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In recent years, carbon‐based quantum dots as luminophores and co‐reactants have aroused broad interest for their ability to function in electrochemiluminescence (ECL) sensors due to their unique features, including excellent biocompatibility, low toxicity, and water solubility. In this mini review, the synthesis methods of carbon‐based quantum dots are firstly introduced. Then, the mechanism of carbon‐based quantum dots as luminophores and co‐reactants and their latest progress application in the detection of heavy metal ions are explored. Finally, the current challenges and potential future development directions of carbon‐based quantum dots in ECL sensing filed for heavy metal ions analysis are summarized. [ABSTRACT FROM AUTHOR]

A label-free electrochemiluminescence sensor based on silica nanoparticles doped with a self-enhanced Ru(bpy) 3 2+-carbon nitride quantum dots luminophore was developed to detect Hg(II). [Display omitted] Herein, a label-free, self-enhanced electrochemiluminescence (ECL) sensing strategy for divalent mercury (Hg(II)) detection was presented. First, a novel self-enhanced ECL luminophore was prepared by combining the ECL reagent tris(2, 2′-bipyridyl) dichlororuthenium(II) hexahydrate (Ru(bpy) 3 2+) and its co-reactant carbon nitride quantum dots (CNQDs) via electrostatic interactions. In contrast to traditional ECL systems where the emitter and its co-reactant underwent an intermolecular reaction, the self-enhanced ECL system exhibited a shortened electron-transfer distance and enhanced luminous efficiency because the electrons transferred from CNQDs to oxidized Ru(bpy) 3 2+ via an intramolecular pathway. Furthermore, the as-prepared self-enhanced ECL material was encapsulated in silica (SiO 2) nanoparticles to generate a Ru-QDs@SiO 2 luminophore. Based on the different affinity of Ru-QDs@SiO 2 nanoparticles for single-stranded DNA (ssDNA) and Hg(II)-triggered double-stranded DNA (dsDNA), a label-free ECL biosensor for Hg(II) detection was developed as follows: in the absence of Hg(II), ssDNA was adsorbed on Ru-QDs@SiO 2 surface via hydrogen bond, electrostatic, and hydrophobic interaction. Thus, quenched ECL signal was observed. On the contrary, in the presence of Hg(II), stable dsDNA was formed and carried the ssDNA separating from Ru-QDs@SiO 2 surface, resulting in most of Ru-QDs@SiO 2 existing in their free state. Therefore, a recovered ECL intensity was obtained. On this basis, Hg(II) was measured by the proposed method in the range of 0.1 nM-10 μM, with a detection limit of 33 pM. Finally, Hg(II) spiked in water samples was measured to evaluate the practicality of the fabricated biosensor. [ABSTRACT FROM AUTHOR]

A novel solid-state electrochemiluminescence (ECL) sensor for 17β-estradiol detection based on an intermolecular hydrogen bonds-induced self-enhanced ECL composite (Ru(dcbpy) 3 2+-NCQDs) was constructed for the first time. • A hydrogen-bonds induced self-enhanced ECL composite was generated on GCE surface. • Superior ECL properties of Ru(dcbpy) 3 2+-NCQDs composite was obtained without signal amplifier. • Excellent analytical performances were acquired using 17β-estradiol as a target. Herein, an induced self-enhanced electrochemiluminescence (ECL) sensor with superior ECL performances was simply fabricated by just dropping the ECL reagent (tris(4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium (II) dichloride, Ru(dcbpy) 3 Cl 2) and coreactant (nitrogen-doped carbon quantum dots, NCQDs) pair onto the surface of glassy carbon electrode. In this strategy, based on the carboxyl (–COOH) groups in Ru(dcbpy) 3 2+ and oxygen, nitrogen-containing groups on NCQDs surface, an intermolecular hydrogen bonds-induced self-enhanced ECL composite was generated in the solid contact layer for the first time. Since Ru(dcbpy) 3 2+ and NCQDs were co-existing in the same composite, the electron-transfer distance between them was shortened and the energy loss was decreased, thereby higher ECL efficiency was acquired. This working process greatly avoided the introduction of signal amplifier and simplified the experimental operation. On this basis, 17β-estradiol (E2) was selected as a target model to fabricate a self-enhanced ECL aptamer sensor for the investigation of its analytical performances. Resultantly, excellent detection properties of E2, including wider linear range of 1.0 × 10-14 − 1.0 × 10-6 mol L-1 and lower detection limit of 1.0 × 10-15 mol L-1 with superior selectivity, were successfully achieved. Finally, E2 spiked into milk powder was quantified to assess the practicability of this sensor. Prospectively, this strategy could be extensively applied for other analytes determination by adjusting the corresponding target aptamers. [ABSTRACT FROM AUTHOR]

The development of bifunctional signal probes based on a single component is highly desirable for sensitive and simple dual-mode detection of Pb2+. Here, novel gold nanocluster-confined covalent organic frameworks (AuNCs@COFs) were fabricated as a bisignal generator to enable electrochemiluminescence (ECL) and colorimetric dual-response sensing. AuNCs with both intrinsic ECL and peroxidase-like activity were confined into the ultrasmall pores of the COFs via an in situ growth method. On the one hand, the space-confinement effect of the COFs closed the ligand motion-induced nonradiative transition channels of the AuNCs. As a result, the AuNCs@COFs exhibited a 3.3-fold enhancement in anodic ECL efficiency compared to the solid-state aggregated AuNCs using triethylamine as the coreactant. On the other hand, due to the outstanding spatial dispersibility of the AuNCs in the structurally ordered COFs, a high density of active catalytic sites and accelerated electron transfer were obtained, leading to the promotion of the enzyme-like catalytic capacity of the composite. To validate its practical applicability, a Pb2+-triggered dual-response sensing system was proposed based on the aptamer-regulated ECL and peroxidase-like activity of the AuNCs@COFs. Sensitive determinations down to 7.9 pM for the ECL mode and 0.56 nM for the colorimetric mode were obtained. This work provides an approach for designing single element-based bifunctional signal probes for dual-mode detection of Pb2+. [Display omitted] • A single element-based bifunctional probe of AuNCs@COFs was prepared firstly. • The probe showed 3.3-fold ECL efficiency than AuNCs due to the confinement of COFs. • The peroxidase-like activity was promoted due to good distribution of AuNCs in COFs pores. • Based on the ECL and peroxidase performances, a dual-mode sensor for Pb2+ was fabricated. [ABSTRACT FROM AUTHOR]

A multifunctional solid-state electrochemiluminescence (ECL) sensing platform based on poly(ethylenimine) (PEI) capped N-doped carbon dots (NCDs@PEI) as novel co-reactant of Ru ( bpy ) 3 2 + nanosheets (RuNSs) was designed for the first time. In this route, RuNSs with large surface-to-volume ratio was used as luminophor, and NCDs@PEI, which was newly synthesized and modified in one step via a facile microwave-assisted method, was served as co-reactant. The as-prepared NCDs@PEI exhibited better catalytic effect to RuNSs than naked NCDs, due to the double enhancement contribution of NCDs and PEI to RuNSs. Simultaneously, reduced graphene oxide (rGO) was further introduced to facilitate the electron transfer and amplify the ECL signal. The developed ECL sensor (NCDs@PEI-rGO/RuNSs/GCE) exhibited desired ECL emission, with about 69-fold enhancement of the ECL intensity in comparison with RuNSs/GCE. When used as ECL probe for dopamine detection, the prepared sensor showed high sensitivity in a wide linear range of 0.01–50 μM with the detection limit of 10 nM. Moreover, the sensing platform also suggested multifunctional application for detecting other compounds including bisphenol A, catechol and hydroquinone. [ABSTRACT FROM AUTHOR]

A novel Ru ( bpy ) 3 2 + -based electrochemiluminescence (ECL) sensing platform, using N-doped carbon nanodots (N–C dots) as co-reactant, was established for the sensitive and selective detection of bisphenol A (BPA). N–C dots not only could enhance the ECL signal, but also significantly improved the reproducibility and stability of Ru ( bpy ) 3 2 + ECL system. The developed ECL sensing system was sensitive to detect BPA based on its efficient quenching effect on Ru ( bpy ) 3 2 + / N − C dots. The N–C dots-enhanced ECL mechanism and BPA-quenched ECL mechanism were investigated. Under the optimum conditions, the inhibited ECL intensity was in good linear relationship versus the concentration of BPA in the range of 0.03–1.0 μM with the detection limit of 10 nM. The relative standard deviation (RSD) for 25 successive measurements with one sensor was 1.1% and for eight different sensors was 2.5%, respectively. The fabricated sensing platform was successfully applied for the detection of BPA in baby bottle and nipple, and relatively satisfactory recoveries were obtained. [ABSTRACT FROM AUTHOR]

Four chiral drugs were enantioseparated by native beta-cyclodextrin (β-CD) and negatively charged carboxymethyl-beta-cyclodextrin (CM-β-CD) using capillary electrophoresis coupled with electrochemiluminescence detection (CE-ECL). Using 50 mM pH 5.5 Tris–H 3 PO 4 with 10 mM CM-β-CD as a running buffer, high resolution efficiency could be obtained. With the help of isothermal titration calorimetry (ITC), nuclear magnetic resonance (NMR) and molecular modeling, the chiral recognition mechanism was comprehensively investigated. Thermodynamic parameters data from ITC revealed that CM-β-CD exhibited stronger binding affinity with analytes than β-CD, and that the driving forces of CM-β-CD responsible for chiral recognition were mainly electrostatic interactions between negatively charged CM-β-CD and positively charged analytes. In addition, from both a macroscopic and microscopic point of view, the results of NMR and molecular modeling investigation adequately confirm the conclusion by comparing the stereochemical structures of complexes. Combination of ITC, NMR and molecular modeling techniques not only can assist CE to investigate the chiral discrimination mechanism, but also can predict and guide CE enantioseparation efficiency conversely. [ABSTRACT FROM AUTHOR]

Abstract: The coupling of end-column tris (2,2′-bipyridyl) ruthenium (II) electrochemiluminescence (ECL) detection with capillary electrophoresis (CE) was developed for the analysis of two antipsychotic drugs, perphenazine (PPH) and fluphenazine (FPH). The parameters related to CE separation and ECL detection, including the detection potential, the buffer pH value and concentration, the separation voltage, and Ru(bpy)3 2+ concentration, were investigated in detail. Under optimum conditions, PPH and FPH were well separated and detected within 11min. The linear ranges were 0.1–5μM for PPH, and 0.1–7.5μM for FPH, respectively. The limits of detection of PPH and FPH were 5 and 10nM (S/N=3). The relative standard deviations (n=3) of the ECL intensity and the migration time were less than 2.5 and 0.65% in a day, and less than 3.4 and 1.7% in different three days. The proposed method was successfully applied to determine PPH and FPH in spiked urine samples with satisfactory results. [Copyright &y& Elsevier]

Signal amplification provides an effective way to improve detection performance. Herein, an ultrasensitive electrochemiluminescence (ECL) aptasensor for Pb2+ detection was developed based on a dual signal-amplification strategy of the abscission of a quencher and the generation of a G-quadruplex by one-step and simultaneous way. Nitrogen-doped carbon quantum dots linked with complementary DNA (cDNA-NCQDs) at the sensing interface was applied as the quencher of a tris(4,4′-dicarboxylic acid-2,2′-bipyridyl)ruthenium(II) (Ru(dcbpy) 3 2+)/tripropylamine system to minimize the ECL signal due to the intermolecular hydrogen bond-induced energy-transfer process. Upon the addition of Pb2+, its specific binding with the aptamer triggered the abscission of cDNA-NCQDs, accompanied by the formation of G-quadruplex on the surface of the electrode, both of which amplified the intensity of the light emission. The ECL amplification efficiency induced by the above two mechanisms (78.6%) was valuably greater than that of their sum value (69.3%). This synergistic effect resulted in high detection sensitivity of the ECL aptasensor, which allowed to thereby obtain Pb2+ measurements in the range of 1 fM - 10 nM with an ultra-low detection limit of 0.19 fM. The Pb2+-mediated synergistic signal-amplification ECL strategy can provide a new approach for integrating various amplification strategies. [Display omitted] • A Pb2+-induced synergistic signal-amplification ECL strategy was proposed. • The strategy involved simultaneous quencher releasing and G-quadruplex formation. • The synergistic effect improved the detection sensitivity of the ECL aptasensor. • The developed ECL aptasensor exhibited the superiority for Pb2+ analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dual signal amplification strategy was developed for 'on–off-on' ECL system. • Self-enhaced luminophore of Ru@SiO 2 -NGQDs provided the first 'switch on' signal. • The 'switch off' signal was obtained by the ERET between Ru@SiO 2 -NGQDs and AuNPs. • Hg2+ induced the second 'switch on' signal with amplified ECL recovery efficiency. • The method exhibited wide linear range, low LOD and good selectivity for Hg2+ assay. Divalent mercury ion (Hg2+) is widely distributed in the ecological environment and harmful to the human body and the environment. Herein, a highly sensitive and selective 'on–off-on' electrochemiluminescence (ECL) aptamer sensing method based on the dual signal amplification strategy of a self-enhanced luminophore and ECL resonance energy transfer (ECL-RET) was developed to detect Hg2+. In detail, the first 'switch-on' state was obtained by the self-enhanced luminophore of Ru(bpy) 3 2+-doped silica nanoparticle-nitrogen-doped graphene quantum dots (Ru@SiO 2 -NGQDs) modified glassy carbon electrode, which significantly amplified the ECL intensity compared with the mixture of Ru@SiO 2 and NGQDs. Later, the 'switch-off' state was induced by gold nanoparticles (AuNPs), which acted the acceptor in the ECL-RET system between AuNPs and Ru@SiO 2 -NGQDs due to their good spectral overlap. This combination of the self-enhanced luminophore and ECL-RET provided a novel dual signal amplification strategy, which led to a high signal-to-noise ratio and high analysis sensitivity. Finally, upon the addition of Hg2+, the formation of a stable T-Hg2+-T structure induced the release of AuNPs from the sensing interface and halted the ECL-RET process, resulting in ECL signal recovery (the second 'switch-on' state). For the detection of Hg2+, the proposed ECL sensor exhibited a wide linear range from 1 × 10−14 to 1 × 10−6 M and a highly sensitive detection limit of 3.0 fM. Finally, the feasibility of the developed method in water sample analysis was investigated. [ABSTRACT FROM AUTHOR]

Here, we show that nitrogen-doped carbon quantum dots (NCQDs) strongly inhibits the anodic electrochemiluminescence (ECL) signal of a tris(4,4′-dicarboxylic acid-2,2′-bipyridyl) ruthenium(II) (Ru(dcbpy) 3 2+)/tripropylamine (TPA) aqueous system. To determine the ECL-quenching mechanism, we used photoluminescence spectroscopy, UV–Visible absorption spectroscopy and dynamic simulation technology. Quenching of the ECL signal of Ru(dcbpy) 3 2+/TPA by NCQDs was predominantly attributed to the interaction between Ru(dcbpy) 3 2+ and NCQDs rather than that between TPA and NCQDs. Specifically, when Ru(dcbpy) 3 2+ and NCQDs were in aqueous solution together, the carboxyl (-COOH) groups of Ru(dcbpy) 3 2+ were in contact with oxygen- and nitrogen-containing groups on the surface of NCQDs and formed intermolecular hydrogen bonds. This process involved energy transfer from the excited-state Ru(dcbpy) 3 2+ to the intermolecular hydrogen bonds, thus resulting in a decrease in the Ru(dcbpy) 3 2+ ECL signal. On this basis, a quenching-type ECL sensor for the quantification of NCQDs was fabricated. The sensor had a wide linear range and an estimated detection limit of 0.0012 mg mL−1, as well as excellent stability and selectivity. Satisfactory recoveries of 97.0–99.5% were obtained using the ECL sensor to quantify NCQDs in tap water. NCQDs could potentially be used as a quenching probe of Ru(dcbpy) 3 2+ to construct various biosensors with widespread applications in the sensing field. • A quench-type ECL method based on intermolecular hydrogen bonds was firstly studied. • ECL quenching of Ru(dcbpy) 3 2+ by nitrogen-doped carbon quantum dots (NCQDs) was proposed. • Analysis of quenching behavior of NCQDs by sensor mechanism was developed. [ABSTRACT FROM AUTHOR]

An electrochemiluminescence (ECL) aptasensor based on poly(ethylenimine) functionalized nitrogen-doped carbon nanodots (NCDs@PEI) composite as co-reactant, and Ru(bpy) 3 2+ nanosheets (RuNSs) as luminophor was constructed for the specific analysis of bisphenol A (BPA). On account of the double improvement functions of NCDs and PEI on RuNSs, the as-developed aptasensor exhibited superior ECL properties. In order to further enhance the selectivity of the RuNSs-NCDs@PEI system for BPA detection, we innovatively introduced the BPA aptamer to construct a novel ECL aptasensor. Compared with that without aptamer and with random DNA, the constructed aptasensor performed higher specificity for BPA determination under the interference of structural analogues. The as-prepared ECL aptasensor exhibited a wide linear range of 1.0 × 10−10 - 1.0 × 10−4 mol L−1, and a relatively low detection limit of 3.3 × 10−11 mol L−1 for BPA detection with good stability and repeatability. Finally, when the ECL aptasensor made use of BPA analysis in water samples, the obtained results were confirmed by high performance liquid chromatography-ultraviolet spectrum (HPLC-UV) method, verifying its good accuracy. The novel aptasensor provided a new sensing platform for BPA in water samples. [ABSTRACT FROM AUTHOR]

• A novel self-enhanced ECL Ru(II)-complex was firstly synthesized. • Luminophor (NH 2 -Ru@SiO 2) and co-reactant (NGQDs) existed in the same nanoparticle. • An effective monitoring method for ZEN was developed by the developed aptasensor. • ZEN produced during the mildew process of corn flour was monitored. • Results exhibited superior determination and potential application in real samples. Accurate and early diagnosis of mycotoxin is particularly significant to the food and agricultural product safety. In the present work, a sensitive and effective monitoring method for zearalenone (ZEN) was exploited based on a novel self-enhanced electrochemiluminescence (ECL) aptasensor. The self-enhanced lumonophore was compounded by electrostatically combining amine-functionalized Ru(bpy) 3 2+-doped silica nanoparticles (NH 2 -Ru@SiO 2 NPs) and nitrogen doped graphene quantum dots (NGQDs) together. Since the emitter and co-reactant simultaneously existed in the same nanoparticle, shortened electron-transfer distance and decreased energy loss was obtained. Therefore, self-enhanced ECL aptasensor based on the novel complex expressed the widest linear range of 10 fg mL−1–10 ng mL−1 and the lowest detection limit of 1 fg mL−1 for ZEN detection. More importantly, ZEN produced during the mildew process of corn flour was monitored by the developed aptasensor, which exhibited superior determination and potential application in real samples. [ABSTRACT FROM AUTHOR]

Developing a simple, specific, and sensitive method for the detection of diuron is of utmost importance. Herein, a novel dual-quenching molecular imprinting polymers electrochemiluminescence (MIP-ECL) sensor, which effectively combined the "blocking effect" of MIPs and the competitive reaction between diuron and coreactant, was fabricated for high-performance analysis of diuron. Specifically, gold nanoclusters (AuNCs) were immobilized on the electrode interface to generate a robust ECL signal in the presence of triethylamine (TEA) as coreactant. The MIP was subsequently introduced employing thiophene as functional monomer and diuron as template molecule, with the cavities within the MIP utilized for diuron capture after elution. Upon the recombination of diuron, on the one hand, the electron transfer between the electrochemical oxidation product of AuNCs (AuNCs•+) and reactive radicals of TEA (TEA•) was hindered by diuron. On the other hand, a portion of TEA• was consumed by diuron to generate 3-(hydroxychlorophenyl)-1,1-dimethylurea (HCPDMU), a phenyl hydroxyl compound that could also potentially accept electron from TEA•, leading to a subsequent decline in TEA•. Both the mechanisms in turn weaken the generation of the excited-state AuNCs (AuNCs*) and reduce the ECL intensity, leading to the MIP-ECL sensor demonstrating excellent analytical performance for diuron detection. Innovatively, the interaction between diuron and TEA offered a novel research avenue for detecting diuron using the ECL system with TEA as coreactant. • It was found that diuron could quench the ECL signal of AuNCs/TEA system. • Based on the foundation, a MIP-ECL sensing platform was developed. • "Blocking effect" of MIPs and consumption of TEA by diuron were the quenched mechanisms. • The developed MIP-ECL sensor exhibited excellent performances for diuron detection. [ABSTRACT FROM AUTHOR]

Searching for a pair of electrochemiluminescence (ECL) emitters that can be simultaneously applied as energy donor-acceptor pair is very vital for ECL resonance energy transfer strategy (ECL-RET)-based ratiometric ECL aptasensors, as it can avoid the complex design caused by the addition of exogenous donor or acceptor. Herein, gold nanoclusters (AuNCs) with aggregation-induced emission property and amino-terminated perylene derivative (PTC-NH 2) with a broad absorption range were firstly combined to generate the anodic and cathodic ECL signals, respectively. Importantly, they were also operated as a novel ECL-RET donor-acceptor pair due to their favorable spectral overlap. On this basis, a potential-resolved ratiometric ECL aptasensor was established to detect lead ions (Pb2+). Specifically, the energy of AuNCs was absorbed by PTC-NH 2 in the absence of Pb2+, leading to a decrease of the anodic ECL signal and the appearance of the cathodic ECL signal. Upon the addition of Pb2+, the ECL-RET process was impeded, and the ECL signals were reversed. By measuring the ratio of AuNCs and PTC-NH 2 ECL intensities, the developed ratiometric ECL aptasensor displayed a low detection limit of 0.05 pM with excellent selectivity and satisfactory stability. Finally, the proposed aptasensor presented favorable feasibility for Pb2+ assays in soil samples. • A ratiometric ECL aptasensor based on RET between AuNCs and PTC-NH 2 was designed. • AuNCs and PTC-NH 2 acted as both emitters and RET donor-acceptor pair. • The aptasensor showed excellent analytical performances for Pb2+ analysis. [ABSTRACT FROM AUTHOR]

• An on-off-on ECL aptasensor was developed based on dual signal amplification strategy. • Aggregation-induced emission behavior of AuNCs provided the first signal-on state. • The signal-off state was realized by resonance energy transfer between RhB and AuNCs. • The Pb2+-induced second "signal-on" state was obtained by blocking RET process. • The proposed aptasensor showed excellent analytical performance for Pb2+ analysis. In the present work, based on dual signal amplification strategy of aggregation-induced emission (AIE) and resonance energy transfer (RET), a highly sensitive and selective "on-off-on" output model electrochemiluminescence (ECL) aptasensor for Pb2+ detection was constructed. In this approach, the first "signal-on" with a high and stable ECL signal was obtained by gold nanoclusters (AuNCs)-modified glassy carbon electrode surface with triethylamine as co-reactant. The AIE behaviour of AuNCs amplified ECL emission compared with AuNCs in solution. Later, the "signal-off" was activated by rhodamine B (RhB) quenched the AuNCs signal due to good spectral overlap between ultraviolet-visible absorption peak of RhB and ECL spectrum of AuNCs. The combination of dual signal amplification strategy provided a high signal to background ratio, leading to the improved sensitivity of the aptasensor. In the presence of Pb2+, its specific binding to the aptamer induced the departure of RhB from the sensing interface, which resulted in the favourable recovery of ECL signal (Second "signal-off"). Therefore, the proposed ECL aptasensor exhibited a wide detection linear range from 1.0 × 10−10 to 1.0 × 10−4 M. Prospectively, the development dual signal amplification strategy could provide a novel sensing strategy for Pb2+ detection. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] A sensitive ECL sensor was developed by combining Ru(bpy)3 2+-doped silica (Ru(bpy)3 2+@SiO2) nanoparticles with graphene. [•] The proposed sensor exhibited high sensitivity (∼10−13 M) and wide linear range for melamine. [•] This method was successfully applied to the detection of melamine in milk. [Copyright &y& Elsevier]

Aflatoxin contamination causes tremendous economic losses and seriously threatens human health due to its prevalence in agricultural products and foods coupled with the severe toxicity of aflatoxins. Thus, sensitive, reliable, and rapid methods for aflatoxin analysis are urgently required. In recent years, electrochemical biosensors have emerged as a suitable alternative to gold standard methods that rely on sophisticated instruments (e.g. HPLC-MS). This review aims to describe recent advances (2016–2019) in electrochemical biosensors for aflatoxins detection in novel sensing strategies, recognition reporters, and integrated platforms. Particular emphasis is placed on the utilization of novel sensing strategies including dual-mode detection and ratiometric sensing in the fabrication of biosensors based on electrochemistry, photoelectrochemistry, and electrochemiluminescence. Meanwhile, a comprehensive discussion is provided on the challenges and perspectives related to electrochemical biosensing of aflatoxins. • This review aims to provide the recent advances of electrochemical biosensors for aflatoxins. • Particular emphasis is given to the ratiometric electrochemical biosensing and dual-mode detection. • Challenges and perspectives related to electrochemical biosensing of aflatoxin are discussed. [ABSTRACT FROM AUTHOR]

• An innovative self-enhanced luminophore was composed by electrostatic interaction. • Luminophor (NH 2 -RuDS) and co-reactant (NGQDs) can combine in one nanoparticle. • A sensitive ECL sensor was successfully constructed for carbaryl quantification. • The novel luminophore with great performance has great potential in bioanalysis. Self-enhanced electrochemiluminescence (ECL) technology has raised special concern on analytical performance owing to its accurate measurement. In this study, an innovative self-enhanced luminophore was synthesized utilizing nitrogen doped graphene quantum dots (NGQDs) as co-reactant of Ru(bpy) 3 2+-doped silica nanoparticles (RuDS NPs). Because both RuDS NPs and NGQDs exhibited negative charge, the RuDS NPs were firstly modified with amino groups to produce positively charged NH 2 -RuDS NPs, which can be further successfully combined with negatively charged NGQDs via electrostatic interaction. Compared with the mixture of NH 2 -RuDS NPs and NGQDs, the NH 2 -RuDS@NGQDs luminophore expressed superior ECL performance due to its short electron transfer distance and low energy loss. Based on the quenching effect between the excited state of NH 2 -RuDS@NGQDs luminophore and the oxidation form of carbaryl, a sensitive ECL sensor was successfully constructed for carbaryl quantification. The proposed self-enhanced ECL sensor exhibited a relatively wider linear range of 1.0 × 10−13 - 1.0 × 10-4 g mL-1 and a lower detection limit of 2.2 × 10-15 g mL-1 in compassion with most reported methods. Therefore, the innovative self-enhanced NH 2 -RuDS@NGQDs luminophore with excellent performance may expand great potential in bioanalysis. [ABSTRACT FROM AUTHOR]