Electrochemiluminescence Substrate Research Articles

Construction of electrochemical and electrochemiluminescent dual-mode aptamer sensors based on ferrocene dual-functional signal probes for the sensitive detection of Alternariol

In this study, a novel dual-mode aptamer sensor was developed using Fca-DNA2 as the quenching electrochemiluminescence (ECL) and electrochemical (EC) signal response probe, and Ru-MOF/Cu@Au NPs were used as the ECL substrate platform to detect Alternariol (AOH) via a competitive reaction between AOH and Fca-DNA2. Compared with the conventional aptamer sensor with a single detection signal, this dual-mode aptamer sensor has the following advantages: (1) Electrodeposition-based rapid synthesis Ru-MOF on the electrode surface. (2) The Signal amplification substance Cu@Au NPs can synergistically catalyze Triethanolamine (TEOA) to amplify ECL behavior. (3) The aptamer sensor employs the dual-functional material Fca, which can detect both ECL and EC signals, increasing the result accuracy. Both ECL and EC methods have excellent detection performance for AOH in the detection range of 0.1 pg/mL to 100 ng/mL, with detection limits of 0.014 and 0.083 pg/mL, respectively, and are expected to be used for sensitive AOH detection in real samples.

Electrochemiluinescence monitoring the interaction between human serum albumin and amyloid-β peptide

Human serum albumin (HSA) is a major interaction-partner of amyloid-β (Aβ) peptide in the plasma and can modulate the aggregation of Aβ. In this work, an efficient smart electrochemiluminescence (ECL) sensing platform was applied to determine the ability of HSA to bind different Aβ40 aggregate species. Specifically, HSA was firstly adopted as a linker and self-assembled on the gold electrode, Aβ peptide were subsequently anchored onto the HSA-modified electrode through the recognition by HSA. CdS quantum dots (CdS QDs) modified with Aβ40 aptamer as the ECL substrate were then captured on the electrode via the specific coordination between Aβ40 and the aptamer. The present ECL sensor showed different ECL response in the presence of Aβ40 with different aggregation states. The ECL platform exhibited a signal-on response with the introduction of Aβ40 monomer in a concentration-dependent manner from 10 fM to 0.1 nM. Furthermore, the inhibition effect of several phenols on the aggregation of Aβ40 was also investigated. This work potentially provided a feasible strategy of sensing platforms for Aβ detection and further understanding of the mechanism by which HSA modulates the aggregation of Aβ.

Aptamer and Ru(bpy)32+‐AuNPs‐based electrochemiluminescence biosensor for accurate detecting Listeria monocytogenes

AbstractAs a widespread foodborne pathogen, Listeria monocytogenes (LM) can potentially cause a large number of food safety incidents, and the mortality rate of humans infected with this pathogen is relatively high. Thus, establishment of a fast and simple inspection technology is imperative. Herein, a solid‐state electrochemiluminescence (ECL) biosensing switch system based on special ferrocene‐labeled molecular beacon aptamer (Fc‐MBA) has been developed for rapid detection of LM. The biosensor consisted of two main parts, an ECL substrate and an ECL intensity switch. ECL substrate was generated by modifying the complex of gold nanoparticle (AuNPs) and ruthenium (II) tris‐(bipyridine) onto Au electrode, and an MBA labeled by Fc that acted as an ECL intensity switch. Moreover, in the presence of LM, the stem‐loop structure of MBA could be opened and the ferrocene was kept away from ECL substrate, which was due to an obvious ECL intensity increment. The limit of detection was 5 CFU/mL, and satisfactory recoveries of 98.1–103.6% were observed. Thus, we propose a novel method for accurate and specific detection of LM.

Highly sensitive electrochemiluminescence biosensor for VEGF165 detection based on a g-C3N4/PDDA/CdSe nanocomposite.

In this work, an electrochemiluminescence (ECL) biosensor was fabricated for the selective detection of vascular endothelial growth factor (VEGF165). g-C3N4/PDDA/CdSe nanocomposites were used as the ECL substrate. Then, DNA labeled at the 5' end with amino groups (DNA1) was immobilized on the surface of g-C3N4/PDDA/CdSe nanocomposite-modified glassy carbon electrode (GCE) by amido linkage. AuNP-labeled target DNA (Au-DNA2) could hybridize with DNA1 to form a double strand. The ECL of the g-C3N4/PDDA/CdSe nanocomposite was efficiently quenched due to the resonance energy transfer between CdSe QDs and Au NPs. After VEGF165 was recognized and bound by Au-DNA2, the double helix was disrupted, and the energy transfer was broken. In this case, Au-DNA2 was released from the electrode surface, and the ECL intensity recovered to a higher level. Under optimal conditions, this ECL biosensor possesses excellent selectivity, accuracy, and stability for VEGF165 detection in a linear range of 2pgmL-1 to 2ngmL-1 with a detection limit of 0.68pgmL-1. In addition, this assay has been successfully applied to the determination of VEGF165 in serum samples. Graphical abstract Schematic representation of the electrochemiluminescence sensor based on a g-C3N4/PDDA/CdSe nanocomposite, which can be determined in the concentration of vascular endothelial growth factor in serum.

Novel electrochemiluminescent platform based on gold nanoparticles functionalized Ti doped BiOBr for ultrasensitive immunosensing of NT-proBNP

Heart failure is a serious medical condition and has become one of the world’s biggest killers. N-terminal pro-B-type natriuretic peptide (NT-proBNP) has been recommended as a new biomarker of excellent prognosis-predictive ability for heart failure. Herein, a label-free electrochemiluminescence (ECL) immunosensor based on gold nanopariticles (Au NPs) functionalized Ti doped BiOBr (Ti:BiOBr-Au) is fabricated for the detection of NT-proBNP. Firstly, three-dimensional flower-like Ti doped BiOBr (Ti:BiOBr), which is firstly proposed with ECL property, is employed as both the ECL substrate and emitter to simplify the construction procedure. In the presence of K2S2O8, the formed Ti:BiOBr can generate stronger ECL signal than pure BiOBr. Due to the large specific surface area, Ti:BiOBr is functionalized with large amounts of Au NPs to further improve ECL emission. Under optimal experimental conditions, a linear response range for NT-proBNP detection from 0.001 ng mL−1 to 50 ng mL−1 is obtained with a detection limit of 0.33 pg mL−1. Featuring high sensitivity and excellent reproducibility, the proposed ECL immunosensor blazes a novel trail for the sensitive determination of NT-proBNP and other biomarkers. It is worth noting that Ti:BiOBr with stable ECL emission displays tremendous potential in ECL bioanalysis as a novel type of emitter candidates.

A novel solid-state Ru(bpy)32+ electrochemiluminescence immunosensor based on poly(ethylenimine) and polyamidoamine dendrimers as co-reactants

In this study, a novel solid-state Ru(bpy)32+ electrochemiluminescence (ECL) sandwiched immunosensor for sensitive detection of α-fetoprotein (AFP) was constructed based on poly(ethylenimine) (PEI) functionalized reduced graphene oxide (PEI-rGO) and Au nanoparticles (AuNPs) decorated polyamidoamine (PAMAM) dendrimers. Both PEI and PAMAM are polymers with a lot of amino groups, which are able to serve as good co-reactant to remarkably enhance the ECL signal of Ru(bpy)32+. For improving the poor conductivity of PAMAM, the AuNPs were decorated on the amino groups of PAMAM. Through Au-N bonds, the formed AuNPs-PAMAM was decorated on the PEI-rGO. The obtained AuNPs-PAMAM/PEI-rGO was introduced to immobilize the detection antibody (Ab2). Then, the Ab2 labeled AuNPs-PAMAM/PEI-rGO was modified onto the glass carbon electrode surface via sandwiched immunoreactions. The ECL substrate was prepared by mixing nafion and the complex (Ru-PtNPs) of Pt nanoparticles (PtNPs) and Ru(bpy)32+, which could reduce the consumption of Ru complex, simplify the operation and enhance the ECL efficiency. The experimental results demonstrated that the proposed immunosensor had good response to AFP. The linear range was from 0.01pgmL−1 to 10ngmL−1 with a low detection limit of 3.3fgmL−1. Meanwhile, with satisfying stability, selectivity and reproducibility, the proposed sandwiched immunosensor was presented to possess good potential in clinical detection.

The Enhanced Electrochemiluminescence of Luminol by Resonance Energy Transfer with Solid-phase CdTe Quantum Dots

Herein a new approach will be reported to enhance the electrochemiluminescence (ECL) of luminol by resonance energy transfer (ECRET) with solid-phase CdTe quantum dots (QDs) which were immobilized on the surface of indium tin oxide coated glass. This progressive result suggests a solid-phase ECL substrate which commenced more sensitive response upon luminol needless any co-reactant. Also the graphene oxide was applied to promote the performance of matrix. On this solid-phase ECL substrate, the detection limit of luminol decreased about one order of magnitude, meanwhile the practicable pH range was enlarged. Also it provides an excellent platform for H2O2 or oxygen monitoring due to they further intensified the ECL. The detection limit for H2O2 decreased two to three orders of magnitudes (to the level of 10−11M).

A sensitive signal-off aptasensor for adenosine triphosphate based on the quenching of Ru(bpy)32+-doped silica nanoparticles electrochemiluminescence by ferrocene

In this paper, a novel and sensitive signal-off electrochemiluminescence (ECL) aptasensor was proposed for the detection of adenosine triphosphate (ATP) on a nanoporous gold (NPG) modified glassy carbon electrode. The NPG was easily synthesized by a selective dissolution of silver from silver/gold alloy in nitric acid. The ECL aptasensor consisted of two main elements: an ECL substrate, made by modifying the amino group functionalized Ru(bpy)32+-doped silica (Ru-silica), and an ECL intensity switch, which contains two probes, split from one aptamer. The first probe (ssDNA1) was functionalized with a thiol group at one end and attached to Ru-silica through the linking agent of N-succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate. The other one (ssDNA2) is ferrocene-labeled probe, which was functionalized with ferrocene tag at the amino group functionalized end. We demonstrated that the ssDNA1/ATP/ssDNA2 sandwich composites layer could be formed in the presence of ATP, and lead to a quenching of Ru(bpy)32+. However, only a slight decrease could be observed in the absence of ATP. Under optimal conditions, the proposed biosensor provided a wide linear response range over 0.1pmolL−1–10.0nmolL−1 with a detection limit of 0.03pmolL−1.

An ultrasensitive electrochemiluminescence immunoassay based on supersandwich DNA structure amplification with histidine as a co-reactant

Here we report a novel electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of carcinoembryonic antigen (CEA) via histidine labeled supersandwich DNA structure to amplify the ECL signal. Histidine is an α-amino acid with an imidazole group, which can act as a co-reactant of tris(2,2′-bipyridyl) ruthenium(II) (Ru(bpy)32+) to amplify ECL signal. To the best of our knowledge, this is the first time to use histidine as co-reactant of Ru(bpy)32+ for signal amplification. The ECL substrate is fabricated by locating the complex of Pt nanoparticles (PtNPs) and Ru(bpy)32+ (Ru–PtNPs) on Nafion modified electrode surface. In the presence of antigens, the sandwiched immunocomplex can be formed between the primary antibodies on the ECL substrate and the secondary antibodies on the gold nanoparticles. The carried auxiliary probe I trigger a cascade of hybridization events between alternating auxiliary probe I and histidine-modified auxiliary probe II to form the long DNA concatamers. Thus the long DNA concatamers contain multiple histidine-modified auxiliary probe II, which accordingly achieve significant signal amplification. As a result, the sensitivity of proposed immunosensor for CEA detection is improved, the linear range is from 0.1pgmL−1 to 100ngmL−1 with a low detection limit of 33.3fgmL−1. Moreover, with the satisfying stability, selectivity and reproducibility, the proposed supersandwich immunoassay performs good promise in clinical detection.

Design of a Solid‐State Electrochemiluminescence Biosensor for Detection of PML/RARα Fusion Gene Using Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$‐AuNPs Aggregations on Gold Electrode

AbstractA solid‐state electrochemiluminescence (ECL) biosensor based on special ferrocene‐labeled molecular beacon (Fc‐MB) for highly sensitive detection of promyelocytic leukemia/retinoic acid receptor alpha (PML/RARα) fusion gene was developed successfully using Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$/2‐(dibutylamino)ethanol (DBAE) as detecting pattern. Such a special sensor involves two main parts, an ECL substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Ruthenium (II) tris‐(bipyridine) and Au nanoparticles (Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$‐AuNPs) onto the Au electrode (AuE) surface. The molecular beacon probe in which the ferrocene tag could effectively quench the ECL of the Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$acted as ECL intensity switch. The molecular beacon probe was designed with special base sequence, which could hybridize with its complementary target DNA. In the absence of a target, the hairpin structure of the probe forced the ferrocene (Fc) into close proximity with the ECL substrate, thus reducing ECL intensity. Target binding allowed the Fc away from the ECL substrate and resulted in an obvious increment in ECL intensity due to the decreased Fc quenching effect. The effect of the amount of Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ and the mixing procedure of Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ and AuNPs solution on the fabrication of ECL film had been investigated. As a result, the change of ECL intensity had a direct relationship with the logarithm of PML/RARα fusion gene concentration in the range of 0.05–500 pM with a detection limit of 7 fM, and the developed biosensor possessed good molecular recognizability in human serum. Thus, the approach holds promise for the early diagnostics and prognosis monitoring of APL and other diseases.

4-(Dimethylamino)butyric acid@PtNPs as enhancer for solid-state electrochemiluminescence aptasensor based on target-induced strand displacement

A solid-state electrochemiluminescence (ECL) aptasensor based on target-induced aptamer displacement for highly sensitive detection of thrombin was developed successfully using 4-(dimethylamino)butyric acid (DMBA)@PtNPs labeling as enhancer. Such a special aptasensor included three main parts: ECL substrate, ECL intensity amplification and target-induced aptamer displacement. The ECL substrate was made by modifying the complex of Pt nanoparticles (PtNPs) and tris(2,2-bipyridyl) ruthenium (II) (Ru(bpy)32+) (Ru–PtNPs) onto nafion@multi-walled carbon nanotubes (nafion@MWCNTs) modified electrode surface. A complementary thrombin aptamer labeled by DMBA@PtNPs (Aptamer II) acted as the ECL intensity amplification. The thrombin aptamer (TBA) was applied to hybridize with the labeled complementary thrombin aptamer, yielding a duplex complex of TBA–Aptamer II on the electrode surface. The introduction of thrombin triggered the displacement of Aptamer II from the self-assembled duplex into the solution and the association of inert protein thrombin on the electrode surface, decreasing the amount of DMBA@PtNPs and increasing the electron transfer resistance of the aptasensor and thus resulting large decrease in ECL signal. With the synergistic amplification of DMBA and PtNPs to Ru(bpy)32+ ECL, the aptasensor showed an enlarged ECL intensity change before and after the detection of thrombin. As a result, the change of ECL intensity has a direct relationship with the logarithm of thrombin concentration in the range of 0.001–30nM. The detection limit of the proposed aptasensor is 0.4pM. Thus, the approach is expected to open new opportunities for protein diagnostics in clinical as well as bioanalysis in general.

A solid-state electrochemiluminescence sensing platform for detection of adenosine based on ferrocene-labeled structure-switching signaling aptamer

A solid-state electrochemiluminescence sensing platform based on ferrocene-labeled structure-switching signaling aptamer (Fc-aptamer) for highly sensitive detection of small molecules is developed successfully using adenosine as a model analyte. Such special sensing platform included two main parts, an electrochemiluminescence (ECL) substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Au nanoparticle and Ruthenium (II) tris-(bipyridine) (Ru(bpy)(3)(2+)-AuNPs) onto Au electrode. An anti-adenosine aptamer labeled by ferrocene acted as the ECL intensity switch. A short complementary ssDNA for the aptamer was applied to hybridizing with the aptamer, yielding a double-stranded complex of the aptamer and the ssDNA on the electrode surface. The introduction of adenosine triggered structure switching of the aptamer. As a result, the ssDNA was forced to dissociate from the sensing platform. Such structural change of the aptamer resulted in an obvious ECL intensity decrease due to the increased quenching effect of Fc to the ECL substrate. The analytic results were sensitive and specific.

Detection of T4 DNA ligase using a solid-state electrochemiluminescence biosensing switch based on ferrocene-labeled molecular beacon

A solid-state electrochemiluminescence (ECL) biosensing switch based on special ferrocene-labeled molecular beacon (Fc-MB) has been successfully developed for T4 DNA ligase detection. Such special switch system consisted of two main parts, an ECL substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Au nanoparticle and Ruthenium (II) tris-(bipyridine) (Ru(bpy) 3 2+-AuNPs) onto Au electrode. A molecular beacon labeled by ferrocene as the ECL intensity switch. The molecular beacon is designed with special base sequence, which could combine with its target biomolecule via the reaction of the repair and recombination of nucleic acids by DNA ligase. During the reaction, the molecular beacon opened its stem–loop, and the labeled Fc was consequently kept away from the ECL substrate. Such structural change resulted in an obvious increment in ECL intensity due to the decreased Fc quenching effect to the ECL substrate. The analysis results are sensitive and specific.

A solid-state electrochemiluminescence biosensing switch for detection of thrombin based on ferrocene-labeled molecular beacon aptamer

A solid-state electrochemiluminescence (ECL) biosensing switch system based on special ferrocene-labeled molecular beacon aptamer (Fc-MBA) has been developed successfully for thrombin detections. Such special switch system includes two main parts, an ECL substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Au nanoparticle and Ruthenium (II) tris-(bipyridine) (Ru(bpy) 3 2+–AuNPs) onto Au electrode. A molecular beacon aptamer labeled by ferrocene acted as the ECL intensity switch. The loop bases of the ECL intensity switch are designed with special anti-thrombin aptamer sequence which could be combined with its target protein via the reaction between aptamer and thrombin. During the reactions, the molecular beacon aptamer opened its stem-loop, and the labeled Fc was consequently kept away from the ECL substrate. Such structural change resulted in an obvious ECL intensity increment due to the decreased quenching effect of Fc to the ECL substrate. The analytic results are sensitive and specific.