ECL Intensity Research Articles

Electrochemical Stability of Diphenylanthracene and Its Effect on Alternating‐Current‐Driven Blue‐Light Electrochemiluminescence Properties

AbstractElectrochemiluminescence (ECL) is a phenomenon in which light is emitted from excited species generated by electrochemical reactions at electrodes. Alternating‐current‐driven ECL (AC‐ECL) devices show good brightness and fast ECL response in comparison to direct‐current‐driven ECL devices. In this report, we focus on the ECL intensity and long‐term stability of blue‐light‐emitting AC‐ECL systems. We used a mixed solvent of propylene carbonate and toluene (volume ratio=1 : 1) to achieve stable blue ECL from 9,10‐diphenylanthracene (DPA) molecules. We analyzed the electrochemical, optical, and AC‐ECL properties of DPA in this mixed solvent to investigate the effect of the stabilities of redox species on AC‐ECL properties. We found that the composition of the electrolyte solution affects the stability of these species. We conclude that stability of generated active species is required to achieve good performance in blue AC‐ECL devices.

Electrochemiluminescent graphene quantum dots enhanced by MoS2 as sensing platform: a novel molecularly imprinted electrochemiluminescence sensor for 2-methyl-4-chlorophenoxyacetic acid assay

The ECL properties and application of a novel luminescent material molybdenum disulfide-graphene quantum dots (MoS2-GQDs) hybrid nanocomposite was reported for the first time. The hybridization of MoS2 and GQDs endowed nanocomposite with structural and compositional advantages for boosting the ECL performance of GQDs. Impressively, the ECL could be remarkable enhanced using MoS2-GQDs hybrid nanocomposite, which was ∼13, ∼185 and ∼596-folds larger than the ECL intensity of GQDs, MoS2 modified electrodes and bare electrode, respectively. Subsequently, as a sensing platform, the MoS2-GQDs hybrid nanocomposite was applied to fabricate molecularly imprinted electrochemiluminescence sensor for the ultrasensitive and selective determination of 2-methyl-4-chlorophenoxyacetic acid. Under optimal conditions, the detection limit of the prepared sensor was 5.5pmolL−1 (S/N=3) within a linear concentration range of 10pmolL−1–0.1μmolL−1. The developped sensor exhibited high sensitivity, good selectivity, reproducibility and stability, suggesting the potential for detecting pesticides and veterinary drugs at trace levels in food safety and environmental control.

DNA nanomachine-based regenerated sensing platform: a novel electrochemiluminescence resonance energy transfer strategy for ultra-high sensitive detection of microRNA from cancer cells.

The construction of DNA nanomachines holds great significance in the development of DNA nanostructures; however, the real application of nanomachines is still in its early stage. Moreover, one-step regenerated sensing platforms for the detection of biomarkers in the current research remain a practical challenge. Herein, a novel electrochemiluminescence resonance energy transfer (ERET) strategy between Alexa Flour 488 (AF 488), which is a type of small molecule dye, as the donor and CdSe@ZnS quantum dots (QDs) as the acceptor, which easily enter the cells, has been reported and was applied for the construction of a DNA nanomachine-based regenerated biosensor for the ultra-high sensitive determination of cancer cells without any enzyme. First, a dual amplification strategy, including target recycling and signal transformation, was employed to achieve the conversion of a small number of miRNAs into a large amount of universal DNA reporters. Initially, the DNA tweezer was kept in the "off" state with two arms labeled with QDs and AF488, respectively. Second, in the presence of DNA reporters, the tweezer transformed to the "on" state through the hybridization of the reporter DNA and exposed the arms of the tweezer. Simultaneously, QDs and AF488 on the two arms were close enough to generate ERET, which remarkably increased the ECL intensity of the QDs. Impressively, the sensor could be regenerated by a one-step strand displacement and could be cycled for more than seven times. Owing to the dual amplification strategy and the high efficiency of the ERET between the QDs and AF488, the proposed biosensor performs in the linear range from 10 pM to 0.1 fM with a detection limit of 0.03 fM for miRNA determination, and the monitoring of different cancer cells was also achieved. Moreover, the elaborated biosensor can also realize the sensitive detection of Pb2+, which indicates that it can be potentially used for field environmental analysis and monitoring, thus offering a new modular platform for the construction of functional DNA nanomachines in the ultra-high sensitive analysis of promising biomarkers and toxic metals.

A sandwich electrochemiluminescent biosensor based on enzymatic reaction to in situ generate coreactant of conjugated polymer for Con A detection

A novel “signal-on” biosensor for the detection of concanavalin A (Con A) was designed utilizing an enzymatic reaction to in situ generate coreactant of poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO). Firstly, PFO polymers were wrapped with graphene oxide nanosheets to obtain GO@PFO nanocomposite, which was modified onto the surface of the electrode as a matrix for immobilizing phenoxy-derivatized dextran (Dexp) through π-π stacking interaction. Then Con A interacted with Dexp through the specific carbohydrate-protein interaction. Finally, glucose oxidase (GOx) and lactate oxidase (LOx) decorated gold nanoparticles@C60-Polyamidoamine (Au@C60-PAMAM) was bound onto Con A via a biospecific interaction between Con A and the internal residues of GOx, thus achieving a sandwich structure. In this construction strategy, LOx catalyzed the oxidation of lactate to in situ generate H2O2, which could act as the coreactant of PFO to enhance the ECL intensity. Due to the excellent ECL property of PFO–H2O2 system, our prepared biosensor showed a wide linear range from 0.001ng/mL to 10ng/mL, and a low detection limit down to 0.0003ng/mL. The integration of excellent ECL property of PFO–H2O2 system and excellent catalytic activity of Au@C60-PAMAM would open a new and promising platform for fabricating ECL biosensors and biocatalysts.

Sensitive electrochemiluminescence resonance energy transfer (ECL-RET) between Ru(bpy) 3 2+ and Au nanorod for hydrogen peroxide detection

Here, we developed a novel electrochemiluminescence resonance energy transfer (ECL-RET) approach between Ru(bpy)32+ and Au nanorods (NRs) for sensitive determination of H2O2. Au NRs were synthesized through silver ion-assisted seed-mediated method which exhibited an obvious absorption peak at about 627 nm. They were modified at glassy carbon electrode (GCE) surface which showed a significant ECL quenching efficiency about 56.5% due to the ECL-RET process. This Au NRs modified electrode was then utilized to measure the concentration of H2O2 on the basis of the significant quenching effect of H2O2 on Ru(bpy)32+ ECL. Results demonstrated that the decrement of ECL intensity at Au NRs modified electrode had ~ 6.6-fold enhancement as compared with that at bare electrode.

Dual-signal amplification strategy for electrochemiluminescence sandwich biosensor for detection of thrombin

In the present study, the authors report a novel sandwich biosensor for detection of thrombin using electrochemiluminescence method based on dual-signal amplification strategy. Firstly, the gold nanoparticles graphene composite (GNPs-graphene) was obtained by simultaneously depositing the chloroauric (III) acid tetrahydrate [HAuCl4·4H2O] and graphene solution with a cyclic voltammetry. Secondly, one thiol-modified thrombin aptamer (TBA1) was immobilized the glassy carbon electrode (GCE) via Au-S bonding. And then the other thiol-modified biotinylated thrombin aptamer (TBA2) that were modified with Ru(bpy)32+ were anchored on the surface of the gold nanoparticles in solution. This proposed assay took dual signal amplification strategies. On the one hand, a single gold nanoparticle can connect many TBA2 to come into being a signal cluster (Ru-TBA2-AuNPs), thus when a little thrombin were present the system the ECL intensity will have a strong signal response; On the other hand, the GNPs-graphene can promote the electron transfer efficiency and increase the signal response. The ECL signal had a good linear relationship with thrombin concentration in range of 0.01–10nM, and the detection limit for thrombin was determined to be as low as 6.3 pM. This biosensor also showed good selectivity for thrombin without being affected by some other proteins, such as BSA and lysozyme and so on. Moreover, this proposed method was successfully applied to thrombin analysis in diluted human serum samples.

New Software for Simulation of Electrochemical Reaction Mechanisms of Any Complexity

We introduce here our scientific software KISSA designed for automatic simulation of electrochemical reaction mechanisms of any complexity, including those leading to ECL emission at planar, (hemi)spherical and (hemi)cylindrical working electrodes (KISSA-1D) as well as at microelectrodes such as disk or band (KISSA-2D). Simulations are performed by KISSA using a novel approach [1, 2] developed by the authors which involves conformal coordinate transformations to overcome the numerical difficulties arising from diffusional propagation of species and automatic grid adaptation based on the detection of large kinetic terms to obtain accurate results for both concentrations and electrochemical currents even in the presence of steep concentration gradients. This approach allows for efficient resolution of all physicochemical and mathematical issues connected both with edge effects (nano- and microelectrodes) and considerable disparity of time and length scales of the underlying processes arising due to quickly changing electrode potential and/or extremely rapid homogeneous chemical reactions for any complex mechanisms. The software offers a possibility to take into account spontaneous natural convection which limits the extent of the diffusion layer and leads to the establishment of a steady state current even at macroelectrodes. Furthermore, this enables setting correct and thermodynamically consistent initial conditions within the stagnant layer when the system is pre-equilibrated at a given rest potential for a finite period of time [3]. The software also allows simulating complex adsorption dynamics, i.e., kinetics and chemical reactions involving surface-bound species [4, 5]. The programs offer convenient entry of a reaction mechanism and parameters and provide access to the computed dynamic spatial distributions of all important quantities such as currents and current densities, concentration distributions of all reactants, surface coverage of adsorbed species [4, 5] as well as ECL intensity [6] (if applicable) through a graphical user interface [7]. [1] C. Amatore, O.V. Klymenko, I. Svir, Electrochem. Commun. 12 (2010) 1170. [2] O.V. Klymenko, I. Svir, A. Oleinick, C. Amatore, ChemPhysChem 13 (2012) 845. [3] C. Amatore, O.V. Klymenko, I. Svir, Anal. Chem. 84 (2012) 2792. [4] O.V. Klymenko, I. Svir, C. Amatore, J. Electroanal. Chem. 688 (2013) 320. [5] O.V. Klymenko, I. Svir, C. Amatore, Molecular Physics, 112 (2014) 1273. [6] O.V. Klymenko, I. Svir, C. Amatore, ChemPhysChem, 14 (2013) 2237. [7] http://kissagroup.com/index.php/bibliography

A bifunctional catalyst based ECL immunosensor for a cardiac biomarker regulated by oxygen evolution reaction

Prostaglandin E1, a cardiac biomarker, is a pivotal member of the prostaglandin family which exerts diverse and powerful effects on cell function in many organ systems. In this study, a new approach for the ultrasensitive determination of prostaglandin E1 was proposed by using the ECL of peroxydisulfate with oxygen as coreactant. Compared to most peroxydisulfate ECL sensor, this proposed ECL strategy propounded employing oxygen evolution reaction to enhance the concentration of oxygen, which was unprecedented in ECL sensing platform. Herein, ultrathin NiCo2O4 nanosheets with large surface area and mesoporous structure were prepared by a facile method, and adamantane as enhancer was decorated on the surface of amino-modified NiCo2O4 to generate a bifunctional catalyst of NiCo2O4@AD(Prostaglandin E), which possessed excellent catalytic performance toward the oxygen evolution reaction. Accordingly, the sensitivity of ECL immunosensor was enhanced with the increasing concentration of oxygen by the bifunctional catalyst of NiCo2O4@AD. And the ECL response of the peroxydisulfate would decrease owing to the interaction between antibody and antigen on the modified electrode. Consequently, on the basis of the ECL intensity change of peroxydisulfate, the proposed immunosensor has realized ultrasensitive PGE1 assay with a wide linear detection range of 0.1fg/ml to1ng/ml and a detection limit of 0.1fg/ml. The proposed ECL immunosensor was performed to analyze prostaglandin E1 in human serum, and satisfactory recoveries were obtained, indicating its potential applications in clinical diagnostics.

Nitrogen doped graphene quantum dots based single-luminophor generated dual-potential electrochemiluminescence system for ratiometric sensing of Co2+ ion

Herein, a single luminophor dual-potential chemiluminescence (ECL) system based on nitrogen doped graphene quantum dots (NGQDs) was developed for ratiometric detection of Co2+ ion. Dissolved oxygen is changed to O2− and HO2− which participate in the anodic and cathodic ECL generating processes of NGQDs. Co2+ ion was demonstrated able to evidently amplify the anodic intensity by displaying catalytic action of the intermediate steps of anodic ECL reactions, and quench the cathodic ECL intensity because of the effective elimination on excited states (NGQDs*) generating. Hence, the target Co2+ ion could be quantified by the ratio of ECL intensities at two excitation potentials. On this basis, without any labeling and additional coreactants, an accurate and reliable sensing system based on the dual-potential ECL of NGQDs toward Co2+ ion was fabricated with excellent sensitivity and selectivity against other interferential metal ions. The developed ratiometric sensor exhibited a linear response ranging from 1.0μM to 70μM with a limit of detection of 0.2μM (S/N=3). The proposed dual-potential ratiometric NGQDs based ECL sensor was also used to detect Co2+ ion in real water samples. As single luminophor, NGQDs possessing multiple-ECL signals is simple without labeling, providing more reliable signals in sensing than other essential state dependent techniques.

Novel graphene/Au-CdS:Eu composite-based electrochemiluminescence immunosensor for cancer biomarker detection by coupling resonance energy transfer and enzyme catalytic reaction

Recent studies show that ECL resonance energy transfer (ECL-RET) coupled with H2O2-related enzymatic reactions is an efficient strategy for designing excellent ECL biosensors with high sensitivity. Here we find that a ternary composite named graphene/Au-CdS:Eu QDs demonstrated ECL-RET effect with Au nanorods (Au NRs) and horseradish peroxidase (HRP) on the Au NRs could catalyze hydrogen peroxide reduction in the presence of hydroquinone (HQ). Therefore, we developed an efficient dual-quenching ECL immunosensor based on the novel ternary composite with high ECL intensity coupled with H2O2-related enzymatic reactions and ECL-RET strategy from Au NRs. This ultrasensitive ECL sensing strategy combined the advantages of the excellent ECL sensing properties of graphene/Au-CdS:Eu QDs, and dual-quenching effect and achieve sensitive detection of alpha fetoprotein (AFP).

Turn-on near-infrared electrochemiluminescence sensing of thrombin based on resonance energy transfer between CdTe/CdS coresmall/shellthick quantum dots and gold nanorods

Here we designed a near-infrared electrochemiluminescence (NECL) aptasensor for turn-on ultrasensitive determination of thrombin. It was based on the ECL resonance energy transfer (ECL-RET) of CdTe/CdS coresmall/shellthick quantum dots (QDs) to gold nanorods (AuNRs). AuNRs which functioned as ECL acceptors were assembled onto CdTe/CdS film by DNA hybridization between aptamers and their complementary oligonucleotides. In the absence of thrombin, the NECL of QDs was quenched as a result of the ECL-RET of QDs to AuNRs. In the presence of thrombin, the NECL of the system was “turned on” because thrombin can replace the AuNRs onto the QDs film, owing to the specific aptamer-protein affinity interactions. In this way, the increment of ECL intensity and the concentration of thrombin showed a logarithmic linear correlation in the range of 100 aM to 10 fM with a detection limit of 31 aM (S/N=3). Importantly, the developed aptasensor was successfully applied to thrombin sensing in real serum samples.

A paper-based electrochemiluminescence electrode as an aptamer-based cytosensor using PtNi@carbon dots as nanolabels for detection of cancer cells and for in-situ screening of anticancer drugs

A paper-based portable and disposable cyto-device was fabricated for the purpose of detecting cancer cells and in-situ screening of anticancer drugs. The device was prepared as follows: (a) Au@Pd paper electrodes were prepared by growing Au@Pd nanoparticles on cellulose; (b) the aptamer against MCF-7 cells was immobilized on the paper electrodes; (c) PtNi alloy particles were loaded with carbon dots to form a PtNi@C-dot composite acting as the ECL label, (d) concanavalin A (Con A) was labeled with the ECL label and then dropped on sensor surface carrying cancer cell. Con A can specifically recognize the mannose on the cancer cell surface. The assay is performed in the following way: (1) The aptamer-modified electrode is placed in a solution containing MCF-7 cancer cells; (2) buffer containing peroxodisulfate is added; (3) a potential sweep (from −0.5 to −1.8 V) is applied to the electrode, and ECL intensity is recorded. ECL intensity is related to the number of captured MCF-7 cells in the 480 to 2.0 × 107 cells⋅mL‾1 concentration range. The electrode was applied to design a screening method for anti-cancer drugs. This is accomplished by monitoring the number of apoptotic cancer cells after exposing the cells on the electrode to a drug-containing medium. In our perception, the method presented here has a wide range of potential applications in cancer diagnosis and treatment.

Simple and sensitive electrogenerated chemiluminescence peptide-based biosensor for detection of matrix metalloproteinase 2 released from living cells.

A simple and sensitive electrogenerated chemiluminescence biosensor was developed to monitor matrix metalloproteinase 2 (MMP-2) by employing a specific peptide (CGPLGVRGK) as a molecular recognition substrate. Bis(2,2'-bipyridine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester-bis(hexafluorophosphate) (Ru(bpy)2(mcbpy-O-Su-ester)(PF6)2 (Ru1) was used as ECL-emitting species and covalently labeled onto the peptide through NH2-containing lysine on the peptide via acylation reaction to form Ru1-peptide as an ECL probe. An ECL peptide-based biosensor was fabricated by self-assembling the ECL probe onto the surface of gold electrode. MMP-2 can specifically cleave the Ru1-peptide on the electrode surface, which led the partly Ru1-peptide to leave the electrode surface and resulted in the decrease of the ECL intensity obtained from the resulted electrode in 0.1M phosphate-buffered saline (pH7.4) containing tri-n-propylamine. The decreased ECL intensity was piecewise linear to the concentration of MMP-2 in the range from 1 to 500ng/mL. Moreover, the ECL biosensor is successfully applied to detection of MMP-2 secreted by living cell, such as HeLa cells. Additionally, the biosensor was also applied to the evaluation of matrix metalloproteinase inhibitors. The strategy presented here is promising for other disease-related matrix metalloproteinase assay and matrix metalloproteinase inhibitor profiling with sensitivity and simplicity. Graphical Abstract Detection of MMP-2 released from living cells by ECL peptide-based biosensor.

Nonenzymatic electrochemiluminescence glucose sensor based on quenching effect on luminol using attapulgite–TiO2

A new nonenzymatic glucose ECL sensor based on attapulgite (Att) integrated with semiconductor material TiO2 was developed. The prepared material was characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Based on ECL experimental results, Att–TiO2 composites were found to be able to improve the ECL properties of luminol. When glucose is added into the system, TiO2 NPs serve as a catalyst and dissolved O2 acts as a cosubstrate for the glucose oxidation reaction. Dissolved O2 also worked as coreactant for the luminol ECL emission. Due to the consumption of dissolved O2, a quenching effect would appear on the luminol ECL emission. Under the optimized conditions, the linear logarithmic relationship between ECL intensity and the concentration of glucose was valid in the range from 1.0mM to 1.0nM (R=0.9976) with a detection limit (S/N=3) of 10.0pM. In addition, the proposed sensor presented good reproducibility, stability, and sensitivity for glucose detection and can be successfully applied in the determination of glucose in real blood samples.

Label-free Electrochemiluminescent Immunosensor for Detection of Prostate Specific Antigen based on Aminated Graphene Quantum Dots and Carboxyl Graphene Quantum Dots.

Prostate-specific antigen (PSA) was used as the model, an ultrasensitive label-free electrochemiluminescent immunosensor was developed based on graphene quantum dots. Au/Ag-rGO was sythsized and used as electrode material to load a great deal of graphene quantum dots due to the large surface area and excellent electron conductivity. After aminated graphene quantum dots and acarboxyl graphene quantum dots were modified onto the electrode, the ECL intensity was much high using K2S2O8 as coreactant. Then, antibody of PSA was immobilized on the surface of modified electrode surface through the adsorption of Au/Ag toward proteins, leading to the decrease of the ECL intensity. As proven by ECL spectra test and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the ECL intensity decreased linearly with the logarithm of PSA concentration in the range of 1 pg/mL ~ 10 ng/mL. The detection limit achieved is 0.29 pg/mL. The immunosensor results were validated through the detection of PSA in serum samples with satisfactory results. Due to excellent stability, high sensitivity, acceptable repeatability and selectivity, the immunosensor has promising applications in disease and drug analysis.

Sensitive and versatile electrogenerated chemiluminescence biosensing platform for protein kinase based on Ru(bpy)32+ functionalized gold nanoparticles mediated signal transduction

A novel, sensitive and versatile electrogenerated chemiluminescence biosensing platform is developed for monitoring activity and inhibition of protein kinase based on Ru(bpy)32+ functionalized gold nanoparticles (Ru(bpy)32+-AuNPs) mediated signal transduction. Ru(bpy)32+-AuNPs were formed by functionalizing AuNPs with Ru(bpy)32+ through electrostatic interactions and were used as thiol-versatile signal probe. Casein kinase II (CK2) and cAMP-dependent protein kinase (PKA), two classical protein kinase implicated in disease, were chosen as model protein kinases while a CK2-specific peptide (CRRRADDSDDDDD) and a PKA-specific peptide (CLRRASLG) were employed as molecular substrate for CK2 and PKA, respectively. The specific peptide was self-assembled onto the gold electrode via Au–S bond to form ECL biosensor. Upon thiophosphorylation of the peptide on the electrode in the presence of protein kinase and co-substrate adenosine-5’-(γ-thio)-triphosphate, Ru(bpy)32+-AuNPs was assembled onto the thiophosphorylated peptides via Au–S bond. The Ru(bpy)32+-AuNPs attached on electrode surface produce detectable ECL signal in the presence of coreactant tripropylamine. This strategy is promising for multiple protein kinase assay and kinase inhibitor profiling with high sensitivity, good selectivity and versatility. The ECL intensity is proportional to the activity of CK2 in the range of 0.01–0.5 unit/mL with a low detection limit of 0.008 unit/mL and to the activity of PKA in the range of 0.01–0.4 unit/mL with a detection limit of 0.005 unit/mL. Additionally, this assay was applied to the detection of CK2 in serum samples and the inhibition of CK2 and PKA. This work demonstrates that the developed ECL method can provide a sensitive and versatile platform for the detection of kinase activity and drug-screening.

Capillary electrophoresis with end-column electrochemiluminescence for ultrasensitive determination of urapidil hydrochloride in rat plasma and its application to pharmacokinetics study.

A simple, sensitive and selective method for determination of urapidil hydrochloride was developed using capillary electrophoresis with electrochemiluminescence (CE-ECL) technique for the first time. Under the optimized experimental conditions, the ECL intensity was linear with the concentration of urapidil hydrochloride in the range from 0.050 to 50.0ng/mL and the detection limit was 0.014ng/mL (S/N=3). The proposed method was used for studying pharmacokinetics of urapidil hydrochloride in rat plasma and the main pharmacokinetic parameters of the peak concentration (Cmax), half life time (T1/2) and peak concentration time (Tmax) were 240.45±21.15ng/mL, 0.58±0.16h and 1.08±0.13h, respectively. The recoveries of urapidil hydrochloride in the diluted extracts of rat plasma samples ranged from 96.68 to 98.82%. The RSD was lower than 3%.

A novel sandwich electrochemiluminescence immunosensor for ultrasensitive detection of carbohydrate antigen 19-9 based on immobilizing luminol on Ag@BSA core/shell microspheres.

A novel sandwich-type electrochemiluminescence immunosensor based on immobilizing luminol on Ag@BSA core/shell microspheres (Ag@BSA-luminol) for ultrasensitive detection of tumor marker carbohydrate antigen 19-9 (CA19-9) has been developed. Herein, magnetic carbon nanotubes (MAGCNTs) decorated with polyethylenimine (PEI) was used to construct the base of the immunosensor. MAGCNTs with prominent electrical conductivity and high surface area could be beneficial for promoting the electron transfer and loading plenty of primary antibodies (Ab1) via glutaraldehyde (GA). Meanwhile, the magnetic property of MAGCNTs makes it easy to be attached to the surface of magnetic glass carbon electrode (MGCE) through magnetism interaction, which provides an outstanding platform for this immunosensor. Moreover, Ag@BSA microspheres with large surface area, good stability, and excellent biocompatibility were desirable candidates for effective cross-link of CA19-9 detection antibodies (Ab2). A more interesting thing was that ELISA color reaction was used as an ultrasensitive strategy for identifying Ab2 was successfully coated on Ag@BSA with the naked eye. Additionally, we immobilized the luminol on the surface of Ag@BSA to prepare the target immunosensor. Immobilization of luminol on the surface of Ag@BSA could decrease the distance between luminophores and the electrode surface, leading to great enhancement of the ECL intensity of luminol in the present of hydrogen peroxide (H2O2). Under the optimal conditions, the intensity of the ECL immunosensor increased linearly with the logarithm of CA19-9 concentration in a wide linear range from 0.0005 to 150UmL(-1) with a detection limit of 0.0002UmL(-1) (S/N=3). All the results suggested the prepared CA19-9 immunosensor displayed high sensitivity, excellent stability and good specificity. The developed method opened a new avenue to clinical bioassay.

A novel electrochemiluminescence resonance energy transfer system for ultrasensitive detection of prostate-specific antigen

A novel electrochemiluminescence resonance energy transfer (ECL-RET) system from Eu3 +-doped CdS nanocrystals (CdS:Eu NCs) to Ru(bpy)32 +-doped silica nanoparticle (RuSi) was designed for ultrasensitive detection of prostate-specific antigen (PSA). The platform consists of a CdS:Eu NCs film on glassy carbon electrode (GCE) as ECL emitter and a sandwich-type immunocomplex formed by the primary antibody, PSA and RuSi-tagged second antibody. This system showed a maximum of 4.83-fold enhancement of ECL intensity at 620 nm due to the efficient ECL-RET and high Ru(bpy)32 + quantum yields. By the signal amplification of RuSi and the specific antibody–antigen interactions, this ECL-RET system could sensitively respond down to 1.0 fg mL− 1 PSA.

Novel preparation and electrochemiluminescence application of luminol functional-Au nanoclusters for ALP determination

Luminol functional Au nanoclusters (lum-AuNCs) were rapidly prepared in luminol–pepsin alkaline solution. Compared with the individual luminol, AuNCs and the mixture of luminol and AuNCs, the composite of lum-AuNCs had special ECL properties, which caused ca. 100-folds enhancement than the ECL intensity of the mixture. The possible mechanism for the preparation was discussed and the ECL properties of lum-AuNCs were given. The ECL intensity of lum-AuNCs could be inhibited effectively by phenol, which was the catalyzed product of phenyl phosphate disodium (PPNa) under the control of the alkaline phosphatase (ALP). Therefore, an anodic ALP-responsive ECL biosensor was constructed. Under the optimized conditions, the decrement of ECL intensity was linearly correlated to the ALP concentration in the range from 0.3 to 12.0nmolL−1 with a detection limit of 0.1nmolL−1. The as-proposed ALP biosensor exhibited high specificity and good stability. Finally, it was used to determining the concentration of ALP in human serums successfully.