies and theoretical calculation results revealed that the nanozyme introduced a Fenton-like reaction into the catalytic system and the crucial synergistic effects of definite active moieties endow CoNi-MOF@PCN-224/Fe strong electron-withdrawing effect and low thermodynamic activation energy toward H2O2. Benefiting from the high peroxidase-like activity of the hybrid system, the resultant ECL electrode exhibited superior catalytic activity in the luminol-H2O2 system and resulted in an ≈17-fold increase in the ECL intensity. In addition, plasmonic Ag/Au core-satellite nanocubes (Ag/AuNCs) were designed as high-efficient co-reactant quenchers to improve the performance of the ECL immunoassay. On the basis of the differential signal amplification strategy (DSAS) proposed, the immunoassay displayed superior detection ability, with a low limit of detection (LOD) of 0.13 pg mL-1 for prostate-specific antigen (PSA). The designed atomically anchored MOF-on-MOF nanozyme and DSAS strategy provides more possibilities for the ultrasensitive detection of disease markers in clinical diagnosis.

A Carbonate-Involved Amplification Strategy for Cathodic Electrochemiluminescence of Luminol Triggered by the Catalase-like CoO Nanorods

The lumiol-O₂ electrochemiluminescence (ECL) system constantly emits bright light at positive potential. Notably, compared with the anodic ECL signal of the luminol-O₂ system, the great virtues of cathodic ECL are that it is simple and causes minor damage to biological samples. Unfortunately, little emphasis has been paid to cathodic ECL, owing to the low reaction efficacy between luminol and reactive oxygen species. The state-of-the-art work mainly focuses on improving the catalytic activity of the oxygen reduction reaction, which remains a significant challenge. In this work, a synergistic signal amplification pathway is established for luminol cathodic ECL. The synergistic effect is based on the decomposition of H₂O₂ by catalase-like (CAT-like) CoO nanorods (CoO NRs) and regeneration of H₂O₂ by a carbonate/bicarbonate buffer. Compared with Fe₂O₃ nanorod (Fe₂O₃ NR)- and NiO microsphere-modified glassy carbon electrodes (GCEs), the ECL intensity of the luminol-O₂ system is nearly 50 times stronger when the potential ranged from 0 to -0.4 V on the CoO NR-modified GCE in a carbonate buffer solution. The CAT-like CoO NRs decompose the electroreduction product H₂O₂ into OH^· and O₂^·-, which further oxidize HCO₃^- and CO₃^2- to HCO₃^· and CO₃^·-. These radicals very effectively interact with luminol to form the luminol radical. More importantly, H₂O₂ can be regenerated when HCO₃^· dimerizes to produce (CO₂)₂*, which provides a cyclic amplification of the cathodic ECL signal during the dimerization of HCO₃^·. This work inspires developing a new avenue to improve cathodic ECL and deeply understand the mechanism of a luminol cathodic ECL reaction.

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.

Enhanced Electrochemiluminescence of Graphitic Carbon Nitride by Adjustment of Carbon Vacancy for Supersensitive Detection of MicroRNA

Herein, a supersensitive biosensor was constructed by using graphitic carbon nitride with a carbon vacancy (V_C-g-C₃N₄) as an efficient electrochemiluminescence (ECL) emitter for detection of microRNA-21 (miRNA-21). Impressively, V_C-g-C₃N₄ could be prepared by formaldehyde (HCHO)-assisted urea ploycondensation, and the concentration of the carbon vacancy could be controlled by adjusting the dosage of HCHO to improve the ECL performance, in which the carbon vacancy could improve the charge carrier transfer to enhance the conductivity and it also could be used as an electron trap to prevent electrode passivation and facilitate the adsorption of coreactant S₂O₈^2- to accelerate its reduction. Compared with original g-C₃N₄, the introduction of carbon vacancies resulted in a significant enhancement of the ECL efficiency of V_C-g-C₃N₄. With the aid of improved cascade strand displacement amplification (IC-SDA), the ECL biosensor realized sensitive detection of miRNA-21 with a low detection limit of 3.34 aM. This successful strategy promoted the development of g-C₃N₄ in the ECL field to construct the sensitive biosensor for molecular and disease diagnoses.

Catalytic Decomposition of the Hole-Derived H2O2 by AgBiS2@Ag Nanozyme to Enhance the Photocurrent of Z-Scheme BiVO4/ZnIn2S4 Photoelectrode in Microfluidic Immunosensing Platform

A novel microfluidic photoelectrochemical (PEC) analytical device based on AgBiS₂@Ag nanozyme-mediated signal amplification was developed for ultrasensitive detection of cytokeratin 19 fragment 21-1 (CYFRA 21-1). First, a brand new Z-scheme BiVO₄/ZnIn₂S₄ (BZIS) photoactive material was utilized as a sensing matrix to supply a stable photocurrent. Under anodic bias, the photoexcited holes in BiVO₄ could oxidize water to produce hydrogen peroxide (H₂O₂), which markedly enhanced the separation efficiency of the electron-hole pairs. Besides, the Z-scheme heterojunction formed between BiVO₄ and ZnIn₂S₄ further accelerated the transport of the electron. Second, for improving the sensitivity of the PEC sensor, a new strategy of catalytic dissociation of the hole-derived H₂O₂ by AgBiS₂@Ag nanozyme was proposed to amplify the PEC signal. AgBiS₂@Ag composites, possessing an excellent peroxidase-mimicking feature, could efficiently catalyze the H₂O₂ to produce hydroxyl radicals (^•OH) and lead to the significant enhancement of the photocurrent. Third, automatic sample injection and detection were successfully realized by integrating the photoelectrode into microfluidic chips. Based on this advanced sensing strategy, the designed microfluidic PEC sensor displayed a wide linear range (0.1 pg/mL - 100 ng/mL) and a low detection limit of 35 fg/mL (S/N = 3), which could be efficiently applied to the ultrasensitive determination of CYFRA 21-1 in a human serum sample.

Single-Atom Iron Enables Strong Low-Triggering-Potential Luminol Cathodic Electrochemiluminescence

The conventional cathodic electrochemiluminescence (ECL) always requires a more negative potential to trigger strong emission, which inevitably damages the bioactivity of targets and decreases the sensitivity and specificity. In this work, iron single-atom catalysts (Fe-N-C SACs) were employed as an efficient co-reaction accelerator for the first time to achieve the impressively cathodic emission of a luminol-H₂O₂ ECL system at an ultralow potential. Benefiting from the distinct electronic structure, Fe-N-C SACs exhibit remarkable properties for the activation of H₂O₂ to produce massive reactive oxygen species (ROS) under a negative scanning potential from 0 to -0.2 V. The ROS can oxidize the luminol anions into luminol anion radicals, avoiding the tedious electrochemical oxidation process of luminol. Then, the in situ-formed luminol anion radicals will directly react with ROS for the strong ECL emission. As a proof of concept, sensitive detection of the carcinoembryonic antigen was realized by glucose oxidase-mediated ECL immunoassay, shedding light on the superiority of SACs to construct efficient cathodic ECL systems with low triggering potential.

Self-powered photoelectrochemical biosensor with inherent potential for charge carriers drive

Self-powered photoelectrochemical (PEC) sensing platform without external voltage has provided a breakthrough in the development of biosensors, however, it is necessary to find suitable Fermi energy level difference between photoanode materials and photocathode materials as the driving force. Herein, the self-powered PEC sensor was developed to combine the advantages of both the photoanode (SnS₂/In₂S₃) and the photocathode (CuInS₂). The sufficient Fermi level differentiation between the photoanode with the photocathode not only resulted in an evident photocurrent response vis tuning the electron transfer but avoided redox reactions of extra electron donors/acceptors to enhance the accuracy of the sensor. The biological target was immobilized on the photocathode, which allowed the sensor to possess a good anti-interference capability for the detection of real samples. The proposed PEC sensor exhibits good sensitivity for the cytokeratin 19 fragment (CYFRA21-1) detection and a low limit of detection (LOD) of 6.57 fg mL^-1. Moreover, the as-purposed PEC system with good anti-interference capability and accuracy has implications for the detection of other biomarkers.

Rational Construction of a Ni/CoMoO4 Heterostructure with Strong Ni-O-Co Bonds for Improving Multifunctional Nanozyme Activity

Due to the lack of a general descriptor to predict the activity of nanomaterials, the current exploration of nanozymes mainly depended on trial-and-error strategies, which hindered the effective design of nanozymes. Here, with the help of a large number of Ni-O-Co bonds at the interface of heterostructures, a prediction descriptor was successfully determined to reveal the double enzyme-like activity mechanisms for Ni/CoMoO₄. Additionally, DFT calculations revealed that interface engineering could accelerate the catalytic kinetics of the enzyme-like activity. Ni-O-Co bonds were the main active sites for enzyme-like activity. Finally, the colorimetric signal and intelligent biosensor of Ni/CoMoO₄ based on deep learning were used to detect organophosphorus and ziram sensitively. Meanwhile, the in situ FTIR results uncovered the detection mechanism: the target molecules could block Ni-O-Co active sites at the heterostructure interface leading to the signal peak decreasing. This study not only provided a well design strategy for the further development of nanozymes or other advanced catalysts, but it also designed a multifunctional intelligent biosensor platform. Furthermore, it also provided preferable ideas regarding the catalytic mechanism and detection mechanism of heterostructure nanozymes.

Surface Bonding Enhanced Self-Co-Reactant Electrogenerated Chemiluminescence for Sensitive and Selective Detection of Thioglycolic Acid in Cosmetics

Thioglycolic acid (TGA) is an organic compound widely used in cosmetics that cause a variety of health problems when overexposed to it. So far many attempts have been made to develop methods for TGA detection, but most of them need sophisticated instrumentations and are a little bit complicated. Therefore, a simple, cheap and sensitive detection method of TGA is highly desired. Herein, we demonstrated for the first time an Au-S bonding amplified, highly sensitive electrochemiluminescence (ECL) sensing method for TGA detection using tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy) 3 2+ ) as a luminophore and TGA as a self-co-reactant, via an anodic reaction at the Au electrode surface. Due to different molecular coordination environments of the TGA at the electrode surface, the ECL signal intensity of the developed ECL system gives much higher ECL signal in borate buffer than phosphate buffer of the same pH. Under the optimized experimental conditions, the ECL intensity has a direct relationship with the concentration of TGA in the range of 0.03 μM to 300 μM and a limit of detection of 0.013 µM (3σ/ m ). The reported ECL system has further been applied for the detection of TGA in cosmetics with acceptable recoveries.

Versatile Luminol/Dissolved Oxygen/Fe@Fe2O3 Nanowire Ternary Electrochemiluminescence System Combined with Highly Efficient Strand Displacement Amplification for Ultrasensitive microRNA Detection

Herein, a versatile ECL biosensor was fabricated for ultrasensitive detection of microRNA-21 (miRNA-21) from cancer cells based on a novel H₂O₂-free electrochemiluminescence (ECL) system (luminol/dissolved oxygen/Fe@Fe₂O₃ nanowires). Compared with the previously reported coreaction accelerator that needed a negative potential to produce reactive oxygen species (ROS), these newly discovered Fe@Fe₂O₃ nanowires could generate ROS in the detection solution immediately without the application of voltage, which narrowed down the detection potential range to avoid side reactions, favoring their practical application in biological systems. Especially, the Fe@Fe₂O₃ nanowires could produce H^• for activating dissolved oxygen into ROS to improve the ECL intensity dramatically, which initiates a novel pathway to promote the generation of ROS for the ECL system. In addition, an original strand displacement amplification coupled with strand displacement reaction (SDA-SDR) was developed to improve the conversion efficiency of the target for sensitive detection of miRNA-21. By virtue of the SDR, a quadruple quenching effect was achieved through each output DNA strand of SDA; hence, the nucleic acid signal amplification efficiency was effectively enhanced. As expected, on account of the superb activation performance of Fe@Fe₂O₃ nanowires and the outstanding amplification efficiency of the SDR-SDA strategy, the fabricated ECL biosensor realized ultrasensitive detection of miRNA-21 with a detection limit down to 52.5 aM. The established ECL sensing platform ushered a new route for H₂O₂-free detection and a promising biomarker assay method for clinical diagnosis.

Novel Enhanced Lanthanide Electrochemiluminescence Luminophores: Ce3+-Doped TbPO4 Facile Synthesis and Detection for Mucin1

Despite the upsurging interest in electrochemiluminescence (ECL) of lanthanides, the research in this field is still in its infancy due to the low intensity. In this work, a series of Ce³⁺-doped terbium orthophosphates (TbPO₄:Ce) in different proportions have been synthesized through the co-precipitation method at room temperature. Meanwhile, through the investigation of morphologies and ECL properties of these TbPO₄:Ce, it is concluded that the ECL intensity reaches the maximum when the molar ratio of Tb/Ce is 9:1 and the material is nanorod-shaped. The ECL intensity of TbPO₄:Ce is significantly improved by doping with Ce³⁺ due to the dual sensitization strategy of the antenna effect from PO₄^3- to Tb³⁺ and the energy transfer from Ce³⁺ to Tb³⁺. Interestingly, doping with Ce³⁺ can not only adjust morphology of TbPO₄:Ce but also improve the ECL intensity. In addition, to verify the application of TbPO₄:Ce, two single mucin1 (MUC1) aptamers are linked together to form a dual MUC1 aptamer chain. Then, a simple and sensitive ECL biosensor is constructed for the detection of MUC1, which can recognize the double amount of MUC1 and quench the ECL signal. As expected, the proposed biosensor shows good stability and acceptable selectivity and achieves sensitive detection of MUC1 with a dynamic range from 1 fg·mL^-1 to 10 ng·mL^-1 and a limit of detection of 0.5 fg·mL^-1. This work may pave a new avenue for the study of direct ECL emission of lanthanides and prove to be ideal for the research of new ECL luminophores in electrochemical analysis.

Nitrogen-Doped Chiral CuO/CoO Nanofibers: An Enhanced Electrochemiluminescence Sensing Strategy for Detection of 3,4-Dihydroxy-Phenylalanine Enantiomers

l-3,4-Dihydroxy-phenylalanine (l-DOPA) is the most effective drug for the treatment of Parkinson's disease, which plays a very important role in clinical and neurochemistry. However, how to achieve high-sensitivity recognition of l-DOPA still faces challenges. Here, a facile strategy is presented to construct nitrogen-doped chiral CuO/CoO nanofibers (N-CuO/CoO NFs) with nanozyme activity and electrochemiluminescence property, in which CuO/CoO NFs are used as the catalytic activity center and chiral cysteine (Cys) is used as the inducer of chiral recognition, for enantioselective catalysis and sensitive recognition of DOPA enantiomers. Notably, N doping not only enhances the enzyme-mimic activity of CuO/CoO NFs but also amplifies their electrochemiluminescence (ECL) signals in the presence of luminol. More importantly, in the presence of DOPA enantiomers, the d-cysteine (d-Cys)-modified N-CuO/CoO NFs exhibit different ECL performances; thus, d-Cys@N-CuO/CoO NFs could selectively distinguish and sensitively detect l-DOPA through ECL signals, and the detection limit is 0.29 nM for l-DOPA. In addition, it also showed good sensing performance for the determination of l-DOPA in fetal bovine serum. This is the first report on the detection of DOPA enantiomers based on an enhanced ECL strategy, providing a robust pathway for chiral discrimination and detection of chiral molecules.

Modulating Oxygen Reduction Behaviors on Nickel Single-Atom Catalysts to Probe the Electrochemiluminescence Mechanism at the Atomic Level

Luminol-dissolved O₂ electrochemiluminescence (ECL)-sensing platforms have been widely developed for sensitive and reliable detection, while their actual ECL mechanisms are still in controversy due to the involved multiple reactive oxygen species (ROS). Different from the structural complexity of nanomaterials, well-defined single-atom catalysts (SACs) as coreaction accelerators will provide great prospects for investigating the ECL mechanism at the atomic level. Herein, two carbon-supported nickel SACs with the active centers of Ni-N₄ (Ni-N₄/C) and Ni-N₂O₂ (Ni-N₂O₂/C) were synthesized as efficient coreaction accelerators to enhance the ECL signals of a luminol-dissolved O₂ system. By modulating the surrounding environment of the center metal atoms, their corresponding oxygen reduction behaviors can be well controlled to selectively produce intermediate ROS, giving a great chance to study the following ECL process. According to the experimental and calculated results, the superoxide radical (O₂^•-) acts as the main radical for the ECL reaction and the Ni-N₄/C catalyst with the four-electron pathway to activate dissolved O₂ is preferential to enhance ECL emission.

Dual-Signaling Electrochemical Ratiometric Method for Competitive Immunoassay of CYFRA21-1 Based on Urchin-like Fe3O4@PDA-Ag and Ni3Si2O5(OH)4-Au Absorbed Methylene Blue Nanotubes

A novel ratiometric electrochemical (EC) sensing platform was established for sensitive immunoassay of target cytokeratin 19 fragment 21-1 (CYFRA21-1) biomarker by combining competitive immunoreaction and multisignal output. This immunosensor utilized Ag nanoparticles (NPs)-functionalized urchin-like Fe₃O₄@polydopamine (u-Fe₃O₄@PDA-Ag) as a matrix to immobilize CYFRA21-1 antigens and methylene blue (MB)-absorbed Ni₃Si₂O₅(OH)₄-Au nanotubes (NTs) to label the anti-CYFRA21-1 (Ab). During the competitive immunoreaction, square wave voltammetric (SWV) current changes of Ag NPs from u-Fe₃O₄@PDA-Ag indicator and MB from Ni₃Si₂O₅(OH)₄-Au/MB indicator are relevant to the dosage of CYFRA21-1-acquired Ni₃Si₂O₅(OH)₄-Au/MB/Ab. More importantly, numerous CYFRA21-1 loaded stably on u-Fe₃O₄@PDA-Ag exhibited strong competitive capacity toward the target-CYFRA21-1 to combine Ni₃Si₂O₅(OH)₄-Au/MB/Ab, causing sensitive changes in the ratio of two measured SWV currents. Prominently, "ΔI = ΔI_MB + |ΔI_Ag NPs|" (ΔI_MB and |ΔI_Ag NPs| represents the change values of the oxidation peak currents of MB and Ag NPs, respectively) could be regarded as significantly amplifying the signal response and ultimately improving the sensitivity of CYFRA21-1 detection, from which we derived a wide dynamic range from 500 fg/mL to 50 ng/mL and a low detection limit of 0.39 pg/mL (S/N = 3). This work may exert a profound impact on monitoring other biomarkers in early diagnosis of diseases.

Nitrogen Vacancy Engineering in Graphitic Carbon Nitride for Strong, Stable, and Wavelength Tunable Electrochemiluminescence Emissions

As an attractive electrochemiluminescence (ECL) emitter, graphitic carbon nitride (CN) still suffers from weak and unstable ECL signals for its poor conductivity and the occurrence of electrode passivation. In this study, a simple nitrogen vacancy (NV) engineering strategy has been developed for the improvement of ECL performances (intensity and stability) for the first time. In comparison to pristine CN (RSD = 51.98% for 10 continuous scan), ca. 60 times amplification in ECL intensity and 70 times enhancement in ECL efficiency for CN modified with NVs (CN-NVs) were obtained. In addition, more stable ECL emissions (RSD = 0.53%) were achieved for CN-NV-550 by thermal treatment of pristine CN in a N₂ atmosphere for another 2 h at 550 °C. The mechanism study for the vital role of NVs on the ECL of CN-NVs revealed that NVs can not only facilitate electron transfer to amplify the ECL intensity but also serve as the electron trap to inhibit electrode passivation. More interestingly, a series of CN-NVs exhibited a tunable ECL wavelength range from 470 to 516 nm with different NV contents. Moreover, their ECL spectra showed an obvious red-shift of the wavelength with their corresponding fluorescence spectra. These findings confirmed that the ECL emissions of CN-NVs were susceptible to the relevant surface states of NVs. Our work may open up a promising pathway for improving ECL performances of CN and create new possibilities for multitarget simultaneous detection based on ECL and construction of color tunable light-emitting devices.

An electrochemiluminescence energy resonance transfer system for highly sensitive detection of brombuterol

In this work, an electrochemiluminescence resonance energy transfer (ECL-RET) system was established based on the modified graphite phase carbon nitride to detect brombuterol residues in food. The ultrasonic-assisted acidification exfoliation modification improved the conductivity and specific surface area of the graphite phase carbon nitride (g-C₃N₄). In addition, the carboxylated g-C₃N₄ nanosheets as ECL donors and the Au-Ag alloy nanoparticles as ECL acceptors could respectively directly carry antigen and antibody. Therefore, the trouble of introducing additional bridge molecules was avoided. A competitive immunoassay strategy was used for the detection of brombuterol, where brombuterol in the sample would compete with the coating antigen for the limited binding sites on antibody. The proposed ECL immunosensor for brombuterol detection exhibited high sensitivity with a wide linear range from 0.001 ng mL^-1 to 1000 ng mL^-1 and a low detection limit at 0.31 pg mL^-1. This work adopts a very simple way to design the sensor without losing its sensitivity, bringing convenience to its possible future applications.

Recent advances in co-reaction accelerators for sensitive electrochemiluminescence analysis

In electrochemiluminescence sensing platforms, co-reaction accelerators are specific materials used to catalyze the dissociation of co-reactants into active radicals, which can significantly boost the ECL emission of luminophores.