Enhanced Electrochemiluminescence Emission Research Articles

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.

Effect of surface ligand density on near-infrared electrochemiluminescence of glutathione-stabilized Au nanoclusters

Here, we report the crucial role of surface ligand density in electrochemiluminescence (ECL) of water-soluble Au NCs stabilized with glutathione ligands. The Au NCs, having four distinct surface ligand densities, displayed unique ECL features that were dependent on the surface ligand density of the NCs, similar to their fluorescence properties. The Au NCs displayed dual-wavelength ECL emissions at ∼620 nm and ∼820 nm. The ECL properties were significantly affected by the surface ligand density of the NCs, with lower densities resulting in enhanced ECL emission, particularly in the near-infrared region. This enhancement surpassed the near-infrared ECL emissions observed in other known ECL-active Au NCs, resulting in approximately a 9-fold improvement compared to well-established Au NCs stabilized with bovine serum albumin (BSA). In addition, the dual-emission features of the Au NCs stabilized with glutathione were attributed to the presence of two Au-S emission motifs related to different Au-S bonding environments resulting from varied surface ligand densities. These findings revealed the critical role of the surface ligand density in modulating not only the fluorescence of the Au NCs but also the ECL of NCs.

Single-atom boosted electrochemiluminescence via phosphorus doping of Fe-N/P-C catalysts.

Single-atom catalyst (SAC), one of the most attractive catalysts in the field of energy conversion and storage, was proven as efficient accelerator for luminol-dissolved oxygen electrochemiluminescence (ECL) via the catalysis of oxygen reduction reaction (ORR). In this work, we synthesized heteroatom doping SACs of Fe-N/P-C for the catalysis of cathodic luminol ECL. The doping of P could lower the reaction energy barrier of the OH* reduction, and promote catalytic efficiency toward ORR. The formation of reactive oxygen species (ROS) during ORR triggered cathodic luminol ECL. Greatly enhanced ECL emission catalyzed by SACs proved that Fe-N/P-C exhibited higher catalytic activity to ORR compared with Fe-N-C. Since the system was highly dependent on oxygen, an ultra-sensitive detection of a typical antioxidant, ascorbic acid, was achieved with detection limit of 0.03nM. This study provides possibility to greatly enhance the performance of ECL platform through rational tailoring of SACs via heteroatom doping.

Aggregation-Induced Enhancement Electrochemiluminescence of Ag Nanoribbons as a Signal Probe for Ultrasensitive Detection of the Halogenase Gene Segment from Aspergillus Ochratoxin.

Here, an electrochemiluminescence (ECL) biosensor was developed based on aggregation-induced enhancement ECL of Ag nanoribbons (Ag NRs) as a signal probe and the mismatched bases-fueled DNA walker as the amplification strategy for ultrasensitive detection of the halogenase gene segment (target) from aspergillus ochratoxin to evaluate fungi capable of producing ochratoxin in dairy products. Compared with the existing agminated NCs, the Ag NRs displayed dramatically enhanced ECL emission due to effective electron transfer and less energy dissipation of excited-state Ag NRs based on the metallophilic interaction of Ag(I)-Ag(I). Impressively, the target was conversed mismatched bases-DNA walker to trigger a significant ECL response through toehold-mediated strand displacement amplification. Thus, the strategy realized trace analysis of the halogenase gene segment with a detection limit of 45 aM, which ushered a new detection method for toxin determination in the previous stage of toxin biosynthesis to protect people from toxic damage.

Highly Efficient Wavelength-Resolved Electrochemiluminescence of Carbon Nitride Films for Ultrasensitive Multiplex MicroRNA Detection.

The development of electrochemiluminescence (ECL) emitters of different colors with high ECL efficiency (ΦECL) is appealing yet challenging for ultrasensitive multiplexed bioassays. Herein, we report the synthesis of highly efficient polymeric carbon nitride (CN) films with fine-tuned ECL emission from blue to green (410, 450, 470, and 525 nm) using the precursor crystallization method. More importantly, naked eye-observable and significantly enhanced ECL emission was achieved, and the cathodic ΦECL values were ca. 112, 394, 353, and 251 times those of the aqueous Ru(bpy)3Cl2/K2S2O8 reference. Mechanism studies showed that the density of surface-trapped electrons, the associated nonradiative decay pathways, and electron-hole recombination kinetics were crucial factors for the high ΦECL of CN. Based on high ΦECL and different colors of ECL emission, the wavelength-resolved multiplexing ECL biosensor was constructed to simultaneously detect miRNA-21 and miRNA-141 with superior low detection limits of 0.13 fM and 25.17 aM, respectively. This work provides a facile method to synthesize wavelength-resolved ECL emitters based on metal-free CN polymers with high ΦECL for multiplexed bioassays.

Introducing AgNPs-VB2 composites as the dual signal quenching of CeO2–AuNPs-g-CNQDs hybrids for ultrasensitive “on-off” electrochemiluminescence immunosensing of prostate specific antigen

An ultrasensitive resonance energy transfer based “on-off” switch electrochemiluminescence (ECL) immunosensing strategy was proposed and applied for prostate specific antigen (PSA) detection. In detail, self-enhancing nanohybrids of nano-CeO2 and AuNPs decorated graphitic carbon nitride quantum dots (CeO2–AuNPs–g-CNQDs) were synthesized, which produced high ECL emission with coreactant K2S2O8 for “switch-on” state. Noticeably, due to the reversible Ce3+↔ Ce4+ reaction, nano-CeO2 could serve as highly-efficient coreaction accelerator and induce the decomposition of S2O82− into SO4• -, which endowed the g-CNQDs/K2S2O8 system with enhanced ECL emission. Moreover, AuNPs acted crucial role in promoting the electronic transmission rate and providing sites to immobilize the biomolecules. On the other hand, the AgNPs-VB2 nanocomposites were used as dual labels to quench the ECL signal of g-CNQDs-K2S2O8 system via ECL-RET, leading to the decreased ECL for “switch-off” state. On the basis of sandwich-typed immunosensing strategy, the developed ECL immunosensing platform exhibited sensitive response to PSA in a linear range of 1.0 × 10−5 _ 50 ng mL−1 with a low detection limit of 0.0045 pg mL−1 (S/N = 3). This work provided a promising tool in early clinical diagnostics of prostate cancer.

CeO2/MXene heterojunction-based ultrasensitive electrochemiluminescence biosensing for BCR-ABL fusion gene detection combined with dual-toehold strand displacement reaction for signal amplification

An “on-off” nonenzymatic and ultrasensitive electrochemiluminescence (ECL) biosensing platform has been constructed to detect BCR-ABL fusion gene based on CeO2/MXene heterojunction and configuration-entropy driven dual-toehold strand displacement reaction (DT-SDR) for signal amplification. The CeO2/MXene heterojunction were prepared via one-step hydrothermal method through in situ synthesis of CeO2 nanocubes on the surface of Ti3C2-MXene nanosheets. Surprisingly, the prepared CeO2/MXene heterojunction with good dispersion and excellent conductivity not only significantly enhanced ECL emission of S2O82−/O2 system, but also acted as good electrode modification materials to provide massive active sites for three-stranded ST/AS/BK complex immobilization. In the presence of target BCR-ABL fusion gene and Bio-FS, target BCR-ABL fusion gene bound to dual-toehold exposed at the ends of ST, replacing AS and BK and obtaining ST/target with a loop. Subsequently, Bio-FS bound to the loop (as toehold) in ST strand of ST/target to form ST/Bio-FS, replacing the target to further trigger a new SDA cycle. This configuration-entropy driven DT-SDR made three-stranded ST/AS/BK complex transform into dual-stranded ST/Bio-FS in the electrode interface. Ultimately, the quenching labels of streptavidin modified Pt nanoparticles functionalized polydopamine composites (SA-Pt@PDA) were introduced via biotin and streptavidin recognition, realizing ECL emission quenching of S2O82−/O2 system for “on-off” detection of BCR-ABL fusion gene. The developed ECL biosensor for BCR-ABL fusion gene detection achieves the wide concentration variation from 1 fM to 100 pM with low limit of detection down to 0.27 fM, which provides new enlightenment and basis for molecular diagnosis of chronic myelogenous leukemia in clinical practice.

Sensitive electrochemiluminescence biosensing of polynucleotide kinase using the versatility of two-dimensional Ti3C2TX MXene nanomaterials

Electrochemiluminescence (ECL) is a powerful readout method for the development of (bio)sensors, whose performances depend on the electrode materials and the architecture of its surface. Herein, we demonstrate that the precise control of the sensing interface using the versatility of two-dimensional (2D) transition metal carbides (Ti3C2TX MXene) leads to the enhancement of the ECL signal. This electrode material, which exhibits remarkable structural and electrochemical properties was decorated by the in situ formation of gold nanoparticles (AuNPs) owing to the Ti reducibility. Then, a large amount of the luminophore, Ru(bpy)32+, was immobilized on Ti3C2TX MXene thanks to its unique negative charge and large specific surface area to obtain Ru–Ti3C2TX-AuNPs. The presented approach exploits the high catalytic activity and excellent conductivity of this 2D nanomaterial as illustrated by the enhanced ECL emission performance of the Ru–Ti3C2TX-AuNPs nanoprobes. Finally, DNA phosphorylated with polynucleotide kinase (PNK) was recognized efficiently by the chelation between Ti and phosphate group. A highly sensitive and selective ECL biosensor was developed for the detection of PNK and the screening of its inhibitors. A lower detection limit of 0.0002 U mL−1 and wide linear relationship ranged from 0.002 to 10 U mL−1 were obtained. Furthermore, the practicality of our method was tested in MCF-7 cell lysate, which opens enticing perspectives for future applications of Ti3C2TX materials in the ECL bioanalysis field.

Modular engineering of gold-silver nanocluster supermolecular structure endow strong electrochemiluminescence for ultrasensitive bioanalysis

Here, the gold-silver nanocluster supramolecular network (AuAg NCs) is synthesized by the assembly of Au nanoclusters (Au NCs) and Ag NCs via host-guest complexation between 6-aza-2-thiothymine as the stabilizer of Au NCs and L-arginine as the stabilizer of Ag NCs in solution, whose electrochemiluminescence (ECL) emission is not only exceptionally stronger than that of discrete monometallic NCs, but also more significant than that of agminated monometallic NCs. The dramatically enhanced ECL emission of self-assembled AuAg NCs originates from the synergistic effect of aggregation-induced enhancement and silver effect in gold catalysis. As a proof of concept, the self-assembled AuAg NCs is successfully applied in the ultrasensitive detection of breast cancer biomarker microRNAs-21 (miR-21), which guides a new pathway for creating high-quality nano-optical elements in chemical sensors, biological imaging, and lightemitting devices.

Aggregation-Induced Electrochemiluminescence of Tetraphenylbenzosilole Derivatives in an Aqueous Phase System for Ultrasensitive Detection of Hexavalent Chromium.

Herein, aggregation-induced electrochemiluminescence (AIECL) of tetraphenylbenzosilole derivatives in an aqueous phase system with the participation of a co-reactant was systematically investigated for the first time. All organics that we studied exhibit excellent stability and dramatically enhanced electrochemiluminescence (ECL) and photoluminescence (PL) emission when the water fraction increases. The influence of substituents in the structure of tetraphenylbenzosilole derivatives on AIECL performance was proved by fluorescence, cyclic voltammetry, and related theoretical calculation. Among them, 2,3-bis(4-cyanophenyl)-1,1-diphenyl-benzosilole (TPBS-C) with strong electron-withdrawing cyano groups exhibits the best ECL behavior with the highest ECL efficiency (184.36%). The strongest ECL emission of TPBS-C not only stems from the aggregated molecules that restrict the intramolecular motion of peripheral phenyl groups, which inhibits the nonradiative transition, but also comes from the fact that TPBS-C has the lowest reduction potential, and twice the reduction process of TPBS-C occurs to produce more anion radicals (TPBS-C·-). Significantly, the ECL sensor based on TPBS-C nanoaggregates exhibits excellent detection performance for toxic Cr(VI) with a wide linear range from 10-12 to 10-4 M and an extremely low detection limit of 0.83 pM. This work developed an efficient luminophore with unique AIECL properties and realized the ultrasensitive detection of Cr(VI) in the aqueous phase system.

Two-dimensional black phosphorus nanoflakes: A coreactant-free electrochemiluminescence luminophors for selective Pb2+ detection based on resonance energy transfer

As a nondegradable environmental pollutant, lead ion (Pb2+) has been proven to be deleterious for environmental and health. Conveniently, quickly and accurately on-site detection of Pb2+ is of paramount importance. Herein, an electrochemiluminescence (ECL) assay protocol using two-dimensional black phosphorus (2D BP) nanoflakes as new ECL emitter for highly sensitive and selective trace Pb2+ was designed on the basis of Pb2+ induced ECL resonance energy transfer (ECL-RET) between 2D BP nanoflakes and Ag/AgCl nanocubes. Anodic green ECL emission of BP nanoflakes without any coreactants was achieved. It is noteworthy that the possible ECL mechanism and the influence of coreactants on the ECL behaviour of BP nanoflakes were further investigated. Benefitting from the well match between the ECL emission spectrum of BP nanoflakes (∼510 nm) and the absorption spectrum of Ag/AgCl nanocubes (200−300 nm and 400−700 nm), effective energy transfer yielded. The introduction of Pb2+ would lead to the detachment of Ag/AgCl nanocubes then result in an enhanced ECL emission. Based on this, the proposed method could accurately quantify the Pb2+ in the range from 0.5 pM to 5 nM, which exhibited comparative performance to previous work. Furthermore, this study presents the example of employing 2D BP nanoflakes as ECL emitters and constructing a coreactant-free ECL sensing platform, which might open up a promising route for the potential design and implement in clinical analysis.

Tracking Magnetic Rotating Objects by Bipolar Electrochemiluminescence.

There has been a very rapid development of original systems that can be remotely controlled or addressed by playing with chemical and physical concepts. Here, we present the synergetic combination of external magnetic and electric fields to promote, in a double contactless mode, the rotational motion and the concomitant generation of light emission at the level of a gold-coated iron wire. The latter can be moved by rotating magnetic fields. Simultaneously, an electric field induces its remote polarization, which triggers the local generation of electrochemiluminescence (ECL) by bipolar electrochemistry. During rotation, the motion is tracked by changes in ECL intensity as a function of the orientation of the conducting wire in the electric field. The ECL behavior of the rotating bipolar wire is rationalized by considering the angular dependence of the polarization. Unlike previously reported systems, the rotation induces enhanced ECL emission due to the convective flow produced by the motion. This demonstrates that ECL emission can be coupled to magnetically controlled rotating bipolar objects. Such dual magnetically and electrically addressable dynamic systems open exciting prospects for integrating new functions such as imaging and sensing capabilities.

Dual Enhanced Electrochemiluminescence of Aminated Au@SiO2/CdS Quantum Dot Superstructures: Electromagnetic Field Enhancement and Chemical Enhancement.

This paper reports dual enhanced electrochemiluminescence (ECL) of CdS quantum dot (QD)-decorated aminated Au@SiO2 core/shell (Au@SiO2-NH2/CdS) superstructures. A maximum ECL emission of the Au@SiO2-NH2/CdS superstructures (Au core, ca. 55 nm) with a silica shell of 38 nm was 35-fold stronger than that of the counterparts (containing neither Au cores nor amino groups) with H2O2 as a coreactant. The fold of ECL enhancement is the largest, and the optical path of maximum ECL enhancement is the longest reported so far. The larger the Au cores in the superstructures, the stronger the ECL emission of CdS QDs was. Two types of ECL enhancement mechanisms were clearly proposed for the dual enhanced ECL of the Au@SiO2-NH2/CdS superstructures. One was the electromagnetic field enhancement induced by localized surface plasmon resonance of Au cores, and the other was the chemical enhancement from amino groups modified on the silica surface involved in the ECL process in the assistance of H2O2. It is the first time to put forward the new concept of chemical enhanced ECL that was directly related to the participation of other chemicals, which caused a decrease in the difference in the redox potential between emitters and coreactants for the increase of their redox currents. The constructed ECL platform was demonstrated to have promising applications in highly sensitive detection of glutathione (GSH), and the response mechanism of GSH was also explored.

Ultrasensitive detection of protein kinase activity based on the Au NPs mediated electrochemiluminescence amplification of S2O82−–O2 system

An electrochemiluminescence (ECL) biosensor based on Au NPs enhanced ECL signal of S2O82−–O2 system has been constructed for ultrasensitive detection of protein kinase activity. In the presence of ATP-s and protein kinase A (PKA), Au NPs can be captured on the thoil-phosphorylated peptides modified electrode surface, generating an enhanced ECL emission of S2O82−–O2 system. With increasing the PKA activity, more Au NPs can be captured on the modified electrode surface, resulting in the gradually enhanced ECL intensity of S2O82−–O2 system. Based on the Au NPs mediated the ECL amplification of S2O82−–O2 system, the activity of PKA can be detected sensitively with a limit of detection of 0.0002U/mL, which is much lower than the most sensitive method in previous reports. The good conductivity and high catalytic ability of the Au NPs are revealed to account for the enhanced sensitivity in this ECL biosensor. The ECL biosensor has been successfully used for monitoring PKA activity in biological samples and screening of protein kinase inhibition.

Ultrasensitive immunoassay of insulin based on highly efficient electrochemiluminescence quenching of carboxyl-functionalized g-C3N4 through coreactant dual-consumption by NiPd-DNAzyme

An efficient quenching electrochemiluminescence (ECL) immunosensor for highly sensitive detection of insulin was constructed using carboxyl-functionalized g-C3N4 (C-g-C3N4) as an ECL emitter and hollow NiPd nanoparticles loading with G-quadruplex/hemin DNAzyme (NiPd-DNAzyme) as the dual-quenching probe. In this protocol, the as-prepared C-g-C3N4 served as both a luminophore and the matrix to immobilize capture antibody (Ab1) by amide linkage, which exhibiting strong ECL activity in the presence of the coreactant H2O2. The NiPd showed good peroxidase-activity and loading capacity for both G-quadruplex/hemin DNAzyme and detection antibody (Ab2). The dual-peroxidase nature of NiPd-DNAzyme composite highly promoted the reduction of H2O2, resulting in the consumption of the coreactant of C-g-C3N4 and obvious ECL quenching. Using insulin as a model analyte, the change of ECL intensity was logarithmically related to the concentration of the insulin in the range from 0.1 pg·mL−1 to 20.0 ng·mL−1 with a detection limit of 33 fg·mL−1. The wide detection range and high sensitivity resulted from the enhanced ECL emission and highly efficient quenching ability of NiPd-DNAzyme. Furthermore, the ECL immunosensor presented good stability, repeatability and selectivity, which demonstrate that it will be potential in clinical application.

Aggregation-Induced Enhanced Electrochemiluminescence from Organic Nanoparticles of Donor-Acceptor Based Coumarin Derivatives.

Organic nanoparticles (NPs) from donor-acceptor based coumarin derivatives, 6-[4-(N,N-diphenylamino)phenyl]-3-ethoxycarbonyl coumarin (DPA-CM), with an average size of 5.82 nm, were synthesized by a facile reprecipitation method using water as a poor solvent and tetrahydrofuran as a good solvent. Red-shifted absorption, blue-shifted photoluminescence emission, and aggregation-induced enhanced electrochemiluminescence (ECL) emission were observed for the DPA-CM NPs in aqueous solution compared with the original DPA-CM in organic solution. The aggregation-induced enhanced ECL emission is ascribed to the combined effects of the small size of the DPA-CM NPs, the restricted conformational relaxation in the NPs, and the good stability of the cationic radical of DPA-CM. A strong and stable ECL emission is obtained at the DPA-CM NPs modified glassy carbon electrode in the presence of tri-n-propylamine, and the ECL intensity of the DPA-CM NPs modified electrode is quenched linearly in the range of 0.05-50 μM with detection limit of 0.04, 0.2, and 0.4 μM for ascorbic acid, uric acid, and dopamine, respectively. This work shows an example of donor-acceptor based organic NPs as ECL emitters and their analytical applications to monitor biomolecules.

Ru(bpy)32+ Incorporated Luminescent Polymer Dots: Double-Enhanced Electrochemiluminescence for Detection of Single-Nucleotide Polymorphism.

Encapsulating a large amount of electrochemiluminescence (ECL) active molecules into one nanoparticle for single-target recognition can greatly improve the sensitivity of the ECL assay. This work used luminescent conjugated polymer as a carrier to synthesize Ru(bpy)32+-doped polymer dots (RuPdots). The RuPdots with an average size of 20 nm and encapsulation of about 1354 Ru(bpy)32+ showed greatly enhanced ECL emission. Using tripropylamine as a coreactant, the resonance energy transfer from the excited polymer dots to the encapsulated Ru(bpy)32+ was demonstrated, which led to a 15.7-fold higher ECL emission than that of Ru(bpy)32+ with the same amount at the gold electrode. By coupling the double-enhanced ECL signal of this nanostructure with the specific ligase detection reaction, a sensitive ECL biosensor was constructed for specific detection of a single-nucleotide polymorphism (SNP). Using mutant KRAS gene as a model target, the ECL SNP detection method showed a linear range from 1 fM to 1 nM and a detection limit of 0.8 fM. The designed RuPdots provided a novel signal amplification strategy and could be used as a universal label for ultrasensitive ECL biodetection.

Enhanced Electrochemiluminescence on Indium Tin Oxide Modified with Dendrimer-Encapsulated Nanoparticles

Here, we report enhanced electrochemiluminescence (ECL) on indium tin oxide (ITO) electrodes modified with amine-terminated dendrimers encapsulating catalytic nanoparticles, which can be applied for sensitive electrochemiluminescence(ECL)-based assay. Specifically, we prepared Pt and Au dendrimer-encapsulated nanoparticles (DENs) using amine-terminated polyamidoamine (PAMAM) dendrimers, and subsequently immobilized the DENs onto ITO surfaces via electrooxidative grafting of the terminal amines of dendrimers to the surfaces.[1] The resulting DEN-modified ITOs preserved good optical transparency of ITO and exhibited highly catalyzed electrochemical oxidation of Ru(bpy)3 2+ (bpy, 2,2’-bipyridine)/ tri-n-propylamine (TPrA), leading to significantly increased ECL emission.[2] Especially, the Pt DEN-modified ITO electrode provides negligible transmittance drop, i.e. only ~1.99% over the entire visible region, and exhibited not only much enhanced (i.e., ~213-fold increase compared to ECL obtained from bare ITO), but also stable ECL emission under consecutive potential scans from 0.00 to 1.10 V for 10 cycles, which allowed ~329 times more sensitive ECL-based analysis of nicotine using the Pt DEN-modified ITO compared with the use of bare ITO. However, we observed relatively poor stability of Au DENs on the ITO surfaces.[2] We found that the poor stability of Au DENs is closely related with the presence of chloride ions in electrolyte solutions.[3] In the absence of chloride ions, we demonstrated that the Au DEN-modified ITOs could be used as a versatile ECL based platform for sensitive electroanalysis of reactive oxygen species (ROS), such as hydrogen peroxide. [1] S. B. Lee, Y. Ju, Y. Kim, C. M. Koo, and J. Kim, Chem . Com un . 2013, 49, 8913. [2] Y. Kim and J. Kim, Anal . C hem . 2014, 86, 1654. [3] Lee, S. B.; Kwon, J.; Kim, J. Electroanalysis 2015 , 27, 2180-2186.

Functionalization of indium tin oxide electrode with both of dendrimer-encapsulated Pt nanoparticles and chemically converted graphenes for enhanced electrochemiluminescence of luminol/H2O2

Here, we report highly enhanced electrochemiluminescence (ECL) of luminol in the presence of H2O2 on indium tin oxides (ITOs) modified with both of dendrimer-encapsulated Pt nanoparticles (Pt DENs) and chemically converted graphenes (CCGs). The ITO electrodes were electrochemically modified with size-monodisperse Pt DENs via electrooxidative grafting of the terminal amines of the dendrimers encapsulating Pt nanoparticles. The Pt DEN-modified ITOs were then decorated with CCG sheets via electrostatic attachments of graphene oxides (GOs) and subsequent chemical reduction of the GOs to the CCGs. The resulting CCG-Pt DEN/ITO electrodes exhibited highly catalyzed electrochemical oxidation of luminol/H2O2, leading to significantly enhanced ECL of the luminol/H2O2 system, i.e., ∼15-fold enhancement, compared to ECL emission from bare ITOs even at lower applied potentials, which allowed sensitive ECL-based analysis of H2O2 using the CCG-Pt DEN/ITOs. Graphical abstract We report the highly enhanced electrochemiluminescence of the luminol/H2O2 system on the indium tin oxide electrodes modified with both of Pt nanoparticles and chemically converted graphenes using amine-terminated dendrimers.

Enhanced Electrochemiluminescence of Luminol on Indium Tin Oxide Modified with Dendrimer‐Encapsulated Au Nanoparticles

AbstractEnhanced electrochemiluminescence (ECL) of luminol was reported with the use of dendrimer‐encapsulated Au nanoparticle (Au DEN)‐modified ITOs in the presence of hydrogen peroxide, which was applied for sensitive ECL‐based electroanalysis of hydrogen peroxide. The enhanced ECL of luminol in the presence of hydrogen peroxide was attributed to facile electrochemical oxidation of luminol/hydrogen peroxide on the Au DEN‐modified ITOs at potentials as low as ∼0.4 V (vs. Ag/AgCl). Spooling ECL spectroscopy measurements indicated that the enhanced ECL emission of luminol/hydrogen peroxide system on the Au DEN‐modified ITOs originated from excited 3‐aminophthalate as same as that obtained on bare ITOs. Stability of Au DENs on ITO surfaces was also addressed and found to be closely related with the presence of chloride ions in electrolyte solutions.