Signal-on Electrochemiluminescence Research Articles

Highly Sensitive Electrochemiluminescence Biosensing Method for SARS-CoV-2 N Protein Incorporating the Micelle Probes of Quantum Dots and Dibenzoyl Peroxide Using the Screen-Printed Carbon Electrode Modified with a Carboxyl-Functionalized Graphene.

Obtaining stable electrochemiluminescence (ECL) emissions from a hydrophobic luminophore in aqueous solutions and designing a method without the use of an exogenous coreactant are promising for ECL biosensing. Here, a highly sensitive signal-on ECL immunoassay for the SARS-CoV-2 N protein was developed using micelles as an ECL tag. The micelles were prepared by coencapsulating the luminophore hydrophobic CdSe/ZnS quantum dots and coreactant dibenzoyl peroxide within the hydrophobic core of micelles. The ECL probe was obtained by covalently bonding a SARS-CoV-2 N protein-binding aptamer onto the micelle surface. The construction of the immunosensor was initiated by the immobilization of the anti-SARS-CoV-2 N protein antibody onto the screen-printed carbon electrode (SPCE) with a -COOH-functionalized surface. The surface functionalization of SPCEs was achieved through paste-exfoliated graphene, which was modified with a -COOH group through supramolecular-covalent scaffolds on SPCE. Upon achieving sandwich complexes on the immunosensor, an efficient ECL signal response at -1.4 V versus Ag/AgCl was obtained in phosphate buffer solution. The ECL assay was used for the sensitive determination of SARS-CoV-2 N protein with the linear range from 0.01 to 50 ng mL-1, and the detection limit was 3.0 pg mL-1. The immunosensor showed good reproducibility and stability, and the ECL immunoassay was used to determine the SARS-CoV-2 N protein in serum samples. The proposed approach to obtain micelles is versatile for the preparation of stable ECL luminophores by using hydrophobic materials, and the strategy provides an alternative for ECL bioassays based on the coreactant route.

Strong aggregation-induced electrochemiluminescence of pyrene-coordination metal-organic frameworks coupled with zero-valent iron as novel accelerator for ultrasensitive immunoassay

Polycyclic aromatic hydrocarbons (PAHs) are excellent alternative luminophores for electrochemiluminescence (ECL) immunoassays. However, they are inevitably limited by the aggregation-caused quenching effect. In this study, aimed at eliminating the aggregation quenching of PAHs, luminescent metal–organic frameworks (MOFs) with 1,3,6,8-tetra(4-carboxybenzene)pyrene (H4TBAPy) as the ligand were exploited as a novel nano-emitter for the construction of ECL immunoassays. The luminophore exhibits efficient aggregation-induced emission enhancement, good acid-base resistance property and unusual ECL reactivity. In addition, the simultaneous use of potassium persulfate and hydrogen peroxide as dual co-reactants resulted in a synergistic enhancement of the cathodic ECL efficiency. The use of magnetic iron-nickel alloys as the multifunctional sensing platform can further enhance the ECL activity, and its enriched zero-valent iron as a co-reactant accelerator effectively drives ECL analytical performance. Profiting from the excellent characteristics, signal-on ECL immunoassays have been constructed. With carcinoembryonic antigen as the model analysis target, a detection limit of 0.63 pg/mL was obtained within the linear range of 1 pg/mL to 50 ng/mL, accompanied by excellent analytical performance. This report opens a new window for the rational design of efficient ECL illuminators, and the proposed ECL immunoassays may find promising applications in the detection of disease markers.

Aggregation-induced enhancement of pyrene-based metal-organic framework as a new electrochemiluminescence emitter for ultrasensitive detection of sulfadimethoxine

In this study, a signal-on electrochemiluminescence (ECL) aptasensor for ultrasensitive detection of sulfadimethoxine (SDM) was constructed based on a competitive aptamer strategy. Specifically, cerium-metal-organic framework (Ce-MOF) with large specific surface area and excellent electrical conductivity was combined with gold nanoparticles (AuNPs) to form a substrate, followed by the immobilisation of double-stranded DNA (dsDNA) via AuN bonds. In the presence of SDM, the aptamer tended to form an aptamer-SDM complex, which caused dsDNA to dissociate. After release of the aptamer, the capture probe (CP) combined with the tracer label to enhance the ECL signal. As expected, the prepared sensor displayed an ideal linear response range from 10.0 fg mL−1 to 100 ng mL−1 with a limit of detection (LOD) of 1.28 fg mL−1 and successfully detected SDM in milk and quality control samples.

Encapsulation of Tetraphenylethylene Derivative in Liposome Vesicles as Promising Aggregation-Induced Electrochemiluminescence Emitter for Detection of Human Epidermal Growth Factor Receptor 2.

In this work, a sensitive signal-on electrochemiluminescence biosensor using liposome-encapsuled 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE) as a promising aggregation-induced electrochemiluminescence (AIECL) emitter for detection of biomarkers was developed. Aggregation-induced enhancement occurs internally through the spatial confinement effect and intramolecular self-encapsulation of encapsulating TPE and triethylamine (TEA) molecules in liposome cavities. Peptide sequence WTGWCLNPEESTWGFCTGSF (WF-20) was used to replace the antibody for reducing the steric hindrance of the sensing surface while taking into account the affinity. The proposed sensing strategies showed satisfactory properties for detection of human epidermal growth factor receptor 2 (HER2) ranging from 0.01 to 500 ng/mL with a limit of detection of 6.65 pg/mL. The results confirmed that encapsulation of luminescent molecules in the vesicle structure for triggering the AIECL phenomenon is a promising method to prepare a signal label for a trace detection biomarker.

A signal-on electrochemiluminescence immunosensor for A2780 cell detection based on the excellent catalytic performance of Co2+ doped TiO2 nanodisks

A selective and sensitive A2780 cell analysis platform was established.

A Novel Signal-On Electrochemiluminescence Immunosensor for the Detection of NSCLC Antigen Biomarker Based on New Co-Reaction Accelerators.

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer with substantial morbidity and mortality. Herein, a new signal-on electrochemiluminescence (ECL) immunosensor based on multiple amplification strategies is constructed for ultrasensitive detection of cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) biomarker related to NSCLC. Polyethyleneimine (PEI) functionalized MXene is decorated with NiMn layer double hydroxide (NiMn LDH) to form MXene-PEI-NiMn LDH composite. Specially, the La-MOF@ZIF-67 bimetallic organic framework (named as LZBM) and MXene-PEI-NiMn LDH both served as coreaction accelerators to improve the ECL emission of the luminol-H2 O2 system. To be specific, Au nanoparticles (AuNPs) coated MXene-PEI-NiMn LDH is applied to immobilize primary CYFRA21-1 antibody (Ab1 ), while AuNPs decorated LZBM was used for the loading of luminol and secondary CYFRA21-1 antibody (Ab2 ) to form tracer label. Therefore, the ECL signal of the sandwich-type immunosensor is significantly enhanced due to the high loading capability for luminol and the synergistic catalytic ability for the decomposition of H2 O2 into reactive oxygen species (ROS). Under the optimal experimental conditions, the ECL immunosensor exhibited good analytical performances for CYFRA21-1 detection with a wide linear range (100 fg mL-1 -100 ng mL-1 ) and a low limit of detection (85.20 fg mL-1 ), providing a promising method for early diagnosis of NSCLC.

A sensitive signal-on electrochemiluminescence sensor based on a nanocomposite of polypyrrole-Gd2O3 for the determination of L-cysteine in biological fluids.

A sensitive solid-state electrochemiluminescence (ECL) electrode for L-cysteine was developed based on depositing layers of a hybrid nanocomposite of polypyrrole-dodecyl benzene sulfate-sodium perchlorate-sodium carbonate-gadolinium (PPy-Gd2O3) on a platinum substrate. The presence of the Gd2O3 nanoparticle layer improved the ECL signal, and under optimum conditions, a linear relationship was observed between the signal and the logarithm of L-cysteine concentration from 1.0 × 10-13 to 1.0 × 10-6M (R2 = 0.9937). At the emission wavelengtharound 425 nm, at which the analytical signal was measured, the electrode showed an RSD of less than 4% and a low detection limit of 4.2 × 10-14M. The results proved to be reproducible and stable, and the electrode was applicable in the determination of L-cysteine in biological fluids with recoveries from 94.0-107%. Graphical abstract The results of this research indicated that the weak ECL of luminol is greatly improved by traces of L-cysteine on a solid-state platinum electrode coated with polypyrrole and gadolinium oxide nanoparticles (NPs) and have hence been effectively used in the analysis of L-cysteine in plasma and saliva.

A high sensitive single luminophore ratiometric electrochemiluminescence immunosensor in combined with anodic stripping voltammetry

Herein, we report a high sensitive ratiometric electrochemiluminescence (ECL) method for carcinoembryonic antigen (CEA) determination. Porous g-C3N4 nanosheets were immobilized on the surface of conductive polymer film doped with carbon nanotubes on glassy carbon electrode and used as ECL luminophore. Signal amplification was achieved by using CuS nanoparticles conjugated second antibody. After the immune recognition, the tag of CuS nanoparticles was dissolved and Cu(II) was electrochemically reduced to Cu on the surface of modified electrode at the potential of - 0.3 V (vs. Ag/AgCl), enhancing greatly the sensitivity. The cathodic ECL of g-C3N4 generated with K2S2O8 as the co-reactant was firstly measured and used as the reference signal in the ratiometric measurement. Afterwards, the anodic ECL of g-C3N4 was measured as the sensing signal with triethanolamine as the co-reactant. During the anodic ECL process, the pre-deposited Cu was stripped to Cu(II), which can quench the ECL signal with higher efficiency due to the short distance of g-C3N4 and Cu(II) within the Helmholtz layer on the electrode surface. In this ratiometric method, the amount of Cu(II) was determined to quantify the concentration of CEA in the range of 1 fg mL−1 to 0.1 ng mL−1, with the limit of detection of 0.3 fg mL−1, which is lower than that of 3 fg mL−1 in signal-on ECL immunesensor using g-C3N4 as the tag. The combination of biometallization and anodic stripping voltammetry with ratiometric ECL can enhance significantly the sensitivity and reliability in immunosensors.

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

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

Ultrasensitive electrochemiluminescence aptasensor for 8-hydroxy-2′-deoxyguanosine detection based on target-induced multi-DNA release and nicking enzyme amplification strategy

8-Hydroxy-2′-deoxyguanosine (8-OH-dG) is a principal stable marker of DNA oxidative damage. Sensitive and specific detection of 8-OH-dG is of great importance for early disease diagnosis. In this paper, we developed an electrochemiluminescence aptasensor for 8-OH-dG detection based on target induced multi-DNA release and nicking enzyme signaling amplification strategy. First, three kinds of short DNAs were aligned on the aptamers immobilized on the magnetic beads. In the presence of 8-OH-dG, the aptamer recognized and specifically bound with 8-OH-dG, leading to the release of three kinds of short DNAs and three-fold signal amplification. Then the released short DNAs hybridized with ferrocence (Fc) labeled hairpin DNA (Fc-HP) immobilized on the gold electrode to form a double strand DNA. Subsequently, nicking endonuclease (Nt.AlwI) recognized the asymmetric sequence in the dsDNA and cleaved the substrate strand (Fc-HP) into two parts, one fragments containing Fc would leave the surface of electrode. Based on the quenching effect of Fc on the electrochemiluminescence (ECL) of Ru(bpy)32+/TPA, a signal-on ECL aptasensor was developed. At the same time, three kinds of short DNAs were released again and reused to initiate the repeated cycles of hybridization-cleavage. Under double signal amplification, this aptasensor achieved a low detection of 25 fM and a wide linear range from 100 fM to 10 nM for 8-OH-dG. Besides, the amount of 8-OH-dG in urine samples derived from different people were determined with satisfactory results.

A label-free and signal-on electrochemiluminescence strategy for sensitive amyloid-beta assay

Development of a simple, cost-effective and sensitive biosensing strategy is highly desirable to advance the applications in Alzheimer's disease diagnosis. In this paper, we present a simple, label-free and signal-on electrochemiluminescence (ECL) aptasensor for the detection of amyloid-beta (Aβ) peptide using luminol as ECL emitter and in-situ generated reactive oxygen species (ROS) as coreactant via catalytic reaction between Cu2+-Aβ and the dissolved O2 in the presence of ascorbic acid (AA). Aβ16, the binding site of Cu2+ in the monomeric full-length Aβ, was used as a model in present study. As a result, this signal-on ECL aptasensor has exhibited favorable analytical performance for Aβ16 monomer with a linear range of 1.0 × 10-13 mol/L-1.0 × 10-8 mol/L and a limit of detection of 3.5 × 10-14 mol/L (S/N=3). Furthermore, the proposed biosensor was also able to detect the full length Aβ40 not only in the phosphate buffer saline (PBS) solution but also in human serum. The presented biosensor represents a promising, simple, turn-on and label-free diagnostic tool for blood analysis.

Signal-on electrochemiluminescence aptasensor for bisphenol A based on hybridization chain reaction and electrically heated electrode

A simple and sensitive electrochemiluminescence (ECL) aptasensor has been developed for bisphenol A (BPA) detection. The capture DNA (CDNA) was modified on the heated indium-tin-oxide (ITO) working electrode surface firstly and then hybridized with BPA aptamer to form double strand DNA (dsDNA). The presence of target can cause the releasing of aptamer from the electrode surface since the aptamer prefers to switch its configuration to combine with BPA. Subsequently, the free CDNA will induce hybridization chain reaction (HCR) to produce long dsDNA on the electrode surface. Ru(phen)32+ can integrate into the grooves of dsDNA to act as an ECL reagent, thus enhanced ECL signal can be detected. The temperature control during the processes of target recognition and HCR were realized through the heated electrode instead of the bulk solution heating. Furthermore, the performance of the ECL aptasensor can be further enhanced at elevated electrode temperature. Under the optimized conditions, the ECL intensity of the system has a linear relationship with the logarithm of BPA concentration in the range of 2.0 pM-50 nM. The limit of detection (LOD) at 55 °C (electrode surface temperature) was calculated to be 1.5 pM, which was approximately 6.5-fold lower than that at 25 °C. The proposed biosensor has been applied to detect the BPA in drink samples with satisfactory results.

Graphene quantum dots-based electrochemiluminescence detection of DNA using multiple cycling amplification strategy

In this study, a novel strategy for amplified electrochemiluminescence (ECL) detection of DNA was proposed based on excellent ECL activity of graphene quantum dots (GQDs) coupled with multiple cycling amplification technique. A new type of graphene QDs with well ECL property and uniform size were firstly synthesized, then the graphene QDs were assembled on the electrode by poly (diallyldimethylammonium chloride) (PDDA)-graphene oxide (GO) nanocomposites, which could greatly improve ECL signal and stability of QDs. A novel signal-on ECL biosensor for DNA analysis was designed by using ECL quenching of gold nanoparticles (NPs) to graphene QDs combined with endonuclease–aided cyclic amplification strategy. As a result, the proposed strategy can be conveniently expanded to other biosensing application, especially in clinical diagnoses.

A signal-on electrochemiluminescence sensor for clenbuterol detection based on zinc-based metal-organic framework-reduced graphene oxide-CdTe quantum dot hybrids.

Clenbuterol (CLB) is harmful to human health when used long term, and it has been listed by the World Anti-Doping Agency (WADA). In this work, a novel zinc-based metal-organic frameworks-reduced graphene oxide-CdTe quantum dots (ZnMOF-RGO-CdTe QDs) hybrid was used to construct an electrochemiluminescence (ECL) sensor for detecting CLB. CdTe QDs, loaded by RGO, exhibited an enhanced ECL signal. In addition, the ZnMOFs catalyzed OH• generation by coreactant H2O2, which further strengthened the ECL signal of the CdTe QDs. The integration of ZnMOFs and RGO-CdTe QDs endowed the sensor with high sensitivity for CLB detection. The intensity of the ECL signal increased as the concentration of CLB increased. The linear range of CLB detection was 3.0 × 10-13M to 6.0 × 10-10M, and the detection limit was estimated to be 1.0 × 10-13M. Furthermore, the sensor displayed a good repeatability and stability. The ZnMOF-RGO-CdTe QD hybrids described in this study provide a foundation for the development of new methods of detecting CLB. Graphical abstract ᅟ.

Signal-On Electrochemiluminescence of Self-Ordered Molybdenum Oxynitride Nanotube Arrays for Label-Free Cytosensing

In this paper, a signal-on electrochemiluminescence (ECL) cytosensing platform was developed based on nitrogen doped molybdenum oxynitride nanotube arrays (MoO xN y NTs) for the first time. The MoO xN y NTs exhibited excellent cathodic ECL behavior with 2-(dibutylamino)-ethanol (DBAE) as a coreactant. Owing to the surface plasmon resonance (SPR) of Au triggered by the ECL emission, the generation of "hot electrons" on AuNPs hampered DBAE to give off electrons and leads to the ECL quenching. This process could be hindered via adding "barriers" on the surface of AuNPs, such as antibody molecules and cells, to achieve the signal recovery. Based on the quenching-recovering mechanism, a facile label-free ECL cytosensor was constructed. The linear response of HepG2 cells was in the range of 50-13800 cells mL-1 with a low detection limit of 47 cells mL-1 (S/N = 3). Moreover, the proposed ECL cytosensor exhibits a satisfying performance in the practical application. Due to the anodic formation from a Mo metal substrate, the valuable feature is that the MoO xN y NTs-based ECL cytosensor can be used directly, thereby providing a stable and simplified ECL cytosensing platform for future clinical applications.

Signal-on electrochemiluminescence biosensor for microRNA-319a detection based on two-stage isothermal strand-displacement polymerase reaction

MicroRNAs play crucial role in regulating gene expression in organism, thus it is very necessary to exploit an efficient method for the sensitive and specific detection of microRNA. Herein, a signal-on electrochemiluminescence biosensor was fabricated for microRNA-319a detection based on two-stage isothermal strand-displacement polymerase reaction (ISDPR). In the presence of target microRNA, amounts of trigger DNA could be generated by the first ISDPR. Then, the trigger DNA and the primer hybridized simultaneously with the hairpin probe to open the stem of the probe, and then the ECL signal will be emitted. In the presence of phi29 DNA polymerase and dNTPs, the trigger DNA could be displaced to initiate a new cycle which was the second ISDPR. Due to the two-stage amplification, this method presented excellent detection sensitivity with a low detection limit of 0.14 fM. Moreover, the applicability of the developed method was demonstrated by detecting the change of microRNA-319a content in the leaves of rice seedlings after the rice seeds were incubated with chemical mutagen of ethyl methanesulfonate.

Detection of cyanide by etching-induced electrochemiluminescence recovery

Electrochemiluminescence (ECL) emission of gold nanoparticles (Au NPs) loaded graphitic carbon nitride nanosheets (Au-CNN nanohybrids) can be modulated by the Au content. On the basis, a signal-on ECL sensor for detecting cyanide, a widespread toxic chemical, has been developed in this work. The sensor utilizes cyanide-mediated etching of Au NPs to recover the ECL emission of Au-CNN nanohybrids initially inhibited by Fӧrster resonance energy transfer (FRET) from CNNs to Au NPs. The ECL sensor has a sensitive response to cyanide in the range of 50 nM to 1 mM with a detection limit of 50 nM, and shows high specificity due to the high affinity of Au-cyanide complex. The proposed FRET modulated ECL sensor may prove valuable in future environmental monitoring.

Sensitive electrochemiluminescent immunosensor for diabetic nephropathy analysis based on tris(bipyridine) ruthenium(II) derivative with binary intramolecular self-catalyzed property

Electrochemiluminescence (ECL) co-reaction and ECL resonance energy transfer (ECL-RET) are two main methods for enhancing the ECL efficiency. In this work, a novel tris(bipyridine) ruthenium(II) derivative (Ru(bpy)2(mcbpy)2+-PEI-ABEI) with high ECL efficiency due to the binary intramolecular ECL self-catalyzed property including intramolecular co-reaction and intramolecular ECL-RET, was prepared for the construction of immunosensor. Firstly, through intramolecular co-reaction, polyethyleneimine (PEI) with large amount of amine co-reactive groups (primary, secondary and tertiary amine) not only increased the ECL intensity of Ru(bpy)2(mcbpy)2+, but also improved the ECL signal of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). Meanwhile, ABEI, as an effective energy transfer donor, could further increase the ECL intensity of Ru(bpy)2(mcbpy)2+ (as energy transfer receptor) by intramolecular ECL-RET. It is worth noting that the strategy combined intramolecular co-reaction and intramolecular ECL-RET in the same ECL process was more effective for ECL efficiency enhancement compared with the traditional intermolecular interaction or individual intramolecular interaction, which would improve the sensitivity of immunosensor obviously. Thus, the proposed signal-on ECL immunosensor using convex hexoctahedral Pd@Au core-shell nanocrystals (Pd-Au HCDs) as immobilized platform exhibited a detected range for collagen type IV (Col IV), a typical biomarker of diabetic nephropathy (DN), from 0.5pgmL−1 to 7.2ngmL−1 with an estimated detection limit of 0.17pgmL−1. The developed strategy combined intramolecular co-reaction with intramolecular ECL-RET offered an effective mean for ECL methodology in ECL efficency enhancement and also provided possible road for early diagnosis and treatment monitoring of DN.

Methylation-induced inactivation of restriction enzyme for amplified and signal-on electrochemiluminescence detection of methyltransferase activity

Sensitive detection of DNA methyltransferase (MTase) activity plays important roles for the diagnosis of many types of genetic disorder diseases and human malignancies. In this work, we describe the development of a label-free, sensitive and signal-on electrochemiluminescence (ECL) method for detecting MTase activity based on a restriction enzyme inactivation strategy. The sequence-specific double stranded DNA (dsDNA) probes on the sensing electrode can be cleaved by the restriction enzyme to initiate hybridization chain reaction (HCR) formation of the supersandwich DNAzyme structures, which catalyze the reduction and depletion of the dissolved oxygen to significantly quench the ECL of the oxygen/persulfate (O2/S2O82−) system. The methylation of the dsDNA probes by DNA adenine methyltransferase (Dam MTase) can inactivate the restriction enzyme activity and inhibit subsequent HCR formation of the DNAzymes, leading to recovery of the ECL signal for signal-on detection of Dam MTase in a dynamic range from 0.01UmL−1 to 50UmL−1 with the detection limit of 6.4×10−3UmL−1. The inhibition of Dam MTase activity by different drugs is also evaluated, offering this method new opportunity for highly sensitive detection of Dam MTase activity and for screening potential drugs for cancer therapy as well.

A novel PAMAM-Au nanostructure-amplified CdSe quantum dots electrochemiluminescence for ultrasensitive immunoassay

A novel PAMAM dendrimers-Au nanostructure was prepared and used to develop an amplified CdSe quantum dots (QDs) probe for ultrasensitive electrochemiluminescence (ECL) immunoassay. The unique dendrimer-encapsulated Au nanoparticles have numerous functional groups for loading enough QDs, and the ECL of QDs was enhanced by the localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs). After the PAMAM dendrimer was used to form an effective immobilization matrix for biomolecules, the capture antibody (Ab1) was covalently conjugated to the dendrimers. In the presence of the target human IgG (Ag), the secondary antibody (Ab2) modified PAMAM-Au–CdSe QDs signal probe was attached to the electrode. On the basis of the amplified ECL signal of the CdSe QDs, an ultrasensitive signal-on ECL immunosensor was developed. The PAMAM-Au–CdSe QDs nanostructure opens a new promising material direction for ECL biosensing; this method shows considerable promise for diverse clinical applications.