Coreaction Accelerator Research Articles

Ultrasensitive electrochemiluminescence sensor for the detection of synthetic cannabinoids based on perovskite as coreaction accelerator and light-scattering effects of photonic crystals

As is common knowledge, a strong electrochemiluminescence (ECL) signal is required to ensure the high sensitivity of trace target detection. Here, a dual signal amplification strategy by integrating of perovskite and photonic crystal was fabricated for quantitative synthetic cannabinoids (AB-PINACA) detection based on Zr-connected PTCA and TCPP (PTCA-TCPP) with excellent ECL performance as luminophores. On the one hand, the co-reaction accelerator perovskite (LaCoO3) improved the effective electroactive area of the electrode and promoted the decomposition of K2S2O8, resulting in a stronger ECL signal value. On the other hand, polystyrene inverse opal (PIOPCs) formed after the swelling of PS microspheres not only taken advantage of the light scattering effect and excellent catalytic property of photonic crystals to amplify the ECL signal, but also could be used as a binder to fix LaCoO3 and PTCA-TCPP on the electrode surface to generate unprecedented ECL response and stable ECL signals. Subsequently, the detection substance AB-PINACA was loaded on the electrode surface via the amide bond with the luminophores PTCA-TCPP, thus quenching the ECL signal, so as to realize the sensitive detection of synthetic cannabinoids. Under the optimal conditions, the proposed sensor achieved highly sensitive AB-PINACA detection with a dynamic range from 1.0 × 10−12 to 1.0 × 10−3 g/L and the detection limit was 1.1 × 10−13 g/L, which had great application potential in the detection of synthetic cannabinoids.

Cobaltous sulfide/S-doped Ti3C2 MXene nanocomposites with coreaction acceleration effect for high-performance luminol electrochemiluminescence sensing by coupling micro-nano bubbles-mediated amplification strategy

Exploration of a feasible method to enhance dissolved oxygen (DO) content and design a supplementary accelerator to accelerate the reduction efficiency of DO in the luminol-DO system was significantly meaningful for developing a high-performance electrochemiluminescence (ECL) sensing platform. Herein, a novel luminol-DO ECL system was designed by coupling the micro-nano bubbles (MNBs) and CoS2/S-Ti3C2 heterostructure for sensitive detection of chloramphenicol (CAP). Specifically, the introduction of MNBs could increase the DO content in PBS solution and the special conditions caused by MNBs rupture generated abundant reactive oxygen species (ROS). Meanwhile, CoS2/S-Ti3C2 could be used as advanced co-reaction accelerator to accelerate the reduction efficiency of DO, which could produce more ROS. Remarkably, the ECL intensity of the as-fabricated system not only revealed an 8.7-fold enhanced signal, but also displayed a more stable ECL signal compared to individual luminol-DO system. With the assistance of CAP aptamer, the as-fabricated luminol − DO system exhibited a wide linear range from 0.1 fM to 10 pM with an ultra-low detection limit of 105 fM (S/N = 3), and it performed excellent stability, reproducibility and sensitivity, so as to be applied to real sample monitoring. This strategy not only provided a new avenue to design more efficient MXene-based co-reaction accelerator, but also paved the way for the development of high-performance luminol − DO ECL system.

A novel micron europium cluster coordination polymer as a strong electrochemiluminescent emitter for accurate and sensitive detection of tetracycline.

In this work, a self-luminescent micron europium cluster coordination polymer (Eu-CCP) cathode electrochemiluminescence (ECL) emitter is first reported. The mass percentage of Eu in Eu-CCP is 50.1%, indicating that Eu-CCP has a high-nucleation luminescence center. In addition, our Eu-CCP possesses a stable and efficient ECL red emission performance, and the intensity is approximately 6.5-fold higher than that of the traditional tris(2,2'-bipyridyl)ruthenium(II) dichloride. The enhancement of Eu-CCP luminescence in our system is due to the following reasons: (1) the mixed ligand and high nuclear europium luminescent center can cooperate to improve the quenching effect induced by water or hydroxyl groups; and (2) external coreaction accelerator and coreactant enhancement. We also investigate the application of Eu-CCP in ECL sensors by sensitive detection of tetracycline (TC). The low detection limit (73.5 fmol·L-1), high selectivity, good stability and satisfactory recoveries indicate that our ECL strategy can be used to detect TC accurately and sensitively.

A double-quenching paperclip ECL biosensing platform for ultrasensitive detection of antibiotic resistance genes (mecA) based on Ti3C2 MXene-Au NPs as a coreactant accelerator

The global spread of environmental biological pollutants, such as antibiotic-resistant bacteria and their antibiotic resistance genes (ARGs), has emerged as a critical public health concern. It is imperative to address this pressing issue due to its potential implications for public health. Herein, a DNA paperclip probe with double-quenching function of target cyclic cleavage was proposed, and an electrochemiluminescence (ECL) biosensing platform was constructed using Ti3C2 MXene in-situ reduction growth of Au NPs (TCM-Au) as a coreactant accelerator, and applied to the sensitive detection of ARGs. Thanks to the excellent catalytic performance, large surface area and Au–S affinity of TCM-Au, the ECL performance of CdS QDs have been significantly improved. By cleverly utilizing the negative charge of the paperclip nucleic acid probe and its modification group, double-quenching of the ECL signal was achieved. This innovative approach, combined with target cyclic amplification, facilitated specific and sensitive detection of the mecA gene. This biosensing platform manifested highly selective and sensitive determination of mecA genes in the range of 10 fM to 100 nM and a low detection limit of 2.7 fM. The credible detectability and anti-interference were demonstrated in Yangtze river and Aeration tank outlet, indicating its promising application toward pollution monitoring of ARGs.

AuPt Nanodonuts as a Novel Coreaction Accelerator and Luminophore for a Label-free Electrochemiluminescence Aptasensor.

Novel and effective coreaction accelerators are of great importance in electrochemiluminescence (ECL) systems. In this work, novel AuPt nanodonuts, i.e., SnS2 quantum dots (QDs)/Cys-AuPt heterogeneous nanorings (NRs), serve as both a highly effective coreaction accelerator and the luminophore in a label-free ECL aptasensor. The novel AuPt nanodonuts were formed by decorating SnS2 QDs onto AuPt NR surfaces, which would promote the production of more coreactant intermediate in the SnS2 QDs/K2S2O8 system. As a result, the ECL performance was greatly improved. Meanwhile, l-cysteine (l-Cys) played an important role in the combination between AuPt NRs and SnS2 QDs, and the nanodonuts served as the matrix to load numerous lincomycin (Lin) aptamers. Under optimal conditions, the ECL aptasensor exhibited ultrasensitive detection of Lin from 1 to 0.1 pg/mL with a limit of detection (LOD) of 0.7 fg/mL (1.72 fM)..

3D hierarchical ZnNiO2 nanoflowers as a novel co-reaction accelerator to fabricate stable and highly sensitive biosensor for the methotrexate assay

Herein, polyaniline (PANI) and reduced graphene oxide (rGO) as nanoprobes couple with graphitic carbon nitride to form rGO@g-C3N4-PANI nanocomposite, which exhibits good synergetic enhancement impact on the ECL signal of g-C3N4. Moreover, ZnNiO2 nanoflowers (ZnNiO2 NFs) are firstly used as co-reaction accelerators to remarkably enhance the ECL emission of rGO@g-C3N4-PANI in this work. In the presence of ZnNiO2 NFs, a significant ECL signal enhancement of 15780 a.u. is observed, which is 4 times stronger than that of the rGO@g-C3N4-PANI. Owing to the excellent electronic conductivity and the ability to avoid the deposition of positively charged reduction products, the ZnNiO2 NFs can effectively prevent electrode passivation, thus the rGO@g-C3N4-PANI/ZnNiO2 system emits stable and strong ECL signal. A sensitive ECL sensor has been constructed for the quantitative detection of methotrexate (MTX) of the real blood sample by quenching the ECL signal. Under the optimal conditions, the sensor exhibits a superior linear range from 1 pM to 10 μM and a low detection limit of 0.24 pM (S/N = 3). The proposed ECL signal amplification strategy can be an effective analytical tool for trace detection of targets in biological systems.

Signal-Enhanced Immunosensor-Based MOF-Derived ZrO2 Nanomaterials as Electrochemiluminescence Emitter for D-Dimer Detection.

Metal oxide nanomaterials have garnered significant attention in the field of electrochemiluminescence (ECL) sensing due to their efficient, stable, and nontoxic properties. However, the current research on metal oxide nanomaterials has primarily focused on their cathodic luminescence properties, with limited reports on their anodic ECL properties. In this study, we utilized MOF-derived ZrO2 nanomaterials as luminophores to generate stable anodic ECL signals in the presence of the coreactant tripropylamine (TPrA). Additionally, a signal-enhancing immunosensor was developed to analyze D-dimer by incorporating the coreaction accelerator Cu-doped TiO2 (TiO2-Cu). The ZrO2 synthesized by calcining UiO-67 demonstrated nontoxicity and biocompatibility, exhibiting efficient and stable ECL emission in a TPrA solution. The inclusion of TiO2-Cu as a coreaction accelerator in the immunosensor resulted in the formation of a ternary system of ZrO2/TiO2-Cu/TPrA. The Cu doping effectively narrowed the bandgap of TiO2 and enhanced its conductivity. As a substrate, TiO2-Cu reacted with more TPrA, generating sufficient free radicals to effectively enhance the ECL signal of ZrO2. In this article, a short peptide ligand, NFC (NARKFYKGC), was designed to immobilize antibodies and maintain the activity of antigen-binding sites during the construction of the immunosensor. The developed immunosensor was used for the accurate detection of D-dimers, with a wide linear range of 0.05-600 ng/mL and a low detection limit of 21 pg/mL..

Selenium and nitrogen co-doped carbon dots with highly efficient electrochemiluminescence for ultrasensitive detection of microRNA

In this work, selenium and nitrogen co-doped carbon dots (SeN-CDs) possessing highly efficient electrochemiluminescence (ECL) and excellent biocompatibility were synthesized as a new emitter with S2O82− as a coreactant for constructing a biosensor to detect microRNA-221 (miRNA-221) sensitively. Notably, the SeN-CDs exhibited superior ECL performance compared with the N-doped CDs, in which selenium with excellent redox activity served as a coreaction accelerator for facilitating the electroreduction of S2O82− to significantly improve ECL efficiency. Furthermore, target-induced T7 exonuclease (T7 Exo)-assisted double cycle amplification strategy could convert traces of target miRNA-221 into large amounts of output DNA to capture three-dimensional (3D) nanostructures (DTN-Au NPs-DOX-Fc) loaded with large amounts of ECL signal quencher. The constructed biosensor could realize ultrasensitive detection of miRNA-221 and has a low detection limit reaching 2.3 aM, with a successful application to detect miRNA-221 in lysate of Hela and MHCC97-L cancer cell. This work explored a novel method to strengthen the ECL performance of CDs to construct an ECL biosensing platform with sensitive detecting of biomarkers and disease diagnosis.

Potential-resolved electrochemiluminescence biosensor for simultaneous determination of multiplex miRNA

The multi-target simultaneous detection strategy based on potential-resolved electrochemiluminescence (ECL) has still been a research hotspot in analytical science, but the limited selection of ECL luminophores hinders the development of this field. Herein, polyethyleneimine functionalized perylene derivatives (PTC-PEI) and luminol functionalized gold nanoparticles (Lu–Au NPs) possessed significantly resolved emission potentials as ECL luminophore. The ternary ECL system was constructed with MoS2 nanoflowers and K2S2O8 as the coreaction accelerator and coreactant respectively, which significantly improved the cathode ECL emission of PTC-PEI. Simultaneously, the anode coreaction accelerator ZnO nanoflowers could promote the anode coreactant dissolved O2 reduction, and extremely enhanced the anode ECL emission of Lu–Au NPs. The proposed strategy addressed the major technical challenge of cross interference and competition of the coreactants for dual-biomarker detection, thus enabling accurate detection of miRNA-205 and miRNA-21 from 10 fM to 100 nM, with detection limits of 2.57 and 1.15 fM, respectively. In general, this work achieved a single-step synchronous detection of dual biomarkers, providing a new idea for the ECL detection of multiple biomarkers, and having potential value in the clinical diagnosis.

Signal "On-Amplified-Off" Strategy Based on Hafnium Dioxide Nanomaterials as Electrochemiluminescence Emitters for Progesterone Detection.

When consumed, excess progesterone (P4)─found in food and the environment─can lead to severe illnesses in humans. Therefore, quantitative analysis of P4 is critical for identifying its hazardous levels. In this study, a novel signal "on-amplified-off" P4 detection mode was proposed, which was based on the utilization of hafnium oxide (HfO2) as a unique electrochemiluminescence (ECL) emitter, produced by calcining UiO-66(Hf). This is the first time that HfO2 has been used as an ECL emitter. HfO2 displayed excellent conductivity and a high specific surface area, allowing it to connect with numerous aptamers and produce a "signal-on" effect. Ni-doped ZnO (Ni-ZnO) acted as a coreaction accelerator, enhancing the ECL strength of HfO2 by generating more tripropylamine radicals. cDNA was labeled with Ni-ZnO, and Ni-ZnO was linked to the aptamer via base complementary pairing, affording "signal-amplified". The presence of the target molecule P4 instigated a specific binding process with the aptamer, triggering the shedding of cDNA-Ni-ZnO and resulting in "signal-off". This novel "on-amplified-off" strategy effectively improved the sensitivity and specificity of P4 analysis, introducing a practical method for detecting biomolecules beyond the scope of this study, which holds immense potential for future applications.

An electrochemiluminescence sensor for ultrasensitive detection of Hg2+ based on self-enhanced Ru-QDs@SiO2 luminophore and P6ICA/MoS2 as co-reaction accelerator

An electrochemiluminescence (ECL) biosensor combined with DNA signal amplification technology was constructed for Hg2+ detection based on an efficient self-enhanced ECL luminophore (Ru-QDs@SiO2) and a novel co-reaction accelerator poly(indole-6-carboxylic acid)/molybdenum disulfide (P6ICA/MoS2). The Ru-QDs@SiO2 nanosphere was prepared by co-encapsulating the donor CdS QDs and acceptor Ru(bpy)32+ into a silica nanoparticle, which enabled ECL resonance energy transfer (ECL-RET) to occur inside the Ru-QDs@SiO2 nanospheres, thereby shortening the electron transfer path between donor and acceptor, further enhancing the ECL signal intensity. Additionally, P6ICA/MoS2 was used as a novel co-reaction accelerator for the detection of Hg2+. P6ICA/MoS2 exhibits excellent conductivity and a well-defined hierarchical structure, making it to effectively facilitate the generation of more co-reactive free radicals, and provide a good substrate for fixing abundant cDNA. Meanwhile, introducing the Exo III-assisted target recycling strategy further amplifies the ECL signal, simplifying the construction process. The as-fabricated ECL biosensor exhibits an ultrasensitive detection ability of Hg2+ with a broad liner detection range from 100 nM ∼ 0.1 fM, and the detection limit can be down to 0.07 fM. Moreover, this ECL biosensor shows excellent stability, reproducibility and selectivity, and is successfully utilized for the detection of Hg2+ in seawater with good performance.

A novel ECL aptasensor for ultra-highly sensitive detection of patulin based on terbium organic gels as Co-reaction accelerator in a 3, 4, 9, 10-perylenetetracarboxylic acid/K2S2O8 system

Patulin (PAT), a fungal metabolite, which mainly exists in various moldy fruits, is greatly harmful to human. However, there are still many unsolved problems in the current detection of PAT. In the work, an ultra-highly sensitive and effective monitoring strategy for PAT was explored based on a novel electrochemiluminescence (ECL) aptasensor. Here, 3, 4, 9, 10-perylenetetracarboxylic acid (PTCA) was chosen as luminophore and terbium (Tb) metal organic gel (MOG) was prepared as a co-reaction accelerator. The MOG displayed a large surface area for immobilization of sufficient PTCA to catalyze co-reactant K2S2O8 to generate more sulfate radical anions (SO4• −), thus accelerating the electron-transfer (ET) rate to facilitate ECL efficiency. In the presence of PAT, the ECL signal was greatly quenched, which could be attributed to the specific binding effect between PAT aptamer and PAT. Based on this process, a wide range of PAT concentrations from 0.1 fg·mL−1 to 0.1 μg·mL−1 and a low detection limit of 0.02 fg·mL−1 (S/N = 3) were analyzed. The aptasensor showed excellent detection properties for trace patulin in terms of selectivity, sensitivity, stability, reproducibility and practicability. The designing ideas could serve as a model for the application of metal organic gels to design ultra-highly sensitive ECL platforms for food safety.

Enhancing Ru(bpy)32+@TMU-13 electrochemiluminescence for ultrasensitive detection of AFP by a signal amplification strategy based on flower-like Au NPs/CoFe LDO/MoS2 NFs as double coreaction accelerators

A signal amplification strategy based on a Ru(bpy)32+ luminescence functionalized metal-organic framework (MOF) and double coreaction accelerators was developed for the detection of alpha-fetoprotein (AFP) by electrochemiluminescence (ECL). The high porosity and rich functional groups of MOF can improve the binding rate of biomolecules. Therefore, Ru(bpy)32+ was encapsulated by the three-dimensional hierarchical porous MOF TMU-13 as the luminescence nanoreactor. The complex exhibits stable and excellent luminescence efficiency and rich carboxyl functional groups, which can support enough antibodies. In addition, the process of K2S2O8 reduction was promoted by double coreaction accelerators, including MoS2 grown in CoFe LDOs in situ and in situ reduction of gold nanoparticle (AuNPs) nanoflower structures (AuNPs/CoFe LDO/MoS2 NFs), the ECL signal in the cathode was significantly increased. Under optimal conditions, the established AFP detection method exhibited a wide linear range of 10−5 ng·mL−1 to 100 ng·mL−1, and the detection limit was as low as 3.23 fg·mL−1. Importantly, this strategy shows great potential for application in the field of bioanalysis.

An ultrasensitive ratiometric aptasensor based on the dual-potential electrochemiluminescence of Ru(bpy)32+ in a novel ternary system for detection of Patulin in fruit products.

To sensitively monitor trace-level of toxic patulin (PAT), an ultrasensitive PAT ratiometric aptasensor based on the dual-potential electrochemiluminescence (ECL) of Ru(bpy)32+ was first proposed. Noteworthily, Ru(bpy)32+-doped trimetallic nanocube (Ru@Tri) innovatively integrated the luminophore and cathode coreaction accelerator (CCA), which could generate strong cathodic ECL in the existence of low concentration of K2S2O8. Simultaneously, anthocyanin-derived carbon quantum dots (anth-CQDs) prepared from purple potato skins was first served as a green anodic coreactant. And SiO2-coated anth-CQDs (anth-CQDs@SiO2) exhibited excellent performance for enhancing anodic ECL of Ru@Tri. Based on this, a novel ternary ECL system was established. In the presence of PAT, the ECL intensity ratio of anode to cathode (IECL-A/IECL-C) was significantly increased, and a low detection limit of 0.05pgmL-1 was obtained. Moreover, when proposed method and high performance liquid chromatography (HPLC) were simultaneously applied to series of fruit products, the obtained results were completely consistent, reflecting its practicability.

Bioinspired Single-Atom Sites Enable Efficient Oxygen Activation for Switching Anodic/Cathodic Electrochemiluminescence.

Exploring advanced co-reaction accelerators with superior oxygen reduction activity that generate rich reactive oxygen species (ROS) has attracted great attention in boosting luminol-O2 electrochemiluminescence (ECL). However, tuning accelerators for efficient and selective catalytic O2 activation to switch anodic/cathodic ECL is very challenging. Herein, we report that enzyme-inspired Fe-based single-atom catalysts with axial N/C coordination structures (FeN5, FeN4(C) SACs) can generate specific ROS for cathodic/anodic ECL conversion. Mechanistic studies reveal that FeN5 sites prefer to produce highly active hydroxyl radicals and afford direct cathodic luminescence by promoting the cleavage of O-O bonds through N-induced electron redistribution. In contrast, FeN4(C) sites tend to produce superoxide radicals, resulting in inefficient anodic ECL. Benefiting from the enhanced cathodic ECL, FeN5 SAC-based immunosensor was constructed for the sensitive detection of cancer biomarkers.

Zirconium dioxide as electrochemiluminescence emitter for D-dimer determination based on dual-quenching sensing strategy

The ECL emission of simple and stable zirconium dioxide nanomaterials has always been a blank slate in the ECL sensors field. In this work, zirconium dioxide (ZrO2)-titanium dioxide (TiO2)-gold nanoparticle (AuNPs) composite (ZT-Au), a novel self-enhanced ECL emitter, was introduced the system of dual-quenching ECL immunosensor. The anodic luminescence of ZrO2 in the system of tripropylamine (TPrA) as a co-reagent was first reported and explored. Meanwhile, TiO2 was designed into the ECL scheme as a co-reaction accelerator to form the ZrO2/TPrA/TiO2 ternary system, which can efficiently amplify the ECL signal of the emitter. In addition, cuprous oxide-triaminophenol (Cu2O-APF) as the quencher was devoted to the dual-quenching sensing strategy. The dual-quenching mechanism that effectively boosted the immunosensor sensitivity was adequately investigated and conjectured in this paper. The sensing model based on the luminophor ZT-Au and the quencher Cu2O-APF was utilized for the detection of D-dimer, a reliable marker for the diagnosis and evaluation of thrombotic diseases. The short peptide ligands NARKFYKGC (NFC) with efficient biological affinity were used to site-directionally capture antibodies for adequately protecting the activity of antigen binding sites during the construction of the immunosensor. The implemented immunosensor was equipped with a broad linear range of 0.01–500 ng/mL and a low detection limit of 3.6 pg/mL. The original methodology opens up the field of vision for the detection of additional biomarkers.

An electrochemiluminescence immunosensor with double co-reaction accelerators based on Ag3PO4@EuPO4-AgNP for detecting squamous cell carcinoma antigen.

This study aimed to design a sandwich electrochemiluminescence (ECL) immunosensor with double co-reaction accelerators for sensitively detecting squamous cell carcinoma antigen (SCCA). First, silver orthophosphate (Ag3PO4) nanoparticles were modified on the surface of EuPO4 nanowires to improve their poor dispersibility/solubility. At the same time, EuPO4 was used as a co-reaction accelerator to catalyze S2O82- to produce more intermediates (SO4•-), significantly enhancing the ECL signal of Ag3PO4. Ag nanoparticles (AgNP) modified on Ag3PO4@EuPO4 composite nanomaterials were used not only as linkers of luminescence groups and biomarkers but also as a co-reaction accelerator to effectively enhance ECL signal. The designed ECL immunosensor displayed several advantages, including good stability and reproducibility. Under the optimal conditions, its linear range in detecting SCCA was 0.0001-50ng·mL-1, the detection limit was 25fg·mL-1 (S/N = 3), the recovery was 96.6-100.4%, and the relative standard deviation was less than 4.8%. It was successfully applied todetect SCCA in human serum.

“Blocking-effect” detection strategy of clenbuterol by molecularly imprinted electrochemiluminescence sensor based on multiple synergistic excitation of AgNW luminophores signal with highly active BNQDs@AuNFs nanoscale co-reaction accelerator

A molecularly imprinted electrochemiluminescence sensor (MIECLS) is constructed to selectively detect clenbuterol (CLB) based on boron nitride quantum dots@gold nanoflowers/silver nanowires (BNQDs@AuNFs/AgNWs). The abundant amino and hydroxyl groups on the surface of the BNQDs generate an electrostatic self-assembly effect with the multi-tipped spatial structure of AuNFs, constituting a novel nanoscale co-reaction accelerator (NCRA) with high activity and large load capacity. An NCRA embedded in the network structure of the AgNW luminophores significantly promotes the reduction of peroxydisulfate (S2O82−) to sulfate anion radicals (SO4−•) through the catalysis of amino groups and boron radicals (B•) and the electron acceleration of AuNFs while also reducing the reaction distance between SO4−• and AgNWs−•, realizing the multiple synergistic amplification of the electrochemiluminescence (ECL) signal. Imprinted cavities in the molecularly imprinted polymers (MIPs) prepared by electropolymerization can generate a “blocking-effect” by recognizing CLB, realizing ECL signal quenching. Analytical results indicate that the established MIECLS detects CLB in a line concentration range of 0.5–50000 nM and detection limit of 0.00693 nM. The spiked recoveries are 85.90%–97.77%, with the relative standard deviations (RSD) under 5.1%, consistent with those of high-performance liquid chromatography (HPLC). This work demonstrates that an efficient NCRA can significantly enhance the output of the ECL signal in collaboration with the original luminophore, providing a new method to realize the ultra-detection of targeted substances by MIECLS.

Electrochemiluminescence Immunosensors Based on ECL-RET Triggering between Mn SANE/PEI-Luminol and PtCu/h-MPF for Ultrasensitive Detection of CEA.

In this paper, a novel donor-acceptor pair was creatively proposed based on the principle of electrochemiluminescence resonance energy transfer (ECL-RET): luminol immobilized on polyethyleneimine (PEI)-functionalized manganese-based single-atom nanozymes (Mn SANE/PEI-luminol, donor) and a PtCu-grafted hollow metal polydopamine framework (PtCu/h-MPF, acceptor). A quenched ECL immunosensor was constructed for the ultrasensitive analysis of carcinoembryonic antigen (CEA). Mn SANE, as an efficient novel coreaction accelerator with the outstanding performance of significantly activating H2O2 to produce large amounts of ROS, was further modified by the coreactant PEI, which efficiently immobilized luminol to form a self-enhanced emitter. As a result, the electron transport distance was effectively shortened, the energy loss was reduced, and luminol achieved a high ECL efficiency. More importantly, PtCu-grafted h-MPF (PtCu/h-MPF) was proposed as a novel quencher. The UV-vis spectra of PtCu/h-MPF partially overlap with the ECL spectra of Mn SANE/PEI-luminol, which can effectively trigger the ECL-RET behavior between the donor and the acceptor. The multiple quenching effect on Mn SANE/PEI-luminol was achieved, which significantly improved the sensitivity of the immunosensor. The prepared immunosensor exhibited good linearity in the concentration range of 10-5 to 80 ng/mL. The results indicate that this work provides a new method for the early detection of CEA in clinical diagnosis.

An electrochemiluminescence immunosensor based on signal magnification of luminol using OER-activated NiFe2O4@C@CeO2/Au as effective co-reaction accelerator

In this work, a novel, label-free electrochemiluminescence (ECL) immunosensor was constructed for the ultrasensitive detection of carbohydrate antigen 15–3 (CA15-3) by the combined use of NiFe2O4@C@CeO2/Au hexahedral microbox and luminol luminophore. The synthesis of the co-reaction accelerator (NiFe2O4@C@CeO2/Au) was related to the calcination of FeNi-based metal–organic framework (MOF), as well as the ingrowth of CeO2 nanoparticles and modification of Au nanoparticles. To be specific, the electrical conductivity will be boosted due to the Au nanoparticles, the synergetic effect generated between CeO2 and calcination FeNi-MOF could offer better activity of oxygen evolution reaction (OER). Herein, the NiFe2O4@C@CeO2/Au hexahedral microbox as a co-reaction accelerator has excellent OER activity and production of reactive oxygen species (ROS), thus increasing the ECL intensity of luminol in a neutral medium without other co-reactants such as H2O2. Because of these benefits, the constructed ECL immunosensor was applied to detect CA15-3 as an example under optimum conditions, the designed ECL immunosensor exhibited high-level selectivity and sensitivity for CA15-3 biomarker within a linear response range of 0.01–100 U mL−1 and an ultralow detection limit of 0.545 mU mL−1 (S/N = 3), demonstrating its potentially valuable application in the area of clinical analysis.