Self-enhanced Electrochemiluminescence Research Articles

Dual-Ligand Ruthenium Coordination Polymer-Derived Self-Enhanced Electrochemiluminescent Emitters for Sensitive Detection of Procalcitonin.

Ru-based electrochemiluminescence (ECL) coordination polymers are widely employed for bioanalysis and medical diagnosis. However, commonly used Ru-based coordination polymers face the limitation of low efficiency due to the long distance between the ECL reagent and the coreactant dispersed in detecting solution. Herein, we report a dual-ligand self-enhanced ECL coordination polymer, composed of tris(4,4'-dicarboxylic acid-2,2'-bipyridyl) ruthenium(II) dichloride (Ru(dcbpy)32+) as ECL reactant ligand and ethylenediamine (EDA) as corresponding coreactant ligand into Zn2+ metal node, termed Zn-Ru-EDA. Zn-Ru-EDA shows excellent ECL performance which is attributed to the effective intramolecular electron transport between the two ligands. Furthermore, the dual-ligand polymer allows an anodic low excitation potential (+1.09 V) luminescence. The shift in the energy level of the highest occupied molecular orbital (HOMO) upward after the synthesis of the Zn-Ru-EDA has resulted in a reduced excitation potential. The low excitation potential reduced biomolecular damage and the destruction of the modified electrodes. The ECL biosensor has been constructed using Zn-Ru-EDA with high ECL efficiency for the ultrasensitive detection of a bacterial infection and sepsis biomarker, procalcitonin (PCT), in the range from 1.00 × 10-6 to 1.00 × 10 ng·mL-1 with outstanding selectivity, and the detection limit was as low as 0.47 fg·mL-1. Collectively, the dual-ligand-based self-enhanced polymer may provide an ideal strategy for high ECL efficiency improvement as well as designing new self-enhanced multiple-ligand-based coordination in sensitive biomolecular detection for early disease diagnostics.

A dry chemistry-based self-enhanced electrochemiluminescence lateral flow immunoassay sensor for accurate sample-to-answer detection of luteinizing hormone

BackgroundColorimetric lateral flow immunoassay (LFIA) is a widely used point-of-care testing (POCT) technology, while it has entered a bottleneck period because of low detection sensitivity, expensive preparation materials, and incapable quantitative detection. Therefore, it is necessary to develop a novel POCT method that is ultrasensitive, simple, portable, and capable of accurately detecting biomarkers in biofluids daily, particularly for pregnancy preparation and early screening of diseases. ResultIn this work, a novel dry chemistry-based self-enhanced electrochemiluminescence (DC-SE-ECL) LFIA sensor is introduced for accurate POCT of luteinizing hormone (LH). The proposed DC-SE-ECL immunosensor significantly improves the detection sensitivity through the Poly-l-Lysine (PLL)-based SE-ECL probe and cathode modification of closed bipolar electrode (C-BPE). Additionally, a new type of C-BPE configuration is designed for easily performing the LFIA. And, two standalone absorbent pads are symmetrically arranged below the reporting channel of the electrode pad to decease useless residues on the detection pad, which further improves the detection performance. Under optimized conditions, the proposed LFIA sensor has a low limit of detection (9.274 μIU mL−1) and a wide linear dynamic range (0.01–100 mIU mL−1), together with good selectivity, repeatability and storage stability. SignificanceThese results indicate that the proposed DC-SE-ECL method has the potential as a new tool for detecting biomarkers in clinical samples.

N vacancy and self-enhancement induced high anodic electrochemiluminescence of 3D g-C3N4 for sensitive staphylococcus aureus analysis

Here, 3D g-C3N4 with dense N vacancy in its 3D porous interconnected open-framework was synthesized, and the co-reactive 3-(dibutylamino)propylamine (DBAPA) was further covalently coupled onto the surface, resulting in a strong self-enhanced anodic electrochemiluminescence (ECL). Through introduction of high-density N vacancy, for the obtained 3D g–C3N4–NV, the band gap was broadened and the electrical conductivity was enhanced, realizing an obvious ECL improvement. Moreover, after the covalent binding of co-reactive DBAPA, the obtained 3D g–C3N4–NV-DBAPA exhibited a more intensive self-enhanced ECL signal due to the higher co-reaction efficiency originated from shorter electron transfer distance and lower energy loss. Based on the high initial signal of the proposed 3D g–C3N4–NV-DBAPA, a sensitive ECL biosensor with signal “on-off” was fabricated in assistance with multiple horizontal ordered hybridization chain reaction (HO-HCR). Through orderly fixing the reacted DNA chains on the Y-shape DNA structure on the electrode could effectively decrease diffusion process and improve the reaction efficiency of HCR process, resulting in the formation of numerous long horizontal double-strand DNA that could immobilize abundant ferrocene-doxorubicin (Fc-Dox) with ECL quenching effect. Meanwhile, compared to the traditional vertical HCR, the HO-HCR could make the quench reagent closer to the ECL emitter on the electrode surface and obtain a more effective quenching effect to enhance the sensing sensitivity. As a result, the proposed ECL biosensor archived the sensitive measurement of staphylococcus aureus with a detection limit of 10.3 aM.

Highly Active Coreactant-Capped and Water-Stable 3D@2D Core-Shell Perovskite Quantum Dots as a Novel and Strong Self-Enhanced Electrochemiluminescence Probe.

Self-enhanced electrochemiluminescence (ECL) probes have attracted more and more attention in analytical chemistry for their significant simplification of the ECL sensing operation while improving the ECL sensing sensitivity. However, the development and applications of self-enhanced ECL probes are still in their infancy and mainly suffer from the requirement of a complicated synthesis strategy and relatively low self-enhanced ECL activity. In this work, we took advantage of the recently emerged perovskite quantum dots (PQDs) with high optical quantum yields and easy surface engineering to develop a new type of PQD-based self-enhanced ECL system. The long alkyl chain (C18) diethanolamine (i.e., N-octadecyldiethanolamine (ODA)) with high ECL coreactant activity was selected as a capping ligand to synthesize an ODA-capped PQD self-enhanced ECL probe. The preparation of the coreactant-capped PQDs is as simple as for the ordinary oleylamine (OAm)-capped PQDs, and the obtained ODA-capped PQDs exhibit very strong self-enhanced ECL activity, 82.5 times higher than that of traditional OAm-capped PQDs. Furthermore, the prepared ODA-PQDs have a unique nanostructure (ODA-CsPbBr3@CsPb2Br5), with the highly emissive 3D CsPbBr3 PQD as the core and the water-stable 2D CsPb2Br5 as the shell, which allows ODA-PQDs to be very stable in aqueous media. It is envisioned that the prepared ODA-3D@2D PQDs with the easy preparation method, strong self-enhanced ECL, and excellent water stability have promising applications in ECL sensing.

A novel self-enhanced ECL-RET aptasensor based on the bimetallic MOFs with homogeneous catalytic sites for kanamycin detection

The inappropriate use of antibiotics undoubtedly poses a potential threat to public health, creating an increasing need to develop highly sensitive tests. In this study, we designed a new type of porphyrin metal-organic frameworks (Fe TCPP(Zn) MOFs) with homogeneous catalytic sites. The ferric-based metal ligands of Fe TCPP(Zn) MOFs acted as co-reaction accelerators, which effectively improved the conversion efficiency of H2O2 on the surface of MOFs, then increased the concentration of •OH surrounding porphyrin molecules to achieve self-enhanced electrochemiluminescence (ECL). Based on this, an aptasensor for the specific detection of kanamycin (KAN) in food and environmental water samples was constructed in combination with resonance energy transform (RET), in which Fe TCPP(Zn) MOFs were used as luminescence donor and AuNPs were used as acceptor. Under the best conditions, there was a good linear relationship between the ECL intensity and the logarithm of KAN concentration with a detection limit of 0.28 fM in the range of 1.0 × 10−7–1.0 × 10−13 M, demonstrating satisfactory selectivity and stability. At the same time, the complexity of the detection environment was reduced, which further realized the reliable analysis of KAN in milk, honey and pond water. Overall, this innovative self-enhanced ECL strategy provides a novel approach for constructing efficient ECL systems in MOFs, and also extends the application of MOFs to the analysis and detection of trace antibiotics in food and the environment.

Co-Reactive Ligand In Situ Engineered Gold Nanoclusters with Ultra-Bright Near-Infrared Electrochemiluminescence for Ultrasensitive and Label-Free Detection of Carboxylesterase Activity.

Ultrasensitive and accurate monitoring of carboxylesterase (CE) activity is extremely crucial for the early diagnosis of hepatocellular carcinoma (HCC), which is still a considerable challenge. Herein, using a co-reactive ligand engineering strategy, ultra-bright near-infrared (λmax = 830 nm) and self-enhanced electrochemiluminescence (ECL) Au nanoclusters (NCs) were in situ prepared with 2-(diethylamino) ethanethiol (DEAET) as a co-reactive ligand. Remarkably, the co-reactive ligand not only acts as a stabilizer like traditional ligands but also plays a crucial role as a co-reactant to ensure a confinement effect to shorten the charge transfer distance and increase the local concentration, significantly improving the collision efficiency between the electrogenerated free radicals. Consequently, the DEAET Au NCs exhibited a record and stable anodal ECL without the addition of an exogenous co-reactant, dramatically superior to classical Au NCs and Ru(bpy)32+ with a certain amount of the co-reactant. As a proof of concept, a convenient and label-free CE biosensor was innovatively constructed using 1-naphthyl acetate as a selective substrate, achieving ultrasensitive detection for CE activity with a low limit of detection of 9.1 × 10-7 U/L. Therefore, this work not only paves a co-reactive ligand engineering strategy for in situ preparation of high-efficiency metal NCs but also provides an ultrasensitive and convenient platform for the early diagnosis of HCC.

Sulfur vacancy defects mediated CdZnTeS@BC heterojunction: Artificial intelligence-assisted self-enhanced electrochemiluminescence molecularly imprinted sensing of CTC

Environmental pollution caused by tetracycline antibiotics is a major concern of global public health. Here, a novel and portable molecularly imprinted electrochemiluminescence (MIECL) sensor based on smartphones for highly sensitive detection of chlortetracycline (CTC) has been successfully established. The high-performance ECL emitter of biomass carbon (BC) encapsulated CdZnTeS (CdZnTeS@BC) was successfully synthesized by hydrothermal. The enhanced ECL performance was ascribed to the introduction of the BC and increased the overall electrical conductivity of the nanoemitter, as well as increased the number of sulfur vacancies and doping on the surface of the emitter based on density functional theory calculations. An aniline-CTC molecular imprinted polymer was synthesized on the surface of the CdZnTeS@BC modified electrode by in-situ electropolymerization. The decrease in MIECL signal was attributed to the increase in impedance effect. The MIECL nanoplatform enabled a wide linear relationship in the range of 0.05–100 μmol/L with a detection limit of 0.029 μmol/L for spectrometer sensors. Interestingly, the light emitted during the MIECL reaction can be captured by a smartphone. Thus, machine learning was used to screen the photos that were taken, and color analysis was carried out on the screened photos by self-developed software, thus achieving a portable, convenient, and intelligent sensing mode. Finally, the sensor obtains satisfactory results in the detection of actual samples, with no significant differences from those of liquid chromatography.

Self-enhanced Electrochemiluminescence Luminophore Based on Pd Nanocluster-Anchored Metal Organic Frameworks via Ion Annihilation for Sensitive Cell Assay of Human Lung Cancer.

Electrochemiluminescence (ECL) has attracted significant interest in the analysis of cancer cells, where the ruthenium(II)-based emitter demonstrates urgency and feasibility to improve the ECL efficiency. In this work, the self-enhanced ECL luminophore was prepared by covalent anchoring of Pd nanoclusters on aminated metal organic frameworks (Pd NCs@MOFs), followed by linkage with bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) (RuP). The resultant luminophore showed 214-fold self-magnification in the ECL efficiency over RuP alone, combined by promoting the interfacial photoelectron transfer. The enhanced mechanism through ion annihilation was critically proved by controlled experiments and density functional theory (DFT) calculations. Based on the above, a "signal off" ECL biosensor was built by assembly of tyrosine kinase 7 (PTK-7) aptamer (Apt) on the established sensing platform for analysis of human lung cancer cells (A549). The built sensor showed a lower detection limit of 8 cells mL-1, achieving the single-cell detection. This work reported a self-enhanced strategy for synthesis of advanced ECL emitters, combined by exploring the ECL biosensing devices in the single-cell analysis of cancers.

Facile fabrication of silica nanoparticles with incorporation of AIEgen and coreactant as self-enhanced electrochemiluminescence probes for sensitive immunoassay of microcystin-LR

Microcystin-LR (MC-LR) is an algae toxin that poses a serious threat to human health because of its multiorgan toxicity, genotoxicity, and carcinogenicity. Herein, we develop an electrochemiluminescent (ECL) immunosensor for MC-LR detection on the basis of aggregation-induced ECL (AIECL)-assisted self-enhancement strategy. The probe used in this assay is prepared by simultaneously encapsulating AIEgens (namely 1,1,2,2-tetra(4-carboxylbiphenyl)ethylene (H4TCBPE) and its coreactant 2-(dibutylamino)ethanol (DBAE)) into silica to form ternary H4TCBPE@SiO2-DBAE nanoparticles. DBAE can function as a catalyzer to accelerate the in situ formation of SiO2 matrix and an intracoreactant to react with H4TCBPE for the generation of an intense ECL emission as a result of shortened electron transfer pathway and decreased energy loss. We further prepare a biocompatible and electroactive Ti3C2Tx/MoS2/Au hybrid that acts as the immuosensing substrate to accelerate interfacial electron transfer and conjugate the captured antibody (Ab1). Both Ab1-coated Ti3C2Tx/MoS2/Au and antibody (Ab2)-labeled H4TCBPE@SiO2-DBAE can interact with target MC-LR to obtain a sandwich immunosensor. This immunosensor enables quantitative detection of MC-LR antigen with a detection limit of 31 fg/mL and a broad linear range from 50 fg/mL to 10 ng/mL. The proposed strategy opens up a new avenue to fabricating new self-enhanced ECL emitters for sensitive monitoring of environmental microcystins.

Nanoconfined Cathodic Electrochemiluminescence for Self-Sensitized Bioimaging of Membrane Protein.

Self-enhanced electrochemiluminescence (ECL) can be achieved via the confinement of coreactants and ECL emitters in a single nanostructure. This strategy has been used for the design of anodic ECL systems with amine compounds as coreactants. In this work, a novel confinement system was proposed by codoping positively charged ECL emitter tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)32+) and negatively charged coreactant peroxydisulfate (S2O82-) in silica nanoparticles. The codoping process could be performed by introducing S2O82- in cationic poly(diallyldimethylammonium chloride) (PDDA) to form PDDA@S2O82- and then encapsulating it and Ru(bpy)32+ in the Triton X-100 vesicle followed by the hydrolysis of tetraethyl ortosilicate, surface modification, and demulsification. The obtained RuSSNs exhibited good homogeneity, excellent monodispersity, acceptable biocompatibility, and 2.9-fold stronger ECL emission than Ru(bpy)32+-doped silica nanoparticles at an equal amount of nanoparticles in the presence of 0.1 M K2S2O8. Thus, an in situ self-sensitized cathodic ECL imaging method was designed for the monitoring of glycoprotein on living cell membranes. This work provides a new way for the modification, enhancement, and application of nano-ECL emitters in biological analysis.

A self-enhanced electrochemiluminescence array chip for portable label-free detection of SARS-CoV-2 nucleocapsid protein with smartphone

SARS-CoV-2 antigen detection plays a key role in the rapid diagnosis of COVID-19. However, current clinically used immunoassays are often limited by assay throughput, sensitivity, accuracy, and field operating conditions. To address these challenges, we constructed a self-enhanced electrochemiluminescence (ECL) array chip (SE2AC) for highly sensitive and label-free detection of SARS-CoV-2 nucleocapsid protein (N protein) with a facile and portable assay setup. Firstly, the self-enhanced ECL nanomaterials with inherent film-forming properties were synthesized by co-doping Ru(bpy)32+ and polyethyleneimine (PEI) in silica nanoparticles (Ru/PEI@SiO2). Secondly, a resistance-induced potential difference-based single-electrode electrochemical system (SEES) was adapted to serve as the electrode array to facilitate one-step assembly without the need for chip alignment. Thirdly, the chip electrode array was functionalized with the synthesized self-enhanced ECL emitters and captured antibodies. In addition, a portable detection box equipped with a smartphone was 3D-printed to serve as the chip holder and “dark room” for imaging acquisition. The SE2AC performance was validated with N protein with a limit of detection (LOD) of 0.47 pg/mL in the range of 1–10,000 pg/mL. Furthermore, the chip successfully detected the viral antigen residue as low as 1.92 pg/mL from diluted rehabilitation patients’ serum samples. This is the first study reporting label-free detection of SARS-Cov-2 N protein based on a self-enhanced ECL immunosensor, which provides a novel facile method for highly sensitive diagnosis of COVID-19 with high throughput, portability, and low cost.

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.

An "on-off-on" electrochemiluminescence aptasensor based on a self-enhanced luminophore for ochratoxin A detection.

A highly selective and sensitive "on-off-on" electrochemiluminescence (ECL) aptasensor based on a self-enhanced luminophore was developed for the detection of ochratoxin A (OTA). Specifically, polyethyleneimine functionalized multi-walled carbon nanotubes decorated with gold nanoparticles (AuNPs-PEI-MWCNTs) were used as the electrode matrix to accelerate electron transfer and provide a favorable microenvironment for self-enhanced luminophore loading and ECL signal enhancement. In addition, black phosphorus quantum dots (BPQDs) were used as co-reactants of the ECL reagent tris (2,2'-bipyridyl) ruthenium(II) (Ru(bpy)32+) in ECL experiments, and the reaction mechanism was investigated. The self-enhanced luminophore Ru@SiO2-BPQDs was obtained by encapsulating Ru(bpy)32+ in silica (SiO2) nanoparticles and then combining it with BPQDs through electrostatic interaction. In conventional ECL systems, the emitter and its co-reactants reacted via the inter-nanoparticle pathway, leading tolong distance electron transfer. However, the electron transfer distance in the self-enhanced luminophore was significantly shortened due to the intra-nanoparticle electron transfer pathway because BPQDs and oxidized Ru(bpy)32+ were bound within one nanoparticle, thereby improving ECL efficiency to achieve the first "switch-on" state. Then, the luminophore was quenched using ferrocenes (Fc) modified on anaptamer to achieve the "switch-off" state. Finally, OTA was specifically identified by the adapter, causing Fc to be released from the sensor interface, restoring the ECL intensity to achieve the second "switch-on" state. Under optimal conditions, the aptasensor exhibited good sensitivity, stability, and reproducibility, with a linear detection range from 0.1 to 320ng/mL and a detection limit of 0.03ng/mL. The novel ECL aptasensor provided a common analytical tool for the detection of mycotoxins and other small molecules.

Self-Enhanced Electrochemiluminescence Imaging System Based on the Accelerated Generation of ROS under Ultrasound.

Electrochemiluminescence (ECL) imaging, as an optical technology, has been developed at full tilt in the field of life science and nanomaterials. However, the relatively low ECL intensity or the high co-reactant concentration needed in the electrochemical reaction blocks its practical application. Here, we developed an ECL imaging system based on the rGO-TiO2-x composite material, where the co-reactant, reactive oxygen species (ROS), is generated in situ under the synergetic effect of of ultrasound (US) and electric irradiation. The rGO-TiO2-x composites facilitate the separation of electron (e-) and hole (h+) pairs and inhibit recombination triggered by external US irradiation due to the high electroconductivity of rGO and oxygen-deficient structures of TiO2, thus significantly boosting ROS generation. Furthermore, the increased defects on rGO accelerate the electron transfer rate, improving the electrocatalytic performance of the composite and forming more ROS. This high ultrasonic-electric synergistic efficacy is demonstrated through the enhancement of photon emission. Compared with the luminescence intensity triggered by US irradiation and electric field, an enhancement of ∼20-fold and 10-fold of the US combined with electric field-triggered emission is observed from this composite. Under the optimized conditions, using dopamine (DA) as a model target, the sensitivity of the US combined ECL strategy for detection of DA is two orders of magnitude higher than that of the ECL method. The successful detection of DA at low concentrations makes us believe that this strategy provides the possibility of applying ECL imaging for cellular single-molecule analysis and cancer therapy.

A dry chemistry, ultrasensitive microfluidic fiber material-based immunosensor for electrochemiluminescence point-of-care testing of luteinizing hormone

Luteinizing hormone (LH) is a gonadotropin, and its concentration is closely related to the female ovulation cycle. However, the traditional lateral flow method for LH detection has poor sensitivity and sustainability. In this work, a dry chemistry, ultrasensitive microfluidic fiber material-based immunosensor (μFIS) has been firstly proposed for electrochemiluminescence (ECL) point-of-care testing (POCT) of LH. The μFIS was composed of four-layer fiber material (paper and cloth)-based pads, and was combined with closed bipolar electrode-ECL (CBPE-ECL) to quantitatively detect LH. The CBPE-ECL μFIS not only retained the high sensitivity and wide linear range associated with CBPE-ECL, but also reserved the simplicity and practicality of the lateral flow assay. In addition, a self-enhanced intramolecular ECL probe was incorporated into the μFIS for signal amplification. Under optimized conditions, the μFIS had a very low detection limit (0.125 μIU mL-1) and positive linear relationship (0.001–100 mIU mL-1), together with excellent selectivity, reproducibility and storage stability. Moreover, the CBPE-ECL μFIS was applied to detect LH in human clinical serum samples, and the results had a good correlation with those of clinical samples. These results revealed that the CBPE-CEL μFIS had the potential as a high-performance POCT for LH or other biomarkers.

Highly efficient synthesis of CeO2@g-C3N4 double-shelled hollow spheres for ultrasensitive self-enhanced electrochemiluminescence biosensors

In this work, CeO2@g-C3N4 double-shelled hollow spheres were skillfully synthesized as a novel type self-enhanced electrochemiluminescent (ECL) emitter by a highly efficient outside-in hard template method. Thanks to its great catalytic ability, CeO2 were served as a co-reaction accelerator for improving ECL performance of the hollow g-C3N4 spheres (HCNSs)/S2O82− system. In addition, the self-enhanced ECL emitter is designed as a complex containing a co-reaction accelerator and a luminophore to shorten the electron transfer path, which decreases the energy loss of the luminophore significantly. More importantly, the unique double-shelled hollow structure not only greatly decreases the inner filtering effect, but also maximizes the utilization efficiency of the ECL luminophores by increasing a CeO2 shell inside the HCNSs as co-reaction accelerator, effectively enhancing the ECL intensity. Under the optimal conditions, the designed ECL immunosensor showed excellent performance in the determination of CA19-9 with a linear range of 0.50 mU mL−1 –500.00 U mL−1 and a low detection limit of 0.039 mU mL−1. Importantly, the resulting biosensor has good stability, high sensitivity and reliable reproducibility, suggesting its potential application in clinical research.

Dry Chemistry-Based Bipolar Electrochemiluminescence Immunoassay Device for Point-of-Care Testing of Alzheimer-Associated Neuronal Thread Protein

In this study, we developed, for the first time, a novel dry chemistry-based bipolar electrochemiluminescence (ECL) immunoassay device for point-of-care testing (POCT) of Alzheimer-associated neuronal thread protein (AD7c-NTP), where the ECL signals were automatically collected and analyzed after the sample and buffer solutions were manually added onto the immunosensor. The proposed immunoassay device contains an automatic ECL analyzer and a dry chemistry-based ECL immunosensor fabricated with a screen-printed fiber material-based chip and a three-dimensional (3D)-printed shell. Each pad of the fiber material-based chip was premodified with certain reagents for immunoreaction and then assembled to form the ECL immunosensor. The self-enhanced ECL of the Ru(II)-poly-l-lysine complex and the lateral flow fiber material-based chip make the addition of coreactants and repeated flushing unnecessary. Only the sample and buffer solutions are added to the ECL immunosensor, and the process of ECL detection can be completed in about 6 min using the proposed automatic ECL analyzer. Under optimized conditions, the linear detection range for AD7c-NTP was 1 to 104 pg/mL, and the detection limit was 0.15 pg/mL. The proposed ECL immunoassay device had acceptable selectivity, stability, and reproducibility and had been successfully applied to detect AD7c-NTP levels in human urine. In addition, the accurate detection of AD7c-NTP and duplex detection of AD7c-NTP and apolipoprotein E ε4 gene were also validated. It is believed that the proposed ECL immunoassay device may be a candidate for future POCT applications.

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.

Highly sensitive electrochemiluminescence biosensor based on novel TiO2-porphyrin organic framework with self-enhanced luminescent property

The electrochemiluminescence (ECL) signal strength in the ternary ECL system depends on the efficiency of the coreactants, and the coreaction accelerator has been demonstrated to be an effective catalyst. A self-enhanced ECL strategy was used in which the coreaction accelerator was generated in situ during the synthesis of luminophores in our work. A composite material (Zn-TCPP-TiO2-Ti3C2) integrating a luminophore (Zn-TCPP) and a coreaction accelerator (TiO2 NPs) was synthesized by a solvothermal method. The probe designed with tripropylamine-modified AuNPs (TPrA@AuNPs) was immobilized on Zn-TCPP-TiO2-Ti3C2 by the sandwich structure. The immobilization not only increased the concentration of the coreactant at the electrode interface but also greatly shortened the electron transport distance with the luminophore and coreaction accelerator, thus further improving the ECL signal. Compared with the TPrA@AuNPs/Zn-TCPP system, the ECL signal of TPrA@AuNPs/Zn-TCPP-TiO2-Ti3C2 was amplified 3.5 times. Under the optimal conditions, the designed ECL biosensor exhibited a wide dynamic range from 1.0 × 102 to 1.0 × 105 particles μL−1 and a low detection limit of 11 particles μL−1 for exosomes. Importantly, this work not only developed a simple and ultrasensitive exosome detection system but also provided a novel possibility for the practical application of porphyrin-based metal-organic frameworks (Por-MOFs) in biological analysis.

Dual-quenching effects of methylene blue on the luminophore and co-reactant: Application for electrochemiluminescent-electrochemical ratiometric zearalenone detection

Methylene blue (MB) is a common multifunctional indicator, which can be applied as a quencher for electrochemiluminescence (ECL) analysis as well as a classical redox probe. Although it is relatively prevalent for MB to study the mechanism with Ru-based luminophores in ECL systems, there are few studies on the effects between MB and co-reactants. In this work, we proposed the first investigation of MB on the luminophore and co-reactant of the self-enhanced ECL composites (nitrogen-doped graphene quantum dots on Ru(bpy)32+-doped silica nanoparticles, NGQDs-Ru@SiO2), respectively. The relatively narrow ECL spectrum of luminophore (Ru@SiO2) and the suitable ultraviolet–visible absorption spectrum of MB led to the ECL resonance energy transfer between them, meanwhile the appropriate energy levels among them facilitated the electron transfer, resulting in a decreased ECL signal (quench mode I). Additionally, the co-reactant (NGQDs) was prone to π-π conjugation with MB due to its abundant π-electrons, which reduced the concentration of NGQDs’ intermediates and triggered a weakened ECL signal (quench mode II). Therefore, the dual-quenching effects are ingeniously integrated and designed in one ECL-electrochemical (ECL-EC) ratiometric aptasensor for zearalenone detection, for demonstrating its efficacy in enhancing the sensitivity, which is 4.8-fold higher than Ru@SiO2 alone. This innovative ratiometric aptasensor achieved a relatively wide linear range from 1.0 × 10−15 to 5.0 × 10−8 g mL−1, and obtained a low detection limit of 8.5 × 10−16 g mL−1. Our proposed dual-quenching interactions between MB and NGQDs-Ru@SiO2 will open a new prospective for ECL-EC ratiometric aptasensor, which further broaden the application in sensitive and precise analysis of mycotoxins.