High Electrochemiluminescence Research Articles

Alkynyl Ligands Templated Assemblies of Silver Nanoclusters with Exceptional Electrochemiluminescence Activity for Pancreatic Cancer Specific tsRNAs Measurement.

Proper manipulation of the ligand complex on the motifs of metal nanoclusters (MNCs) to form an ordered self-assembly is an effective approach to enhance the electrochemiluminescence (ECL) emission of MNCs. We report a facile approach for the preparation of self-assembled AgNCs (AgNCsAssy) induced by alkynyl ligands with enhanced ECL and stability. The formation of these AgNCsAssy was simultaneously driven by the diverse coordination modes of alkynyl ligands with Ag and intercluster interactions, for which it was found that the para-substituted alkynyl ligands exhibited apparently irregular nanoparticles, while the monosubstituted counterparts were present in the form of ribbons. The calculations revealed that the energy gap between the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) played a crucial role in their ECL emissions because of the substituent effects, especially, the low-lying LUMO levels could help to enhance the ECL emission. Moreover, mechanistic studies revealed that both the coreactant and alkynyl ligands made significant contributions to the ECL performance. Concurrently, the CRISPR-associated proteins (CRISPR-Cas) 12a system shows great potential in biosensing applications due to the advantages of easy design and precise targeting. As a proof of concept, we integrated the cascade amplification of catalytic hairpin assembly (CHA) circuit and the collateral cleavage activity of CRISPR-Cas12a to construct an ultrasensitive ECL biosensor for pancreatic cancer (PC)-specific tsRNAs, with a detection limit of 3.33 fM. This work is not only instructive for the synthesis of self-assembled MNCs with high ECL activities but also contributes to the understanding of the ECL mechanism of self-assembled MNCs.

Solid-phase electrochemiluminescence immunosensing platform based on bipolar nanochannel array film for sensitive detection of carbohydrate antigen 125.

Development of simple solid-phase electrochemiluminescence (ECL) immunosensor with convenient fabrication for high-performance detection of tumor biomarkers is crucial. Herein, a solid-phase ECL immunoassay was constructed based on a bipolar silica nanochannel film (bp-SNA) modified electrode for highly sensitive detection of carbohydrate antigen 125 (CA 125). Inexpensive and readily available indium tin oxide (ITO) electrode was used as the supporting electrode for the growth of bp-SNA. bp-SNA consists of a bilayer SNA film with different functional groups and charge properties, including negatively charged inner layer SNA (n-SNA) and positively charged outer layer SNA (p-SNA). The nanochannels of bp-SNA were used for the immobilization of ECL emitter tris(bipyridine)ruthenium(II), while the outer surface was utilized for constructing the immunorecognition interface. Due to the dual electrostatic interaction composed of electrostatic attraction from n-SNA and electrostatic repulsion from p-SNA, ECL emitter could be stably confined within bp-SNA, providing stable and high ECL signals to the modified electrode. After amino groups on the outer surface of bp-SNA were derivatized with aldehyde groups, recognition antibodies could be covalently immobilized, and an immunosensor was obtained after blocking nonspecific sites. When CA 125 binds to the antibodies on the recognition interface, the formed complex reduces the diffusion of the co-reactant tripropylamine (TPrA) to the supporting electrode, decreasing the ECL signal. Based on this mechanism, the constructed immunosensor can achieve sensitive ECL detection of CA 125. The linear detection range is from 0.01 to 100U/mL, with a detection limit of 4.7mU/mL. CA 125 detection in serum is also achieved. The construction immunosensor has advantages including simple and convenient fabrication, high stability of the immobilized emitter, and high selectivity, making it suitable for CA 125 detection.

Self-Enhanced Electrochemiluminesence of Dye-Doped Polymer Dots for Coreactant-Free Visualized Detection of Iodide Ions.

The monitoring of radioactive iodide levels is of great significance in environmental science and cancer radiotherapy. In this work, a high-throughput, radiation-resistant, and visualized electrochemiluminescence (ECL) strategy was developed for detection of iodide ions. Herein, the hydrophobic ruthenium derivative (Ru(bpy)3[B(C6F5)4]2) (bpy = bipyridyl) was doped in tertiary amine-coupled polymer dots (N-PFO Pdots) to synthesize self-enhanced Pdots (Ru@Pdots), which showed extremely high ECL intensity in absence of coreactant. Due to the efficient ECL resonance energy transfer between Ru(bpy)3[B(C6F5)4]2 and N-PFO, the Ru@Pdots exhibited 18 times higher ECL intensity compared with bare N-PFO Pdots. Besides, Ru@Pdots also showed 220-times higher ECL intensity compared with Ru(bpy)3[B(C6F5)4]2 doped coreactant-dependent Pdots (Ru@PFO Pdots). Using Ru@Pdots as ECL emitters, an ECL imaging array was designed for iodide ion detection, which exhibited a detection range of 0.8 nM-4 μM and a limit of detection of 0.1 nM. In this strategy, iodide ions were oxidized as iodide free radicals on the surface of the electrode, which could further consume the nitrogen radical of Ru@Pdots and effectively quench the ECL signal. This method also showed good specificity, radiation-resistant performance, and accuracy in actual seawater sample testing, which indicated its value in marine environmental monitoring, nuclear security, and cancer radiotherapy.

Electrochemiluminescence of Carbon Dots and Nitrogen-Doped Carbon Dots from a Microwave-Assisted Method

This research focuses on the use of carbon dots (CDs) and nitrogen-doped carbon dots (NCDs) synthesized using a microwave-assisted method as electrochemiluminescence (ECL) luminophores. CDs have been synthesized using citric acid, while various concentrations of nitrogen-doped CDs have been successfully obtained by varying the amount of urea from 1 to 3 g with citric acid to produce NCD1, NCD,2 and NCD3. The ECL mechanism of CDs and NCDs on screen-printed electrodes has been studied using cyclic voltammetry (CV). ECL emission from as-prepared CDs and NCDs was observed in PBS with potassium persulfate (K2S2O8) as a co-reactant. The addition of potassium chloride (KCl) as a supporting electrolyte displays fast electroreduction of CDs and K2S2O8 to expedite the generation of CDs and peroxydisulfate radicals that simultaneously increase ECL intensity. Furthermore, as the concentration of nitrogen-doped CDs increases, so does the intensity of the ECL. NCD3 shows the highest ECL intensity by an increment of 86.4% in comparison to CDs in PBS with the addition of K2S2O8 and KCl. Finally, optimization of ECL measurement was carried out in terms of CV potential range, concentration of luminophore, supporting electrolyte, and co-reactant using NCD3 luminophore. The CV potential range at 0 to -2 V shows 50 mV of early CV reverse onset potential that resulted in an increase of 52.9% ECL intensity. Meanwhile, 30x dilution of NCD3, 0.1 M of supporting electrolyte KCl, and 0.1 M of co-reactant K2S2O8 show the optimum value to obtain high ECL intensity.

Recent Advances in Luminophores for Enhanced Electrochemiluminescence Analysis.

Electrochemiluminescence (ECL) detection is widely applied in many fields, including chemical measurement, biological analysis, and clinic tests, due to its high sensitivity. Currently, the fast development of many new electrochemical luminophores is continuously improving the ECL-based detection ability. Besides the enhancement of luminescence emission for a high detection sensitivity, minimizing the effect of co-reactants on ECL detection and achieving multiple analysis in one sample are also the main directions in this field. This review focuses on a summary of recently prepared new luminophores to achieve the three aims mentioned above. Especially, the review is composed by three parts, focusing on the luminophores or materials with high ECL efficiency, self-enhancing properties, and multi-color ECL luminophores. The fabrication of biosensors using these molecules is also reviewed to exhibit the advances in biological applications.

Phosphopeptide-bridged NH2-TiO2-mediated carbon dots self-enhancing and electrochemiluminescence microsensors for label-free protein kinase A detection.

A novel electrochemiluminescence (ECL) method was developed for determination of protein kinase A (PKA) ultra-sensitively based on amidated nano-titanium (NH2-TiO2) embellished carbon dots (Mg@N-CDs) fluorescent probe, which integrated the target recognition and ECL signal enhancement. The Cys-labeled kemptides were employed to build a serine-rich synthetic substrate-heptapeptide (Cys-kemptide) on the Au-electrode surface. Then, the PKA-induced biosensor was triggered as a signal switch to introduce the large amounts of TiO2 decorated Mg@N-CD nanohybrid (Ti@NMg-CDs) into AuE/Cys-phosphopeptides for signal output. In particular, the presence of PKA could induce the formation of Cys-phosphopeptides by the catalytic reaction between specific substrate (kemptide) and PKA, which acts as an initiator to link the Ti@NMg-CDs according to the bridge interactions Ti-O-P. In this way, multiple Cys-phosphopeptides were adsorbed onto a single Ti@NMg-CDs, and the Ti@NMg-CDs not only provided high specific selectivity but also large surface area, as well as unprecedented high ECL efficiency. Using this PKA-induced enhanced sensor, the limit of detection of the PKA was 4.89 × 10-4 U/mL (S/N = 3). The proposed ECL biosensor was also universally applicable for the screening of PKA inhibitors and determining of other kinases activity. Our sensing system has excellent performance of specificity and the screening of kinase inhibitors, as well as it will inspire future effort in clinical diagnostics and new drug discovery.

Confinement-enhanced electrochemiluminescence of copper nanoclusters on 3D layered double hydroxide for ultrasensitive detection of GFAP

In this work, the copper nanoclusters (Cu NCs) were confined on 3D layered double hydroxide (3D-LDH) to form Cu NCs@3D-LDH with outstanding electrochemiluminescence (ECL) for constructing ultrasensitive biosensor to detect of glial fibrillary acidic protein (GFAP) implicated in Alzheimer's Disease (AD). More importantly, compared to the individual Cu NCs, Cu NCs@3D-LDH presented strong and stable ECL response, since 3D-LDH could not only gather more Cu NCs but also limit the intramolecular free motion to reduce nonradiative transition for obtaining high ECL intensity. In addition, the improved cascade amplification method combining proximity ligation assay (PLA) with DNAzyme could transform tiny amount of target protein into a large amount of output DNA to improve sensitivity of biosensor. The ECL biosensor realized ultrasensitive detection of GFAP with the detection limit of 2 ag/mL and it had been successfully applied to the evaluation of GFAP in the serum of patients with neurological diseases. This research offered a general and facile method to improve ECL performance of Cu NCs for sensitive detection of biomarkers for disease diagnosis.

Ultrasensitive electrochemiluminescence biosensing from Cobalt single atom embedded high crystalline g-carbon nitride nanorod

Here, cobalt single-atom (Co SA) was introduced into the structure of the crystalline g-C3N4 nanorod (cry-CNN), which showed rapid electron transfer rate and excellent redox activity, thereby resulting in high electrochemiluminescence (ECL) emission. Compared to bulk g-C3N4, the cry-CNN had higher ECL intensity due to increasing the crystallinity to change the charge transport of electrons in the layer. Besides, benefiting from the unique electronic structure and catalytic activity of Co SA, the obtained Co SA@cry-CNN represented enhanced ECL intensity at a lower negative potential than that of cry-CNN, owing to the Co SA not only accelerated the electron transfer of the cry-CCN in heptazine cavity, but also promoted the co-reactive S2O82- to produce more active intermediate SO4•–. Interestingly, the experimental results showed that the ECL emission of Co SA@cry-CNN was about 23 times higher than that of BCN, and was 5 times higher than that of cry-CNN. Furthermore, using Co SA@cry-CNN as luminophore, a compact and efficient HCR-link-CHA(HLC) cascade amplification strategy was designed to construct a biosensor for detection of microRNA-222, which converted a certain amount of target to a DNA nanonet with plenty of quencher via N cycle of HCR and CHA reaction. The constructed biosensor had good monitoring performance and the limit of detection was as low as 40.0 amol/L. The proposed strategy integrated luminous structural adjustment and co-reaction efficiency improvement could be effectively extended to exploration of other novel ECL materials, and also provided new ideas for the early diagnosis of diseases.

Ultrasensitive Electrochemiluminescence Biosensing Platform Based on Polymer Dots with Aggregation-Induced Emission for Dual-Biotoxin Assay.

Multitarget assay has always been a hot topic in electrochemiluminescence (ECL) methods. Herein, a "on-off-on" ECL aptasensor was developed for the ultrasensitive and sequential detection of possible biological warfare agents, deoxynivalenol (DON) and abrin (ABR). As a luminophore, polymer dots (Pdots) with aggregation-induced emission exhibit high ECL efficiency in the aptasensor, i.e., the signal "on" state. The DON assays mainly depend on ECL quenching due to the efficient quenching effect between ferrocene-H2-ferrocene (Fc-H2-Fc) and Pdots, i.e., the signal "off" state. When the aptasensor is incubated with the oligonucleotide sequence S2 to replace Fc-H2-Fc, obvious ECL recovery occurs, i.e., the signal "on" state, which can be used to sequentially detect ABR. The limit of detection (LOD) for DON is 0.73 fg·mL-1 in the range of 5.0 to 50 ng·mL-1; and the LOD for ABR is ∼0.38 pg·mL-1 in the range of 1.25 pg·mL-1 to 1.25 μg·mL-1. The as-designed ECL aptasensor exhibits good stability and reproducibility, high specificity, and favorable practicality. Therefore, this work provides a new approach for assays of DON and ABR in food safety and can be used as a model to design an ultrasensitive ECL biosensor for multitarget detection.

Highly Electroactive Co2+-Based Metal-Organic Frameworks as an Efficient Coreaction Accelerator for Amplifying Near-Infrared Electrochemiluminescence of Gold Nanoclusters in Biomarkers Immunoassay.

Metal nanoclusters (NCs) as a new kind of luminophore have acquired sufficient interest, but their widespread application is restricted on account of their relatively low electrochemiluminescence (ECL) efficiency. Then, aqueous metal NCs with high ECL efficiency were strongly anticipated, especially for the ultrasensitive analysis of biomarkers. Herein, a near-infrared (NIR) ECL biosensing strategy for the test of neuron-specific enolase (NSE) was proposed by utilizing N-acetyl-l-cysteine (NAC)- and cysteamine (Cys)-stabilized gold NCs (NAC/Cys-AuNCs) as ECL emitters with the NIR ECL emission around 860 nm and a metal-organic framework/palladium nanocubes (ZIF-67/PdNCs) hybrid as the coreaction accelerator through their admirable electrocatalytic activity. The NIR emission would reduce photochemical injury to the samples and even realize nondestructive analysis with highly strong susceptibility and suitability. Furthermore, the utilization of ZIF-67/PdNCs could improve the ECL response of NAC/Cys-AuNCs by facilitating the oxidation of the coreactant triethylamine (TEA), leading to the production of a larger quantity of reducing intermediate radical TEA•+. Consequently, NAC/Cys-AuNCs with ZIF-67/PdNCs displayed 2.7 fold enhanced ECL emission compared with the single NAC/Cys-AuNCs using TEA as the coreactant. In addition, HWRGWVC (HWR), a heptapeptide, was introduced to immobilize antibodies for the specially binding Fc fragment of the antibodies, which improved the binding efficiency and sensitivity. As a result, a "signal-on" immunosensor for NSE analysis was obtained with an extensive linear range of 0.1 to 5 ng/mL and a low limit of detection (0.033 fg/mL) (S/N = 3). This study provides a wonderful method for the development of an efficient nondestructive immunoassay.

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.

Single-Atom Iron Doped Carbon Dots with Highly Efficient Electrochemiluminescence for Ultrasensitive Detection of MicroRNAs.

Herein, single-atom iron doped carbon dots (SA Fe-CDs) were successfully prepared as novel electrochemiluminescence (ECL) emitters with high ECL efficiency, and a biosensor was constructed to ultrasensitively detect microRNA-222 (miRNA-222). Importantly, compared with the conventional without single-atom doped CDs with low ECL efficiency, SA Fe-CDs exhibited strong ECL efficiency, in which single-atom iron as an advanced coreactant accelerator could significantly enhance the generation of reactive oxygen species (ROS) from the coreactant S2O82- for improving the ECL efficiency. Moreover, a neoteric amplification strategy combining the improved strand displacement amplification with Nt.BbvCI enzyme-induced target amplification (ISDA-EITA) could produce 4 output DNAs in every cycle, which greatly improved the amplification efficiency. Thus, a useful ECL biosensor was built with a detection limit of 16.60 aM in the range of 100 aM to 1 nM for detecting traces of miRNA-222. In addition, miRNA-222 in cancer cell lysate (MHCC-97L) was successfully detected by using the ECL biosensor. Therefore, this strategy provides highly efficient single-atom doped ECL emitters for the construction of sensitive ECL biosensing platforms in the biological field and clinical diagnosis.

Bright luminescent Zn2GeO4:Mn NP/MXene hydrogel-based ECL biosensor for glioblastoma diagnosis

In this work, miRNA-10b in the glioblastoma (GBM) tumor tissues has been detected by a novel electrochemiluminescence (ECL) biosensor. Firstly, a new kind of bright luminescent Zn2GeO4:Mn NPs were prepared as ECL nanoprobe, which possessed high fluorescence quantum yield and ECL quantum efficiency. Secondly, Ti3C2 MXene hydrogel (MXG) have been developed as the sensing interface. The MXG retained the inherent biocompatibility and mechanical features of hydrogel. Furthermore, the uniform distribution of metallic Ti3C2 MXene in the hydrogel microstructure provided the good conductivity and multiple binding sites for biomolecules. MXene also can promote the separation of the electrons and holes to accelerate the electron-transfer rate and improve ECL efficiency. Due to these synergistic effects, the screen printed electrode was successfully modified with MXG as sensing platform to enhance the ECL intensity of Zn2GeO4:Mn NP, which greatly improved the detection efficiency and facilitated the high-throughput analysis. Finally, the toehold mediated strand displacement (TMSD) strategy was employed with then biosensor to detect miRNA-10b with the range of 10 fM to 1 nM. The limit of detection was 5 fM. This ECL biosensor has been used to analyze miRNA-10b expression in GBM tumor tissues, which possessed the great potential value for clinical diagnosis.

Enhanced Aggregation-Induced Delayed Electrochemiluminescence Triggered by Spatial Perturbation of Organic Dots.

Development of highly efficient, heavy-metal-free electrochemiluminescence (ECL) materials is attractive but still challenging. Herein, we report an aggregation-induced delayed ECL (AIDECL) active organic dot (OD) composed of a tert-butoxy-group-substituted benzophenone-dimethylacridine compound, which shows high ECL efficiency. The resultant ODs exhibit 2.1-fold higher ECL efficiency compared to control AIDECL-active ODs. Molecular stacking combined with theoretical calculations suggests that tert-butoxy groups effectively participate in the intermolecular interactions, further inhibiting the molecular motions in the aggregated states and thus accelerating radiative decay. On the basis of these ODs exhibiting excellent ECL performance, a proof-of-concept biosensor is constructed for the detection of miR-16 associated with Alzheimer's disease, which demonstrates excellent detection ability with the limit of detection of 1.7 fM. This work provides a new approach to improve the ECL efficiency and enriches the fundamental understanding of the structure-property relationship.

In situ generated CdTe quantum dot-encapsulated hafnium polymer membrane to boost electrochemiluminescence analysis of tumor biomarkers.

Exploring the construction of an interface with bright emission, fabulous stability, and good function to develop high-performance electrochemiluminescence (ECL) biosensors for tumor biomarkers is in high demand but faces a huge challenge. Herein, we report an oriented attachment and in situ self-assembling strategy for one-step fabrication of CdTe QD-encapsulated Hf polymer membrane onto an ITO surface (Hf-CP/CdTe QDs/APS/ITO). Hf-CP/CdTe QDs/APS/ITO is fascinating with excellent stability, high ECL emission, and specific adsorption toward ssDNA against dsDNA and mononucleotides (mNs). These interesting properties make it an ideal interface to rationally develop an immobilization-free ECL biosensor for cancer antigen 125 (CA125), used as a proof-of-concept analyte, based on target-aptamer recognition-promoted exonuclease III (Exo III)-assisted digestion. The recognition of ON by CA125 leads to the formation of CA125@ON, which hybridizes with Fc-ssDNA to switch Exo III-assisted digestion, decreasing the amount of Fc groups anchored onto the electrode's surface and blocking electron transfer. As compared to the case where CA125 was absent, significant ECL emission recovery is determined and relies on CA125 concentration. Thus, highly sensitive analysis of CA125 against other biomarkers was achieved with a limit of detection down to 2.57pg/mL. We envision this work will provide a new path to develop ECL biosensors with excellent properties, which shows great potential for early and accurate diagnosis of cancer.

A sensitive immunosensor via Pd@Au0.85Pd0.15 in situ electrocatalysis generating H2O2 for quenching electrochemiluminescence of Ir(pbi)2(acac)@Ti3C2Tx MXene-PVA

The establishment of rapid target analysis methods for cytokeratin fragment antigen 21-1 (CYFRA 21-1) is urgently needed. [Ir(pbi)2(acac)] (pbi = 2-(4-bromophenyl)-1-hydrogen -benzimidazole, acac = acetylacetonate) as traditional electrochemiluminescence (ECL) luminophores has been confined due to its non-negligible dark toxicity and poor water solubility leading to poor biocompatibility and electrical conductivity as an organic molecule. Hence, to overcome this limitation, [Ir(pbi)2(acac)] can be effectively loaded on the polyvinyl alcohol hydrogel modified Ti3C2Tx MXene surface (Ir@Ti3C2Tx-PVA) as sensing platform which can emit high ECL signals. Then, a quenching strategy was proposed to fabricate an ECL sandwich immunosensor using H2O2 as quencher molecules which can generated by Pd@Au0.85Pd0.15. Especially, the generation of O2 to H2O2 can be achieved through a two-electron (2e–) reaction pathway by Pd@Au0.85Pd0.15, to overcome the restriction that the H2O2 was virtually impossible to label or immobilize on the non-enzyme nanomaterials. The proposed ECL assay achieves a response to CYFRA 21-1 within the range of 0.1 pg/mL–100 ng/mL, with a detection limit of 8.9 fg/mL (S/N = 3). This work provided a feasible tactic to seek superior-performance ECL luminophore and quencher consequently set up a novel means to makeup ultrasensitive ECL biosensor, which extended the utilization potential of Ir(pbi)2(acac) in ECL assays.

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.

Ultrasensitive Electrochemiluminescence Biosensor Based on Efficient Signal Amplification of Copper Nanoclusters Induced by CaMnO3 for CD44 Trace Detection.

Metal nanoclusters (Me NCs) have become a research hotspot in the field of electrochemiluminescence (ECL) sensing analysis. This is primarily attributed to their excellent luminescent properties and biocompatibility along with their easy synthesis and labeling characteristics. At present, the application of Me NCs in ECL mainly focuses on precious metals, whose high cost, to some extent, limits their widespread application. In this work, Cu NCs with cathode ECL emissions in persulfate (S2O82-) were prepared as signal probes using glutathione as ligands, which exhibited stable luminescence signals and high ECL efficiency. At the same time, CaMnO3 was introduced as a co-reaction promoter to increase the ECL responses of Cu NCs, thereby further expanding their application potential in biochemical analysis. Specifically, the reversible conversion of Mn3+/Mn4+ greatly promoted the generation of sulfate radicals (SO4•-), providing a guarantee for improving the luminescence signals of Cu NCs. Furthermore, a short peptide (NARKFYKGC) was introduced to enable the fixation of antibodies to specific targets, preventing the occupancy of antigen-binding sites (Fab fragments). Therefore, the sensitivity of the biosensor could be significantly enhanced by releasing additional Fab fragments. Considering the approaches discussed above, the constructed biosensor could achieve sensitive detection of CD44 over a broad range (10 fg/mL-100 ng/mL), with an ultralow detection limit of 3.55 fg/mL (S/N = 3), which had valuable implications for the application of nonprecious Me NCs in biosensing analysis.

High-performance electrochemiluminescence of self-assembled multi-resonance thermally activated delayed fluorescence nanoparticles

In this paper, the synthesis of thermally activated delayed fluorescence nanoparticles (TADF NPs) is reported using a micelle-confined soft template self-assembly. With vaporing organic solvent in this system, TADF NPs with a diameter of about 500 nm were obtained. The main advantage is to nanoencapsulate these TADF molecules with an amphiphilic polymer. As demonstrated, air-stable nanoparticles with efficient TADF properties are realized in water. The application of these as-prepared TADF NPs as a kind of alternative electrochemiluminescent (ECL) material has also been investigated. The triplet-harvesting ability combined with excellent redox properties endows as-prepared TADF NPs with a high ECL efficiency of 10.82%, which is a marked enhancement over previous results. Therefore, ECL materials with similar behavior to reported TADF materials in this article are desirable in applications such as ECL sensing, imaging, and light-emitting devices.

Polymerized carbon dots with high electrochemiluminescence efficiency and long wavelength ECL emission for ultrasensitive detection of MicroRNA-222

Herein, a new electrochemiluminescence (ECL) biosensor was constructed with highly efficient polymerized carbon dots (PCDs) as ECL emitter and the improved localized catalytic hairpin assembly (L-CHA) as signal amplifier for ultrasensitive detection of microRNA-222 (miRNA-222). Impressively, compared to the traditional carbon dots with inefficient blue region ECL emission, PCDs with N, O co-dope and large conjugated π-system showed high electrical conductivity, narrow band gap and strong radiative transition, which could exhibit high ECL efficiency to improve the sensitivity of detection and long wavelength ECL emission to achieve deep tissue penetration for reducing biological damage. Furthermore, the trace target miRNA-222 could be efficiently converted into large amounts of output DNA labelled with the quencher dopamine (S-DA) through the L-CHA reaction to significantly enhance the target amplification efficiency for further improving the sensitivity of detection. Thus, the ECL biosensor could achieve the ultrasensitive detection of miRNA-222 from 100 aM to 100 pM with the detection limit of 76 aM. Therefore, this work proposed a novel CDs with high ECL efficiency and long wavelength ECL emission, which not only was used to build an ultrasensitive biosensor for biomolecules detection in clinical diagnosis, but also served as a potential emitter for ECL bioimaging.