Ru(bpy)3-doped silica nanoparticle DNA probe for the electrogenerated chemiluminescence detection of DNA hybridization

A sensitive electrogenerated chemiluminescence (ECL) detection of DNA hybridization, based on tris(2,2′-bipyridyl)ruthenium(II)-doped silica nanoparticles (Ru(bpy)₃²⁺-doped SNPs) as DNA tags, is described. In this protocol, Ru(bpy)₃²⁺-doped SNPs was used for DNA labeling with trimethoxysilylpropydiethylenetriamine(DETA) and glutaraldehyde as linking agents. The Ru(bpy)₃²⁺-doped SNPs labeled DNA probe was hybridized with target DNA immobilized on the surface of polypyrrole (PPy) modified Pt electrode. The hybridization events were evaluated by ECL measurements and only the complementary sequence could form a double-stranded DNA (dsDNA) with DNA probe and give strong ECL signals. A three-base mismatch sequence and a non-complementary sequence had almost negligible responses. Due to the large number of Ru(bpy)₃²⁺ molecules inside SNPs, the assay allows detection at levels as low as 1.0 × 10⁻¹³ mol l⁻¹ of the target DNA. The intensity of ECL was linearly related to the concentration of the complementary sequence in the range of 2.0 × 10⁻¹³ to 2.0 × 10⁻⁹ mol l⁻¹.     

Electrochemiluminescent determination of nicotine based on tri(2,2′-bipyridyl) ruthenium (II) complex through flow injection analysis

This paper describes the electrogenerated chemiluminescence (ECL) processes of Ru(bpy)₃²⁺/nicotine system at ITO working electrode. An ECL-based method for rapid and sensitive detection of nicotine in phosphate buffer solution at pH 8.0 is established. Strong ECL emission was observed at a positive potential of 1.4 V vs. Ag/AgCl. A possible ECL mechanism is proposed for the Ru(bpy)₃²⁺/nicotine system, the oxidation product of nicotine at the electrode surface reacts with the 3+ state of ruthenium bipyridyl (2+) complex and form ruthenium complex exited state ions and thus releases photons. Effect of pH (medium/electrolyte), working potential, buffer composition, buffer concentration, reactant and co-reactant (nicotine) concentration, flow rate and loop size on the ECL spectrum of the Ru(bpy)₃²⁺/nicotine were studied. At the optimized experimental conditions, lower detection limit for nicotine was observed as 1.2 nmol L⁻¹ (S/N = 3). Linear relationship between ECL current and concentration of nicotine was observed (up to 100 μmol L⁻¹) with R-value of 0.997. The relative standard deviation with 5 μmol L⁻¹ concentration of nicotine for 20 analyses was only 1.4%. A 94% recovery rate was observed in a real sample analysis without any complications/disturbance in measurement. Interferences of humid acid, camphor and SDS were not observed in their presence in the sample solution. The established procedure for nicotine quantification manifests fascinating results and can be suggested for further applications.     

Characterization of electrochemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with glyphosate as coreactant in aqueous solution

Glyphosate, a phosphorus-containing amino acid type herbicide was used as a coreactant for studying of electrochemiluminescence (ECL) reaction of tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)₃²⁺] in an aqueous solution. In a phosphate buffer solution of pH 8, glyphosate itself was known to be electrochemically inactive at glassy carbon electrode, however, it participated in a homogeneous chemical reaction with the electrogenerated Ru(bpy)₃³⁺, and resulted in producing Ru(bpy)₃²⁺ species at the electrode surface. Kinetic and mechanistic information for the catalysis of glyphosate oxidation were evaluated by the steady-state voltammetric measurement with an ultramicroelectrode. The simulated cyclic voltammogram based on this mechanism was in good agreement with that obtained experimentally. ECL reaction of Ru(bpy)₃²⁺/glyphosate system was found to be strongly dependent on the media pH. In a pH region of 5-9, an ECL wave appeared at ca. +1.1 V vs. Ag/AgCl, which was caused by the generation of *Ru(bpy)₃²⁺ via a Ru(bpy)₃³⁺-mediated oxidation of glyphosate. When pH >10, a second ECL wave was observed at ca. +1.35 V vs. Ag/AgCl, which was believed to be associated with a reaction between Ru(bpy)₃³⁺ and the species from direct oxidation of GLYP at a GC electrode surface.     

EQCM study of the ECL quenching of the tris(2,2′-bipyridyl)ruthenium(II)/tris-n-propylamine system at a Au electrode in the presence of chloride ions

Significant effect of chloride ions on the electrogenerated chemiluminescence (ECL) behavior of the ruthenium(II)tris(2,2′-bipyridine) (Ru(bpy)₃²⁺)/tri-n-propylamine (TPrA) system at a Au electrode was reported. At low concentrations (e.g., [Cl⁻] < 5 mM), the ECL was enhanced; at relatively high concentrations, however, the ECL intensity decreased with the increase of the [Cl⁻]. At [Cl⁻] = 90 mM, ∼50% and 100% ECL inhibition was observed for the first and the second ECL wave, respectively. The electrogenerated gold-chloride complexes (AuCl₂⁻ and AuCl₄⁻) which were verified using an electrochemical quartz-crystal microbalance (EQCM) method were found to be responsible for the ECL inhibition. This study suggests that care must be taken when a Au working electrode is used for ECL studies in chloride-containing buffer solutions (widely used in DNA probes) and/or with the commonly used chloride-containing reference electrodes since in these cases the ECL behavior may significantly disagree with that obtained using other electrodes and reaction media.     

Hydroxyl radical-related electrogenerated chemiluminescence reaction for a ruthenium tris(2,2′)bipyridyl/co-reactants system at boron-doped diamond electrodes

An electrogenerated chemiluminescence (ECL) reaction of the Ru(bpy)₃²⁺ (2,2′-bipyridyl, bpy)/co-reactant system in the extremely high-potential region (over 2.6 V versus Ag/AgCl) was probed using a boron-doped diamond (BDD) electrode. At the BDD electrode, three ECL waves (1.25, 2.30 and 3.72 V) were observed in cyclic voltammograms for 20 mM ascorbic acid (AA). For the ECL peaks observed at 1.25 V corresponding to the oxidation potential for Ru(bpy)₃²⁺ (1.15 V), the light intensities and current densities were found to depend on the square root of the AA concentration. This suggests that AA oxidation, followed by the formation of the reducing radical that is necessary for generating the excited state of Ru(bpy)₃^2+* occurred through homogeneous electron-transfer between Ru(bpy)₃³⁺ and the AA species. However, for the ECL peaks at 2.30 V, the current densities and light intensities linearly increased with increasing AA concentration, suggesting that the reducing radical was formed through the direct oxidation at the electrode surface. The ECL reaction at 3.72 V was observed only at the BDD electrode and not at other electrodes. The onset potentials for the light intensity were approximately 2.6 V, independently of the type of the co-reactants (e.g. 2-propanol and AA). The peak potentials exhibited linear relation with the co-reactant concentration. In the analysis of the ECL intensity for various co-reactants (alcohols) that show different reactivity for the hydrogen abstraction reaction, the order of the light intensities at the peaks for alcohols was found to be consistent with that for the rate constants of the hydrogen abstraction reaction. These results indicate that the co-reactant radical was formed through the hydrogen abstraction reaction with the hydroxyl radical (HO) generated during the oxygen evolution reaction.     

Influence of nature, concentration and pH of buffer acid-base system on rate determining step of the electrochemiluminescence of Ru(bpy)3 with tertiary aliphatic amines

The electrogenerated chemiluminescence (ECL) of Ru(bpy)₃²⁺ (bpy = 2,2′-bipyridyl) with tertiary aliphatic amines as co-reactants, was theoretically and experimentally studied as a function of the pre-equilibria involved in the ammonium proton lost and in relation to the nature of the rate determining step. Transient potential steps were used with a 3-mm glassy carbon disk electrode or carbon fiber ultramicroelectrodes array to investigate emission behavior in a variety of aqueous solution types, containing phosphate, tartrate and phthalate acid-base systems at differing pH values. The emission of Ru(bpy)₃²⁺ resulting from the reaction with n-tripropylamine (TPrA), tri-isobutylamine (TisoBuA), n-tributylamine (TBuA), methyl-di-n-propylamine (MeDPrA) and triethylamine (TEtA) in varying acid-base media was interpreted on the basis of the quoted pre-equilibria, ammonium pK_a being known. The nature of the rate determining steps changes depending on pH. Above pH ≈ 5 the amine neutral radical formation is the rate determining step and, is independent of pH with rate constant close to 10³ s⁻¹; below pH ≈ 5 the rate determining step becomes the deprotonation of the ammonium ion, operated by different bases present in solution. Different amines in the same acid-base system showed analogous ECL behavior, conditioned by the chosen acid base system. A single amine in different acid-base systems showed different kinetic behaviors, due to the dissociation constants of the chosen buffers. The concentration of the acid-base system also played an important role and influenced emission intensity and shape. ECL emission were simulated by finite difference methods, implementing a previously proposed mechanism by including the relevant pre-equilibria. Simulation may also give estimates of the pK_a values of the ammonium ions. An ion pair formation between R₃N⁺ and the mostly charged species present in solution is hypothesized to explain the contradictory experimental results concerning the reaction mechanism of the proton lost of the radical cation.     

Electrochemiluminescent behavior of luminol on the glassy carbon electrode modified with CoTPP/MWNT composite film

A glassy carbon electrode (GCE) modified with cobalt(II) meso-tetraphenylporphrine/multiwall-carbon nanotube (CoTPP/MWNT) was applied to investigate the electrochemiluminescent (ECL) behavior of luminol. The ECL intensity of luminol was found to be increased greatly on this modified electrode. The presence of cobalt(II) meso-tetraphenylporphrine (CoTPP) can catalyze the reduction of oxygen on the electrode surface to produce HOO⁻, which can increase the ECL intensity of luminol. Moreover, MWNT can provide the more effective area of the electrode, and can act as a promoter to enhance the electrochemical reaction. The proposed method enables a detection limit for luminol of 1.0 × 10⁻⁸ mol/L in the neutral solution. Under the optimum condition, the enhanced ECL intensity of luminol by H₂O₂ had a linear relationship with the concentration of H₂O₂ in the range of 1.0 × 10⁻⁷ to 8.0 × 10⁻⁸ mol/L with the detection limit of 5.0 × 10⁻⁹ mol/L.     

Mediated oxidation of guanine by [Ru(bpy)2dpp] and their electrochemical assembly on the ITO electrode

Electrochemical oxidation of guanine mediated by [Ru(bpy)₂dpp]²⁺ (where bpy = 2,2′-bipyridine, dpp = 2,3-bis (2-pyridyl) pyrazine) and their electrochemical assembly at an ITO electrode prompted by guanine have been investigated with cyclic voltammetry and differential pulse voltammetry. It is found that [Ru(bpy)₂dpp]²⁺ can serve as an excellent mediator to induce the oxidation of guanine, and the mediated peak currents increase linearly with the rise of guanine concentration in the range from 0.01 to 0.20 mmol L⁻¹. Interestingly, with the increase of repetitive voltammetric sweeping numbers, [Ru(bpy)₂dpp]^3+/2+ can be assembled onto the ITO electrode and guanine has the ability to enhance the peak currents of prewaves. Also, with the rise of guanine concentration from 0.01 to 0.15 mmol L⁻¹, the peak currents of prewaves increase gradually. Meanwhile, the mediated mechanism of guanine oxidation by [Ru(bpy)₂dpp]²⁺ and the assembled process of [Ru(bpy)₂dpp]^3+/2+ on the ITO surface in the presence of guanine are discussed in detail.     

Cd transfer across water/1,2-dichloroethane microinterfaces facilitated by complex formation with 1,10-Phenanthroline

The transfer of Cd²⁺ facilitated by 1,10-Phenanthroline (phen) was investigated at the microinterface of two immiscible electrolyte solutions, hosted by a 25 μm diameter orifice of a micropipette. Cyclic voltammetry (CV) was employed to examine the transfer in the conditions of the ligand (organic phase) in excess and Cd²⁺ (aqueous phase) in excess. In these conditions, asymmetric (peak-shaped in the forward scan and steady state in the backward scan), and reversible steady state (for the two scan directions) voltammograms were observed. The dependence of half-wave potential on the ligand concentration suggested that the equilibrium was effectively displaced towards a 1:3 (Cd²⁺:ligand) stoichiometry, with a formation constant, β₃ = 3.9 × 10²⁹. The diffusion coefficients of Cd²⁺ in the aqueous solution and those of phen, Cd(phen)₃²⁺ in organic phase were evaluated to be 6.5 × 10⁻⁶, 5.8 × 10⁻⁶, and 5.1 × 10⁻⁶ cm² s⁻¹ respectively, using CV.     

An electrochemiluminescent biosensor for vitamin C based on inhibition of luminol electrochemiluminescence on graphite/poly(methylmethacrylate) composite electrode

A novel graphite/poly(methyl methacrylate) (graphite/PMMA) electrode was prepared in this paper. It was found that the developed polymer graphite paste electrode has some advantages in electrochemistry and electrochemiluminescence (ECL), such as high sensitivity, good reproducibility, quick and wide linear range of response to some biomolecules. The ECL behavior of luminol has been investigated in detail at the graphite/PMMA electrode, and vitamin C was found to be able to inhibit this ECL system. Based on which an inhibited ECL detection method has been developed for determination of vitamin C in this paper. The proposed method exhibited good reproducibility, wide-range linearity, high sensitivity and stability with a detection limit of 8.3 × 10⁻⁹ mol L⁻¹ (signal-to-noise ratio = 3) and linear response range of 2.5 × 10⁻⁸-1.0 × 10⁻⁴ mol L⁻¹. The relative standard deviation was 2.3% for 5 × 10⁻⁶ mol L⁻¹ vitamin C (n = 9). The possible mechanism for inhibition of luminol on graphite/PMMA electrode has also been proposed.     

High lithium conductivities in weakly-ionophilic low-dimensional block copolymer electrolytes

The structure of amphiphilic low-dimensional copolymer electrolytes I of similar overall composition but prepared by different synthetic procedures X and Y are described. I are copolymers of poly[2,5,8,11,14-pentaoxapentadecamethylene(5-alkyloxy-1,3-phenylene)] (CmO5) and poly[2,-oxatrimethylene(5-alkyloxy-1,3-phenylene)] (CmO1) where the alkyl side chains having m carbons are hexadecyl or mixed dodecyl/octadecyl (50/50). ¹H NMR shows that the copolymers have 50% (m = 16) or only 18 and 13% of CmO5 units and DSC indicates that the copolymers have ‘block’ sequencing of CmO1 and CmO5 segments. Molecular dynamics modelling indicates that in CmO5 Li⁺ and BF₄⁻ ions are separated by Li⁺ encapsulation in tetraethoxy segments but in ionophobic CmO1 units the salt is mostly present as neutral aggregates decoupled from the polymer. Conductivities of these microphase-separated mixtures with salt-bridge amphiphilic polyethers II and III of each system are similar. They have low temperature dependence over the range 20 °C to 110 °C at ∼10⁻³ S cm⁻¹. ⁷Li NMR linewidth measurements confirm high lithium mobilities at −20 °C. A conduction mechanism is proposed whereby Li⁺ hopping takes place along rows of decoupled aggregates (dimers/quadrupoles) within an essentially block copolymer structure. Subambient measurements to −10 °C gave a conductivity of 4 × 10⁻⁵ S cm⁻¹.     

Study of boron doping in MPCVD grown homoepitaxial diamond layers based on cathodoluminescence spectroscopy, secondary ion mass spectroscopy and capacitance-voltage measurements

Boron incorporation from the gas phase was achieved in MPCVD grown (100)-oriented homoepitaxial diamond layers, either with or without a small fraction of oxygen in the gas phase, in addition to hydrogen, methane and diborane. From secondary Ion Mass Spectroscopy (SIMS), it is shown that the 0.25% of oxygen decreases the Boron concentration [B] by two orders of magnitude. In this way, we demonstrate that it becomes possible to control [B] with low levels of compensation and passivation down to the 10¹⁵ cm^− 3 range. Cathodoluminescence spectroscopy is systematically performed in seventeen samples under a 10 kV acceleration voltage at 5 K and the exciton bound to boron (BE_TO) intensity to the free exciton (FE_TO) intensity ratio is evaluated (I_BETO/I_FETO). A linear relationship between I_BETO/I_FETO and [B] with a coefficient of 3.5 × 10¹⁶ cm^− 3 is demonstrated for [B] < 3 × 10¹⁷ cm^− 3 in single crystalline diamond, irrespective of the gas phase composition during growth.     

Electrooxidation of sulfide by cobalt pentacyanonitrosylferrate film on glassy carbon electrode by cyclic voltammetry

A glassy carbon (GC) electrode was modified with cobalt pentacyanonitrosylferrate (CoPCNF) film. Cyclic voltammetry (CV) of the CoPCNF onto the GC (CoPCNF/GC) shows a redox couple (Fe^III/Fe^II) with a standard potential (E^0′) of 580 mV. The current ratio I_pa/I_pc remains almost 1, and a peak separation (ΔE_p) of 106 mV is observed in 0.5 M KNO₃ as the supporting electrolyte. Anodic peak currents were found to be linearly proportional to the scan rate between 10 and 200 mV s⁻¹, indicating an adsorption-controlled process. The redox couple of the CoPCNF film presents an electrocatalytic response to sulfide in aqueous solution. The analytical curve was linear in the concentration range of 7.5 × 10⁻⁵ to 7.7 × 10⁻⁴ M with a detection limit of 4.6 × 10⁻⁵ M for sulfide ions in 0.5 M KNO₃ solution.     

A glassy carbon supported bilayer lipid-like membrane of 5,5-ditetradecyl-2-(2-trimethyl-ammonioethyl)-1,3-dioxane bromide for electrochemical sensing of epinephrine

A self-assembled bilayer lipid-like membrane (BLM) supported on glassy carbon electrode (GCE) was fabricated using 5,5-ditetradecyl-2-(2-trimethyl-ammonioethyl)-1,3-dioxane bromide (DTDB) for epinephrine (EP) determination in the presence of ascorbic acid (AA). This modified electrode (DTDB/GCE) has strong membrane adsorption accumulation and electrocatalytic ability toward EP and AA. The oxidation of EP was controlled by double step adsorption accumulation process of the DTDB-BLM. The parameters of fitted Langmuir isotherm Γ_max, B_ADS, and ΔG_ADS values were determined as 1.0×10⁻¹¹ mol cm⁻², 2.04×10⁶ dm³ mol⁻¹, and −45.17 kJ mol⁻¹ for the fist step for EP concentration less than 1 mM, and 4.92×10⁻¹¹ mol cm⁻², 7.35×10⁴ dm³ mol⁻¹, and −37.1 kJ mol⁻¹ for the second step for EP concentration higher than 1 μM. The DPV peaks for EP and AA oxidations were appeared at 0.220 and 0.085 V versus SCE, respectively, allowing the determination of EP in the presence of high concentration of AA. The advantage of DTDB-BLM was demonstrated experimentally in comparison with other three BLMs, and attributed to the dioxane group as well as the suitable length of the carbon chain of DTDB molecule. The current response of the DTDB/GCE was fast and reproducible, suitable for the electrochemical sensing in flow-injection systems. A linear range of 1×10⁻⁸ to 1×10⁻⁴ M EP was preliminary obtained using a simple setup.     

Enhanced solid-state electrogenerated chemiluminescence of Au/CdS nanocomposite and its sensing to H2O2

Au nanoparticles (AuNPs) are good quenchers once they closely contact with luminophore. Here we reported a simple approach to obtain enhanced electrogenerated chemiluminescence (ECL) behavior based on Au/CdS nanocomposite films by adjusting the amount of AuNPs in the nanocomposite. The maximum enhancement factor of about 4 was obtained at an indium tin oxide (ITO) electrode in the presence of co-reactant H₂O₂. The mechanism of this enhancement was discussed in detail. The strong ECL emission from Au/CdS nanocomposites film was exploited to determine H₂O₂. The resulting ECL biosensors showed a linear response to the concentration of H₂O₂ ranging from 1.0 × 10⁻⁸ to 6.6 × 10⁻⁴ mol L⁻¹ with a detection limit of 5 nmol L⁻¹ (S/N = 3) and good stability and reproducibility.     

The effect of cytosine on the two-step electroreduction of Zn ions in acetic buffers

Cytosine plays an important role in many biological processes since it constitutes the buildings blocks of DNA and RNA. A two-step reduction of Zn²⁺ ions at the dropping mercury electrode in acetic buffers at pH 4 and 5 in the presence of cytosine was examined. The measurements were performed using an impedance method in a wide potential and frequency ranges.The values of the standard rate constants k_s in the both studied system decrease from 3.8 × 10⁻³ to 2 × 10⁻³ cm s⁻¹ at pH 4 and from 5.1 × 10⁻³ to 2.5 × 10⁻³ cm s⁻¹ at pH 5. The values of the standard rate constants k_s1 characterizing the stage of the first electron transfer decrease similarly. However, the values of the standard rate constants k_s2 characterizing the stage of the second electron exchange decrease more markedly in the buffer at pH 4 than in the buffer at pH 5.     

Cathodic electrochemiluminescence behavior of norfloxacin/peroxydisulfate system in purely aqueous solution

A novel cathodic electrochemiluminescence (ECL) behavior of the norfloxacin (NFLX)/peroxydisulfate (S₂O₈²⁻) system in purely aqueous solution at a glassy carbon electrode (GCE) was firstly reported in this paper. The NFLX/S₂O₈²⁻ system could produce a very strong ECL signal under the potential scan from 0 to −1.8 V in 0.1 M phosphate buffer solution (pH 7.0) containing 0.24 mg/mL NFLX and 10 mM S₂O₈²⁻, which was about 350 times higher than that of S₂O₈²⁻ alone, while NFLX did not produce ECL in the absence of S₂O₈²⁻. The effects of pH value, S₂O₈²⁻ and NFLX concentration on the ECL intensity were investigated and the possible mechanism for the ECL behavior of NFLX/S₂O₈²⁻ system was proposed.     

Grain boundaries and the influence of the ionophilic-ionophobic balance on Li and F NMR and conductivity in low-dimensional polymer electrolytes with lithium tetrafluoroborate

⁷Li and ¹⁹F NMR linewidths and impedance spectra are reported for low-dimensional CmOn (I):LiBF₄ mixtures. Data for the ionophilic polymer C18O5 is compared with that for the ionophobic C18O1 and the block copolymer C16O1O5(21%) (21 mol% of C16O5). In C18O5:LiBF₄ (1:1) narrow ⁷Li linewidths, which were observed in the liquid crystal phase above the side chain melting temperature (∼50 °C), persist in the crystal down to ca. 0 °C and broaden below −20 °C. However, in C18O1:LiBF₄ (1:0.6) narrow ⁷Li linewidths were also observed down to −20 °C suggesting highly mobile neutral aggregates of salt since this system is non-conductive. In the copolymer C16O1O5(21%):LiBF₄ (1:0.7) the linewidths were even narrower down to −70 °C with weak temperature dependence. In all systems ¹⁹F linewidths were significantly broader than ⁷Li linewidths. The complex plane plots obtained by impedance spectroscopy exhibit characteristic minima identified with ‘grain boundary’ resistance and, following heat treatment, minima with weak temperature dependence identified with ‘internal crystal’ resistance, R_i, and conductivities, σ_i ≥ 10⁻⁴ S cm⁻¹. Four-component mixtures of copolymers CmO1O5 and CmO1O4 with LiBF₄ and ‘salt-bridge’ poly(tetramethylene oxide)-dodecamethylene copolymers gave conductivities of ca. 4 × 10⁻⁴ S cm⁻¹ at 20 °C with weak temperature dependence. A novel carrier-hopping mechanism of lithium transport decoupled from side chain melting in the crystalline state is postulated.      

Efficient green-colored electrochemiluminescence from cyclometalated iridium(III) complex

The spectroscopy, electrochemistry, and electrochemiluminescence (ECL) of cyclometalated iridium(III) bis(2-(p-tolyl)pyridinato-N, C^2′) (picolinate) [(tpy)₂Ir(pico)] was investigated. (tpy)₂Ir(pico) shows high photoluminescence efficiency (Φ_PL = ∼0.31) and quasi-reversible redox behaviors in acetonitrile solution. Intense green ECL was observed from all three modes of ECL generation (annihilation, oxidative-reduction, and reductive-oxidation). Relative ECL efficiencies with or without coreactants from (tpy)₂Ir(pico) were estimated using Ru(bpy)₃²⁺ (bpy, 2,2′-bipyridine) as a relative standard. Typically, in the reductive-oxidation process with peroxodisulfate (S₂O₈²⁻), (tpy)₂Ir(pico) produces 8-fold more efficient ECL at approximately 531 nm than Ru(bpy)₃². This efficient green ECL indicates potential for the development of multicolored ECL analysis in addition to standard Ru(bpy)₃²⁺ systems.     

Direct electrochemiluminescence of CdTe quantum dots based on room temperature ionic liquid film and high sensitivity sensing of gossypol

A new method with high sensitivity was developed to determine gossypol content using CdTe quantum dot (QD) electrochemiluminescence (ECL) with a room temperature ionic liquid (RTIL) modified glassy carbon (GC) electrode. It was found that use of RTIL film on the GC electrode can greatly enhance the ECL intensity of CdTe QDs, and the ECL peak potential and ECL onset potential were both shifted positively. Under optimal conditions, the quenching effect of gossypol on the ECL emission of CdTe QDs was observed, and ECL intensity showed a good linear relationship in the gossypol concentration range of 5.0 × 10⁻⁷ to 5.0 × 10⁻⁹ M with a detection limit of 5.0 × 10⁻⁹ M. The proposed method was used to detect gossypol in cottonseed oil with satisfactory results. As a result, the introduction of an RTIL-modified electrode can extend the analytical applications of QD ECL systems.