Amine-Rich Nitrogen-Doped Carbon Nanodots as a Platform for Self-Enhancing Electrochemiluminescence

Size-selected and surface-passivated CsPbBr3 perovskite nanocrystals for self-enhanced electrochemiluminescence in aqueous media

In this work, CsPbBr3 perovskite nanocrystals (NCs) synthesized via a ligand-assisted reprecipitation method (LCPB) were discovered to emit self-enhanced electrochemiluminescence (ECL) with the surface oleylamine as both a coreactant and a stabilizer. Solvent regulation and tri-n-octylphosphine post-treatment were manipulated for size-selected and surface-passivated LCPBs, which showed remarkable aqueous ECL performance with respect to efficiency and stability. Furthermore, thanks to the self-enhancement mode with a shorter charge transfer pathway and less energy loss, the ECL efficiency obtained for these as-synthesized LCPBs in aqueous solution without any additional coreactant was up to 57.08% using the Ru(bpy)32+-tripropylamine system as the standard. As a proof-of-concept, the products were successfully employed for the bioanalyses of hydrogen peroxide, ascorbic acid, and cancer cells based on inhibition, coreaction, and impedance detection principles, respectively. More importantly, the basic properties of LCPBs in aqueous media including surface chemistry, charge transfer process, and ECL mechanism were studied systematically. Such efforts are aimed at perfecting the fundamental research of all-inorganic perovskite NCs and opening an avenue for the design of highly crystalline and luminescent perovskites as advanced ECL emitters for applications in the ECL domain.

Ultrasensitive self-enhanced electrochemiluminescence sensor based on novel PAN@Ru@PEI@Nafion nanofiber mat

A novel self-enhanced electrochemiluminescence nanofiber mat was for the first time prepared by one-step electrospinning a mixture of polyacrylonitrile, Ru(bpy)₃²⁺, poly(ethylenimine) and Nafion.

Acridine orange as a coreactant for efficient electrogenerated chemiluminescence of tris(2,2′-bipyridine)ruthenium(ii) and its use in selective and sensitive detection of thiourea

We introduced a novel coreactant for efficient anodic electrochemiluminescence of Ru(bpy)₃²⁺ and applied it for the sensitive detection of thiourea for the first time.

Gold nanoparticles decorated carbon nitride nanosheets as a coreactant regulate the conversion of the dual-potential electrochemiluminescence of Ru(bpy)32+ for Hg2+ detection

Dual-potential electrochemiluminescence of Ru(bpy)₃²⁺ for Hg²⁺ assay using Au–g-C₃N₄ NSs as on-electrode coreactant.

A dual-signal output ratiometric electrochemiluminescent sensor for NADH detection

Ratiometric electrochemiluminescence (ECL) has attracted great attention in the field of electrochemical analysis. In this study, a dual-signal-output ratiometric ECL sensor was developed for the detection of nicotinamide adenine dinucleotide (NADH). Nitrogen-doped graphene quantum dots (NGQDs) exhibit double ECL signal output capability, without the requirement of additional coreactants. NADH can amplify the anodic ECL response of NGQDs, while it can diminish the cathodic ECL response of NGQDs. Based on the principle between relative enhancing ECL intensity ratio and NADH concentrations, the constructed ratiometric ECL sensor was applied to NADH assays, with a wide concentration range of 10-400 μM and a low limit of detection (LOD) of 2.5 μM (S/N = 3). Furthermore, the proposed method was applied for the determination of spiked NADH, which was proved to be feasible in the biological sample matrix. The proposed strategy of modulating multiple-ECL signals of the single NGQD emitter not only provides a new ECL system for the accurate detection of NADH but also broadens the design pathway for ratiometric sensing fabrication.

Use of Nitrogen-Doped Carbon Nanodots for the Photocatalytic Fluoroalkylation of Organic Compounds

The use of amine-rich N-doped carbon nanodots (NCNDs) for the photochemical radical perfluoroalkylation of organic compounds is reported. This operationally simple approach occurs under mild conditions producing valuable new C-C bonds. The chemistry is driven by the ability of NCNDs to directly reach an electronically excited state upon light absorption, thereby successively triggering the formation of reactive radical species from simple perfluoroalkyl iodides. Preliminary mechanistic studies are also reported.

Carbon dots: advances in nanocarbon applications

Carbon dots (C-Dots), defined by characteristic sizes of <10 nm, have become a rising star in carbon nanomaterials. C-Dots possess many unique physiochemical and photochemical properties which make them a promising platform for imaging, environmental, catalytic, biological and energy-related applications. To date, C-Dots have been investigated extensively, and their related applications have developed rapidly. However, quantitative understanding of the physiochemical properties of C-Dots still remains a difficult challenge because of their complex structures. Here, we will highlight the recent progress in the practical applications of C-Dots, with particular attention to the research in light-emitting devices, bioimaging and biodetection, catalysis, functional materials, and agriculture.

A conceptual framework for the development of iridium(iii) complex-based electrogenerated chemiluminescence labels

Translation of the highly promising electrogenerated chemiluminescence (ECL) properties of Ir(iii) complexes (with tri-n-propylamine (TPrA) as a co-reactant) into a new generation of ECL labels for ligand binding assays necessitates the introduction of functionality suitable for bioconjugation. Modification of the ligands, however, can affect not only the photophysical and electrochemical properties of the complex, but also the reaction pathways available to generate light. Through a combined theoretical and experimental study, we reveal the limitations of conventional approaches to the design of electrochemiluminophores and introduce a new class of ECL label, [Ir(C^N)2(pt-TOxT-Sq)]+ (where C^N is a range of possible cyclometalating ligands, and pt-TOxT-Sq is a pyridyltriazole ligand with trioxatridecane chain and squarate amide ethyl ester), which outperformed commercial Ir(iii) complex labels in two commonly used assay formats. Predicted limits on the redox potentials and emission wavelengths of Ir(iii) complexes capable of generating ECL via the dominant pathway applicable in microbead supported ECL assays were experimentally verified by measuring the ECL intensities of the parent luminophores at different applied potentials, and comparing the ECL responses for the corresponding labels under assay conditions. This study provides a framework to tailor ECL labels for specific assay conditions and a fundamental understanding of the ECL pathways that will underpin exploration of new luminophores and co-reactants.

Highly Luminescent and Self-Enhanced Electrochemiluminescence of Tris(bipyridine) Ruthenium(II) Nanohybrid and Its Sensing Application for Label-Free Detection of MicroRNA

Inspired by the coreactive activity of carbon nanodots (CDs) and branched polyethylenimine (BPEI) toward electrochemiluminescence (ECL) of Ru(bpy)₃²⁺, a highly luminescent and self-enhanced ECL nanohybrid (Ru-BCDs) was synthesized through covalently linking BPEI-coated carbon dots (BCDs) with Tris (4,4'-dicarboxylic acid-2,2'-bipyridyl) ruthenium(II) dichloride (Ru(dcbpy)₃²⁺). The composition and morphological characterization demonstrated that the spherical Ru-BCDs particles with 12.1 ± 1.4 nm diameter were obtained. The enhanced ECL property of Ru-BCDs was proved to originate from the dual coreactive contribution of BPEI and CDs as coreactants as well as the intramolecular electron transfer process, which could shorten the electron transfer path and minimize energy loss. A carbon nitride nanosheet (CNN) was utilized to stabilize the Ru-BCDs-modified glassy carbon electrode, which greatly improved the stability of solid-state ECL. By utilizing the affinity discrepancy of the CNN to single-stranded and double-stranded nucleic acids, a label-free and signal-on ECL biosensor was constructed for the determination of microRNA-133a (miR-133a), a potential biomarker of acute myocardial infarction. The designed biosensor exhibited good performance of miR-133a detection with a detection limit of 60 fM and could be used for the detection of real human serum with satisfactory results. The self-enhanced ECL nanohybrid with distinguished ECL efficiency holds a promising prospect in biosensing and bioimaging applications.

Au-Luminol-decorated porous carbon nanospheres for the electrochemiluminescence biosensing of MUC1

Electrochemiluminescence (ECL) nanomaterials are usually deposited compactly on the surface of electrodes, which may cause poor mass transfer of reactants, thereby resulting in low ECL efficiency. In this work, we developed a novel kind of luminescent material denoted as C-Au-luminol nanospheres (C-Au-Lum NSs) by high dispersion of luminophores on porous carbon nanospheres (PCNSs). C-Au-Lum NSs were facilely prepared by the in situ reduction of chloroauric acid with the luminescent reagent luminol (Lum) on the nano-pores of PCNSs. Plenty of luminescent Au-Lum NPs were dispersedly concentrated inside the numerous pores and hollow interiors of PCNSs, effectively increasing the mass transfer of reagents and accelerating the electron transport inside the porous nanospheres. This greatly improved the availability of luminophores and endowed C-Au-Lum NSs with excellent ECL emission. After further integrating with enzymatic circulation and strand displacement, an ultrasensitive ECL biosensor was achieved for the ultrasensitive detection of an important tumor biomarker, mucin1. The logarithmically linear range from 0.1 pg mL-1 to 1 ng mL-1 with the detection limit of 47.6 fg mL-1 (S/N = 3) was achieved, demonstrating the superior performance of C-Au-Lum NSs. This work would provide new ideas for the construction of high-performance ECL sensing platforms for diverse applications.

Preparation, functionalization and characterization of engineered carbon nanodots

Carbon-based dots (CDs) and their functionalized (nano)composites have recently attracted attention due to their seemingly easy preparation and numerous potential applications, ranging from those in the biomedical field (i.e., imaging and drug delivery) to those in (opto)electronics (i.e., solar cells and LEDs). This protocol details step-by-step procedures for synthesis, purification, functionalization and characterization of nitrogen-doped carbon nanodots (NCNDs), which we have been preparing for the past few years. First, we describe the bottom-up synthesis of NCNDs, starting with the use of molecular precursors (arginine (Arg) and ethylenediamine (EDA)) and making use of microwave-assisted hydrothermal heating. We also provide guidelines for the purification of these materials, through either dialysis or low-pressure size-exclusion chromatography (SEC). Second, we outline post-functionalization procedures for the surface modification of NCNDs, such as alkylation and amidation reactions. Third, we provide instructions for the preparation of NCNDs with different properties, such as color emission, electrochemistry and chirality. Given the fast evolution of preparations and applications of CDs, issues that might arise from artifacts, errors and impurities should be avoided. In this context, the present protocol aims to provide details and guidelines for the synthesis of high-quality nanomaterials with high reproducibility, for various applications. Furthermore, specific needs might require the CDs to be prepared by different synthetic procedures and/or from different molecular precursors, but such CDs can still benefit from the purification and characterization procedures outlined in this protocol. The sample preparation takes various time frames, ranging from 4 to 18 d, depending on the adopted synthesis and purification steps.

Design, Synthesis, and Functionalization Strategies of Tailored Carbon Nanodots

Over the past decades, considerable efforts have been devoted to synthesizing nanostructured materials with specific properties that ultimately shape their function. In the carbon nanotechnology era, for nanomaterials such as fullerenes, carbon nanotubes, and graphene, the main focus has been on the organic functionalization of these nanostructures, in order to tailor their processability and applicability. Carbon-based dots, quasi-spherical nanoparticles with a shape under 10 nm, have popped up into this context especially due to their versatile synthesis and intriguing properties, mainly their fluorescence emission. Even though they were discovered through the top-down route of cutting large carbon nanostructures, in recent years the ease and flexibility of the bottom-up synthesis have allowed this carbon-based class of nanomaterials to advance at a striking pace. However, the fast speed of research and publication rate have caused a few issues that affect their classification, purity criteria, and fluorescence mechanisms. As these are being progressively addressed, the true potential and applicability of this nanomaterial has started to unravel. In this Ariticle, we describe our efforts toward the synthesis, purification, characterization, and applications of carbon nanodots. Special attention was dedicated to designing and customizing the optoelectronic properties of these nanomaterials, as well as their applications in hybrid and composite systems. Our approach is centered on a bottom-up, microwave-assisted hydrothermal synthesis. We have successfully exploited a multicomponent synthetic approach, using arginine and ethylenediamine as starting materials. By controlling the reaction conditions, in just 3 min, blue-emitting carbon nanodots become accessible. We have improved this approach by designing and tuning the emissive, electrochemical, and chiroptical properties of these nanoforms. On the other hand, we have used postfunctionalization reactions as a tool for conjugation with suitable partners and for further tuning the surface chemistry. The combination of these two approaches has produced a number of carbon nanodots that can be investigated in fields ranging from biology to materials chemistry and in applications spanning from nanomedicine to energy conversion.

Triple-helix molecular switch-based versatile "off-on" electrochemiluminescence and fluorescence biosensing platform for ultrasensitive detection of lipopolysaccharide by multiple-amplification strategy

Herein, a novel biosensing platform for versatile electrochemiluminescence (ECL) "off" and fluorescence (FL) "on" detection of lipopolysaccharide (LPS) with multiple-amplification strategy is proposed. The specific recognition of target to aptamer on the magnetic beads (MB) firstly released abundant DNA sequences of three kinds. The sequences hybridized with multifunctional molecular beacon (MMB) and initiated numerous bidirectional polymerization and shearing reactions, generating a large number of DNA fragments (a1) by multiple cycling amplification. Then a1 was introduced to the triple-helix sensing system, opening the triple-helix structure. In ECL system, the G-rich chains S2 were exposed to form G-quadruplex-hemin complex in the presence of hemin, which could efficiently quench ECL for "off" detection of LPS. In FL system, the fluorophore FAM and quencher BHQ on S1 chain were separated with opening of triple-helix structure, achieving fluorescence "on" signal for LPS assay. So the versatile platform can achieve greatly amplified ECL and FL signal changes for sensitive assay of LPS, showing wide linear ranges (0.1 fg/mL-0.1 ng/mL by ECL and 10 fg/mL^-1-1 μg/mL by FL) and low detection limits (0.012 fg/mL by ECL and 1.269 fg/mL by FL). Therefore, the present ECL "Off" and FL "On" dual-signal detection patterns for LPS displayed many advantages over other reported methods, which provided an outlook for future applications in clinical diagnosis.

Ultrasensitive Immunosensor for Cardiac Troponin I Detection Based on the Electrochemiluminescence of 2D Ru-MOF Nanosheets

Electrochemiluminescence (ECL)-functionalized metal-organic frameworks (MOFs) have attracted increasing attention in biosensing in virtue of their diverse and tunable optical properties. A famous ECL luminophore, carboxyl-rich tris(4,4'-dicarboxylic acid-2,2'-bipyridyl) ruthenium(II) (Ru(dcbpy)₃²⁺), possesses the characteristics of good water solubility and excellent ECL performance and also has the potential to be the organic ligand of metal-organic frameworks. Herein, functionalized MOF nanosheets (RuMOFNSs) containing plenty of Ru(dcbpy)₃²⁺ in the frameworks were synthesized in aqueous solution by a simple one-pot method. In this protocol, Ru(dcbpy)₃²⁺ acted as organic ligand to coordinate with Zn²⁺ originated from Zn(NO₃)₂, and polyvinylpyrrolidone (PVP) was used as structure-directing agent to control the formation of sheetlike structure. For practical application, a "signal-on" ECL immunosensor was designed for cardiac troponin I (cTnI) detection by employing RuMOFNSs as ECL probe. The immunosensor exhibited high sensitivity and excellent selectivity for cTnI detection in the range from 1 fg/mL to 10 ng/mL with a detection limit as low as 0.48 fg/mL. Finally, the biosensor was successfully applied for the detection of cTnI in human serum sample with satisfactory results, demonstrating its potential application in bioanalysis and clinical diagnosis.

Construction of a flexible electrochemiluminescence platform for sweat detection

Flexible and wearable chemical sensors show great capability and potential in retrieving physiologically related chemical or biochemical information from elastic and curvilinear living bodies. However, so far, no flexible electrochemiluminescence (ECL) device has been reported, though ECL measurements have been extensively investigated and widely applied in many fields. Herein, we for the first time designed and fabricated a flexible ECL sensor by immobilizing highly luminescent nanospheres on Au nanotube (Au NT) networks, and subsequently coating an elastic molecularly imprinted polymer (MIP) thereon. The as-prepared flexible ECL platform displayed successive and desirable mechanical compliance while generating a very stable ECL signal during deformation, facilitating highly selective detection of physiologically relevant chemicals from bodies. On-body wearable sampling and subsequent detection of lactate and urea from sweat showed the ECL performance of this sensor displaying desirable fidelity, reusability and high stability against disturbance. This work successfully incorporated the ECL sensing model into a flexible and wearable device, therefore providing a promising new path for non-invasively monitoring the products of metabolism for health care and biomedical investigations.

Monitoring zearalenone in corn flour utilizing novel self-enhanced electrochemiluminescence aptasensor based on NGQDs-NH2-Ru@SiO2 luminophore

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)₃²⁺-doped silica nanoparticles (NH₂-Ru@SiO₂ 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.

Carbon nanodot-based heterostructures for improving the charge separation and the photocurrent generation

The possibility to employ carbon nanodots (CNDs) in solar devices was exploited by combining them with a fulleropyrrolidine derivative (FP2). The interaction between the two species was promoted by the presence of opposite electrostatic charges on CNDs (negatively charged) and FP2 (positively charged). The supramolecular dyad CNDs/FP2 generation was induced at the air/water interface of a Langmuir trough: water soluble CNDs were dissolved in the subphase and FP2 chloroform solution was spread on the subphase; the electrostatic interaction promoted the formation of the supramolecular adduct FP2/CNDs, which was then transferred onto solid substrates. Photo-induced charge transfer was promoted in the FP2/CNDs dyad and we demonstrated that the presence of CNDs increased the short-circuit current density, under light illumination, of a porphyrin-FP2/CNDs thin film by about 300% when compared with a more traditional porphyrin-FP2 solar device.

Nitrogen-doped graphene quantum dots coated with gold nanoparticles for electrochemiluminescent glucose detection using enzymatically generated hydrogen peroxide as a quencher

Nitrogen-doped graphene quantum dots (N-GQDs) were prepared from dicyandiamide and then used as both an electrochemiluminescence (ECL) emitter and a reductant to produce gold nanoparticles (Au-N-GQDs) on their surface without using any reagent. In order to avoid resonance energy transfer, the Au-N-GQDs were stabilized with chitosan. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV-vis spectroscopy (UV-vis) and ECL methods were used to characterize the nanocomposite. The materials was placed on a glassy carbon electrode (GCE), and the ECL signals are found to be strongly quenched by hydrogen peroxide that is enzymatically produced by oxidation of glucose. With the applied typical potential of -1.7 V, the ECL of the Au-N-GQDs modified GCE decreases linearly in the 10 nM to 5.0 μM glucose concentration range, and the lower detection limit is 3.3 nM. The influence of H₂O₂ to the signal has been discussed and a possible mechanism has been presented. Graphical abstract Schematic presentation of the reduction of gold nanoparticles with nitrogen-droped graphene quantum dots (N-GQDs) to form Au-N-GQDs. They were used to detect glucose by electrochemiluminescence through a signal off strategy.

Design and fabrication of carbon dots for energy conversion and storage

This review covers the recent advances of carbon dots for versatile energy-oriented applications.

BSA stabilized tetraphenylethylene nanocrystals as aggregation-induced enhanced electrochemiluminescence emitters for ultrasensitive microRNA assay

An ultrasensitive ECL biosensing platform was constructed based on BSA stabilized tetraphenylethylene nanocrystals to achieve microRNA detection in cancer cells.

Nitrogen-doped carbon dots derived from electrospun carbon nanofibers for Cu(ii) ion sensing

Nitrogen-doped carbon dots were synthesized via the chemical breakdown of electrospun polyacrylonitrile-based carbon nanofibers and employed as a fluorescent sensing platform.

Bright Yellow Fluorescent Carbon Dots as a Multifunctional Sensing Platform for the Label-Free Detection of Fluoroquinolones and Histidine

Owing to their diverse properties, fluorescent carbon dots (CDs) have attracted more attention and present enormous potential in development of sensors, bioimaging, drug delivery, microfluidics, photodynamic therapy, light emitting diode, and so forth. Herein, a multifunctional sensing platform based on bright yellow fluorescent CDs (Y-CDs) was designed for the label-free detection of fluoroquinolones (FQs) and histidine (His). The Y-CDs with superior optical and biological merits including high chemical stability, good biocompatibility, and low cytotoxicity were simply synthesized via one-step hydrothermal treatment of o-phenylenediamine ( o-PD) and 4-aminobutyric acid (GABA). The Y-CDs can be utilized to directly monitor the amount of FQs based on fluorescence static quenching owing to the specific interaction between FQs and Y-CDs. Then, the fluorescence of this system can be effectively recovered upon addition of His. The multifunctional sensing platform exhibited high sensitivity and selectivity toward three kinds of FQs and His with low detection limits of 17-67 and 35 nM, respectively. Benefiting from these outstanding characters, the Y-CDs were successfully employed for trace detection of FQs in real samples such as antibiotic tablets and milk products. Furthermore, the probe was also extended to cellular imaging. All of the above prove that this multifunctional sensing platform presents great prospect in multiple applications such as biosensing, biomedicine, disease diagnosis, and environmental monitoring.

Nitrogen-doped carbon nanodots for bioimaging and delivery of paclitaxel

Carbon nanodots (CNDs) hold great potential in imaging and drug delivery applications. In this study, nitrogen-doped CNDs (NCNDs) were coupled to the anticancer agent paclitaxel (PTX) through a labile ester bond. NCNDs showed excellent cell viability and endowed the NCND-PTX conjugate with good water solubility. The hybrid integrates the optical properties of the nanodots with the anticancer function of the drug into a single unit. Cytotoxicity was evaluated in breast, cervix, lung, and prostate cancer cell lines by the MTT assay while the cellular uptake was monitored using confocal microscopy. NCND-PTX induced apoptosis in cancer cells exhibiting slightly better anticancer activity compared to the drug alone. Moreover, the course of the NCND-PTX interaction with cancer cells was monitored using an xCELLigence system. The NCND-based conjugate represents a promising platform for bioimaging and drug delivery.

Design principles of chiral carbon nanodots help convey chirality from molecular to nanoscale level

The chirality of (nano)structures is paramount in many phenomena, including biological processes, self-assembly, enantioselective reactions, and light or electron spin polarization. In the quest for new chiral materials, metallo-organic hybrids have been attractive candidates for exploiting the aforementioned scientific fields. Here, we show that chiral carbon nanoparticles, called carbon nanodots, can be readily prepared using hydrothermal microwave-assisted synthesis and easily purified. These particles, with a mean particle size around 3 nm, are highly soluble in water and display mirror-image profile both in the UV–Vis and in the infrared regions, as detected by electronic and vibrational circular dichroism, respectively. Finally, the nanoparticles are used as templates for the formation of chiral supramolecular porphyrin assemblies, showing that it is possible to use and transfer the chiral information. This simple (and effective) methodology opens up exciting opportunities for developing a variety of chiral composite materials and applications.

A promising and efficient route to chiral materials involves the transfer of chirality across length scales. Here, the authors use chiral molecular precursors to synthesize chiral carbon nanodots, which in turn can template the formation of chiral supramolecular assemblies.

A single-electrode electrochemical system for multiplex electrochemiluminescence analysis based on a resistance induced potential difference

A single-electrode electrochemical system uses only one electrode for multiplex experiments, and is a highly cheap platform for high throughput analysis.

Developing low-cost and simple electrochemical systems is becoming increasingly important but still challenged for multiplex experiments. Here we report a single-electrode electrochemical system (SEES) using only one electrode not only for a single experiment but also for multiplex experiments based on a resistance induced potential difference. SEESs for a single experiment and multiplex experiments are fabricated by attaching a self-adhesive label with a hole and multiple holes onto an ITO electrode, respectively. This enables multiplex electrochemiluminescence analysis with high sensitivity at a very low safe voltage using a smartphone as a detector. For the multiplex analysis, the SEES using a single electrode is much simpler, cheaper and more user-friendly than conventional electrochemical systems and bipolar electrochemical systems using electrode arrays. Moreover, SEESs are free from the electrochemiluminescent background problem from driving electrodes in bipolar electrochemical systems. Since numerous electrodes and cover materials can be used to fabricate SEESs readily and electrochemistry is being extensively used, SEESs are very promising for broad applications, such as drug screening and high throughput analysis.

Strong Electrochemiluminescence from MOF Accelerator Enriched Quantum Dots for Enhanced Sensing of Trace cTnI

The development of a sensitive and practical electrochemiluminescence (ECL) bioassay relies on the use of ECL signal tags whose signal intensity is high and stable. In this work, strong ECL emission was achieved from metal organic framework (MOF) accelerator enriched quantum dots (CdTe), which were applied as an efficient ECL signal tag for trace biomarker detection. It is particularly noteworthy that a novel mechanism to drastically enhance the ECL intensity of CdTe is established because isoreticular metal organic framework-3 (IRMOF-3) with 2-amino terephthalic acid (2-NH₂-BDC) as the organic ligand not only allows for loading a large amount of CdTe via the encapsulating effect and internal/external decoration but also functions as a novel coreactant accelerator for promoting the conversion of coreactant S₂O₈^2- into the sulfate radical anion (SO₄^•-), further boosting the ECL emission of CdTe. On the basis of the simple sandwich immunoreaction approach, cardiac troponin-I antigen (cTnI), a kind of biomarker related with myocardial infarction, was chosen as a detection model using an IRMOF-3-enriched CdTe labeled antibody as the signal probe. This immunosensor demonstrated desirable assay performance for cTnI with a wide response range from 1.1 fg mL^-1 to 11 ng mL^-1 and a very low detection limit (0.46 fg mL^-1). This suggested that the IRMOF-3-enriched CdTe nanocomposite strategy can integrate the coreactant accelerator and luminophore to significantly enhance the ECL intensity and stability, providing a direction for promising ECL tag preparation with broad applications.

Nitrogen-Doped Carbon Nanodots-Ionogels: Preparation, Characterization, and Radical Scavenging Activity

Hybrid diimidazolium-based ionogels were obtained by dispersing nitrogen-doped carbon nanodots (NCNDs) in ionic liquid (IL) solutions and by using dicationic organic salts as gelators. The properties of the NCND-ionogels were studied in terms of thermal stability, mechanical strength, morphology, rheological, and microscopic analyses. Insights into the formation of the hybrid soft material were attained from kinetics of sol-gel phase transition and from estimating the size of the aggregates, obtained from opacity and resonance light-scattering measurements. We demonstrate that, on one hand, NCNDs were able to favor the gel formation both in the presence of gelating and nongelating ILs. On the other hand, the gelatinous matrix retains and, in some cases, improves the properties of NCNDs. The NCND-ionogels showed the typical fluorescence emission of the carbon dots and a notable antiradical activity, with higher efficiency as compared to the single components. The presented hybrid materials hold great promise for topical applications in antioxidant fields.