量子点双标记的Fe3O4@Au磁性纳米DNA电致发光型传感器

合成了Fe3O4@Au磁性纳米粒子,并根据单链寡聚核苷酸(ss-DNA)杂交原理,利用量子点电化学发光,构建了DNA电化学传感器.在磁控玻碳电极(MCGCE)表面,将5′-SH-ssDNA捕获探针自组装在Fe3O4@Au磁性纳米粒子上,然后与目标DNA互补的一端杂交形成dsDNA,再与双标记了量子点的5′-NH2-ssDNA-NH2-3′信号探针杂交形成三明治杂交的DNA.应用循环伏安法对DNA的固定与杂交进行了表征.目标DNA浓度在1.0×10-13～1.0×10-11 mol/L范围与其响应的ECL信号呈线性关系,检出限为1.8×10-14mol/L.由于采用量子点双标记法,检测的灵敏度显著提高.     

Design of Sensitive Biocompatible Quantum‐Dots Embedded in Mesoporous Silica Microspheres for the Quantitative Immunoassay of Human Immunodeficiency Virus‐1 Antibodies

A novel sandwich‐type electrochemiluminescence (ECL) immunosensor was developed to enable the sensitive detection of HIV‐1 antibodies. This system incorporated mesoporous silica (mSiO₂) complexed with quantum dots (QDs) and nano‐gold particles, which were assembled to enhance signal detection. Magnetic beads were used by immobilizing the secondary anti‐IgG antibody. This was first employed to capture HIV‐1 antibody (Ab) to form a Fe₃O₄/anti‐IgG/Ab complex. A high loading and signal‐enhanced nanocomposite (hereafter referred to as Au‐mSiO₂‐CdTe) was used as a HIV‐1 antigen label. The Au‐mSiO₂‐CdTe nanocomposite was conjugated with the Fe₃O₄/anti‐IgG/Ab complex to form an immunocomplex (hereafter referred to as Fe₃O₄/anti‐IgG/Ab/HIV‐1/CdTe‐mSiO₂‐Au). This complex could be further separated by an external magnetic field to produce ECL signals. Due to the large specific surface area and pore volume of mSiO₂, the loading of the CdTe QDs was markedly increased. Thus, the loaded QDs released a powerful chemiluminescent signal with a concordantly increased sensitivity of the immunosensor. The immunosensor was highly sensitive, and displayed a linear range of responses for HIV‐1 antibody across a dilution range of 1 : 1500 through 1 : 50 with the detection limit of 1 : 4500. The immunoassay can be a promising candidate in early diagnosis of HIV infection.     

Electrochemiluminescence immunoassay at a nanoporous gold leaf electrode and using CdTe quantun dots as labels

An electrochemiluminescence-based immunoassay using quantum dots (QDs) as labels for the carcinoembryonic antigen (CEA) was developed using an electrode modified with leafs of nanoporous gold. CEA was initially immobilized on the electrode via a sandwich immunoreaction, and then CdTe quantum dots capped with thioglycolic acid were used to label the second antibody. The intensity of the ECL of the QDs reflects the quantity of CEA immobilized on the electrode. Thus, in the presence of dithiopersulfate as the coreactant, the ECL serves as the signal for the determination of CEA. The intensity of the electroluminescence (ECL) of the electrode was about 5.5-fold higher than that obtained with a bare gold electrode. The relation between ECL intensity and CEA concentration is linear in the range from 0.05 to 200?ng.mL^-1, and the detection limit is 0.01?ng.mL^-1. The method has the advantages of high sensitivity, good reproducibility and long-term stability, and paves a new avenue for applying quantum dots in ECL-based bioassays.

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties: synthesis and biological application

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties were fabricated and used as biological labels. The Fe(3)O(4)@MnCO(3) microspheres were synthesized by direct co-precipitation without any linker shell. The Fe(3)O(4)@MnCO(3) microspheres have uniform size distribution and rough surface, which provides a promising template for the assembly of polyelectrolytes (PEs) and CdTe quantum dots (QDs). A luminescent CdTe shell was observed in Fe(3)O(4)@MnCO(3)@PE-CdTe spheres by confocal fluorescence imaging. With excellent solubility in water and rough surfaces, the multifunctional microsphere offers a friendly microenvironment for immobilization of α-fetoprotein (AFP) antibodies (Ab(2)) to fabricate Fe(3)O(4)@MnCO(3)@PE-CdTe-Ab(2) architecture. By using the Fe(3)O(4) @MnCO(3)@PEs-CdTe-Ab(2) bioconjugate as a label, a promising and versatile platform for fluorescence imaging and electrochemical immunosensing of cancer biomarker AFP was developed. The prepared electrochemical immunosensor shows high sensitivity and selectivity with a detection limit of 0.3 pg mL(-1).     

磁性量子点电致化学发光法测定李氏禾提取液中的过氧化氢

利用巯基乙酸水热法合成出表面修饰—COOH的CdTe量子点,并将CdTe量子点(QDs)连接在Fe3O4纳米粒子表面,制备出CdTe/Fe3O4磁性量子点。通过磁力将磁性量子点修饰于石墨电极表面。在pH7.5的PBS缓冲溶液中,H2O2可使CdTe量子点产生电致化学发光,H2O2浓度在4～100μmol/L范围内与CdTe量子点的电致化学发光强度呈良好的线性关系,检出限为0.24μmol/L。据此建立了测定样品中过氧化氢含量的电致化学发光分析法,并成功地应用于李氏禾草汁原液中过氧化氢含量的测定。该研究借助纳米Fe3O4的磁力特征,使敏感膜易于形成和更新分离,简化了实验操作,同时起到增强发光强度的作用。     

Multiple signal amplified electrochemiluminescent immunoassay for brombuterol detection using gold nanoparticles and polyamidoamine dendrimers-silver nanoribbon

Electrochemiluminescent (ECL) immunosensor with multiple signal amplification was designed based on gold nanoparticles (AuNPs), polyamidoamine dendrimers (PAMAM) and silver-cysteine hybrid nanoribbon (SNR). Low toxic l-cysteine capped CdSe QDs was chosen as the ECL signal probe. To verify the proposed ultrasensitive ECL immunosensor for β-adrenergic agonists (β-AA), we detected Brombuterol (Brom) as a proof-of-principle analyte. Therein, AuNPs as the substrate can simplify the experiment process, accelerate the electron transfer rate, and carry more coating antigen (Ag-OVA) to enlarge ECL signal. On one hand, SNR on the surface of electrode can avoid the aggregation of AuNPs, and SNR-PAMAM-AuNPs also can be acted as a good accelerator for electron transfer. On the other hand, PAMAM (16 -NH₂) functionalized SNR (SNR-PAMAM) with numerous amino groups could be employed to bond abundant actived QDs to further amplify ECL signal. The new immunosensor can offer a simple, reliable, rapid, and selective detection for Brom, which have a dynamic range of 0.005–700 ng mL⁻¹ with a low detection limit at 1.5 pg mL⁻¹. The proposed biosensor will extend the application of nanomaterials in ECL immunoassays and open a new road for the detection of Brom and other β-AA in the future.     

Separation/Concentration‐signal‐amplification in‐One Method Based on Electrochemical Conversion of Magnetic Nanoparticles for Electrochemical Biosensing

We propose a separation/concentration‐signal‐amplification in‐one method based on electrochemical conversion (ECC) of magnetic nanoparticles (MNPs) to develop a facile and sensitive electrochemical biosensor for chloramphenicol (CAP) detection. Briefly, aptamer‐modified magnetic nanoparticles (MNPs‐Apt) was designed to capture CAP in sample, then the MNPs‐Apt composite was conjugated to Au electrode through the DNA hybridization between the unoccupied aptamer and a strand of complementary DNA. The ECC method was applied to transfer MNPs labels to electrochemically active Prussian blue (PB). The anodic and cathodic currents of PB were taken for signal readout. Comparing with conventional methods that require electrochemically active labels and related sophisticated labelling procedures, this method explored and integrated the magnetic and electrochemical properties of MNPs into one system, in turn realized magnetic capturing of CAP and signal generation without any additional conventional labels. Taking advantages of the high abundance of iron content in MNPs and the refreshing effect deriving from ECC process, the method significantly promoted the signal amplification. Therefore, the proposed biosensors exhibited linear detection range from 1 to 1000 ng mL⁻¹ and a limit of detection down to 1 ng mL⁻¹, which was better than or comparable with those of most analogues, as well as satisfactory specificity, storage stability and feasibility for real samples. The developed method may lead to new concept for rapid and facile biosensing in food safety, clinic diagnose/therapy and environmental monitoring fields.     

Magnetic electrochemiluminescent Fe3O4/CdSe-CdS nanoparticle/polyelectrolyte nanocomposite for highly efficient immunosensing of a cancer biomarker

Magnetic electrochemiluminescent Fe₃O₄/CdSe–CdS nanoparticle/polyelectrolyte nanostructures have been synthesized and used to fabricate an electrochemiluminescence (ECL) immunosensor for the detection of carcinoembryonic antigen (CEA). CEA is a protein used as a biomarker for several cancers; particularly, to monitor response to treatment in colon and rectal cancer patients. The nanocomposites can be easily separated and firmly attached to an electrode owing to their excellent magnetic properties. This represents a promising advantage for bioassay applications. More importantly, the nanostructures exhibit intense and stable ECL emissions in neutral solution, which makes them ideal for ECL immunosensing. The 3‐aminopropyltriethoxysilane (APS) polyelectrolyte shell on the nanostructure surface not only enhances the intensity and stability of the ECL signal, but also acts as a crosslinker for immunosensor fabrication. A CEA antibody immobilized onto a nanocomposite/APS/electrode with gold nanoparticles comprises the ECL immunosensor. The principle of ECL detection for CEA is based on a change in steric hindrance after immunoreaction, which leads to a decrease in ECL intensity. A wide detection range (0.064 pg ml^?1–10 ng ml^?1) and low detection limit (0.032 pg ml^?1) are achieved. The immunosensor is highly sensitive and selective, and exhibits excellent stability and good reproducibility. It thus has great potential for clinical protein detection. In particular, this approach uses a novel class of bifunctional nanocomposites that display both intense ECL and excellent magnetism, which renders them suitable for a large range of bioassay applications.     

Ultrasensitive electrochemiluminescence immunosensor using PtAg@carbon nanocrystals composites as labels and carbon nanotubes-chitosan/gold nanoparticles as enhancer

An ultrasensitive electrochemiluminescence (ECL) immunosensor was developed using PtAg@carbon nanocrystals (CNCs) as excellent labels based on carbon nanotubes-chitosan/AuNPs (CNT-CHIT/AuNPs) composite modified screen-printed carbon electrodes (SPCEs) for prostate protein antigen (PSA) detection. The CNCs were obtained simply by electro-oxidation of graphite with abundant carboxyl groups at their surfaces. The PtAg bimetallic nanocomposites with hierarchically hollow structures were fabricated through simple replacement reaction using dealloyed nanoporous silver (NPS) as both a template and reducing agent. Structure characterization was obtained by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) images. The PtAg@CNCs composites exhibit a 6 times higher ECL intensity than the pure CNCs labeled anti-PSA. The as-prepared CNT-CHIT/AuNPs composite can attach more antibody than pure CNTs. Due to the dual-amplification techniques, the concentrations of PSA were obtained in the range from 1 pg mL(-1) to 50 ng mL(-1) with a detection limit of 0.6 pg mL(-1). Finally, the as-proposed ECL immunosensor has the advantages of high sensitivity, specificity and stability and could become a promising technique for tumor marker detection.     

Nanoscale-enhanced Ru(bpy)3(2+) electrochemiluminescence labels and related aptamer-based biosensing system

A unique multilabeling at a single-site protocol of the Ru(bpy)(3)(2+) electrochemiluminescence (ECL) system is proposed. Nanoparticles (NPs) were used as assembly substrates to enrich ECL co-reactants of Ru(bpy)(3)(2+) to construct nanoscale-enhanced ECL labels. Two different kinds of NP substrates [including semiconductor NPs (CdTe) and noble metal NPs (gold)] capped with 2-(dimethylamino)ethanethiol (DMAET) [a tertiary amine derivative which is believed to be one of the most efficient of co-reactants of the Ru(bpy)(3)(2+) system] were synthesized through a simple one-pot synthesis method in aqueous media. Although both CdTe and gold NPs realized the enrichment of ECL co-reactants, they presented entirely different ECL performances as nanoscale ECL co-reactants of Ru(bpy)(3)(2+). The different effects of these two NPs on the ECL of Ru(bpy)(3)(2+) were studied. DMAET-capped CdTe NPs showed enormous signal amplification of Ru(bpy)(3)(2+) ECL, whereas DMAET-capped gold NPs showed a slight quenching effect of the ECL signal. DMAET-capped CdTe NPs can be considered to be excellent nanoscale ECL labels of the Ru(bpy)(3)(2+) system, as even a NP solution sample of 10(-18) M was still detectable after an electrostatic self-assembly concentration process. DMAET-capped CdTe NPs were further applied in the construction of aptamer-based biosensing system for proteins and encouraging results were obtained.     

Highly sensitive luminol electrochemiluminescence immunosensor based on ZnO nanoparticles and glucose oxidase decorated graphene for cancer biomarker detection

In this work, we reported a sandwiched luminol electrochemiluminescence (ECL) immunosensor using ZnO nanoparticles (ZnONPs) and glucose oxidase (GOD) decorated graphene as labels and in situ generated hydrogen peroxide as coreactant. In order to construct the base of the immunosensor, a hybrid architecture of Au nanoparticles and graphene by reduction of HAuCl₄ and graphene oxide (GO) with ascorbic acid was prepared. The resulted hybrid architecture modified electrode provided an excellent platform for immobilization of antibody with good bioactivity and stability. Then, ZnONPs and GOD functionalized graphene labeled secondary antibody was designed for fabricating a novel sandwiched ECL immunosensor. Enhanced sensitivity was obtained by in situ generating hydrogen peroxide with glucose oxidase and the catalysis of ZnONPs to the ECL reaction of luminol–H₂O₂ system. The as-prepared ECL immunosensor exhibited excellent analytical property for the detection of carcinoembryonic antigen (CEA) in the range from 10 pg mL⁻¹ to 80 ng mL⁻¹ and with a detection limit of 3.3 pg mL⁻¹ (S N⁻¹ = 3). The amplification strategy performed good promise for clinical application of screening of cancer biomarkers.     

Highly sensitive hybridization assay using the electrochemiluminescence of an ITO electrode, CdTe quantum dots functionalized with hierarchical nanoporous PtFe nanoparticles, and magnetic graphene nanosheets

We report on a disposable microdevice suitable for sandwich-type electrochemiluminescence (ECL) detection of DNA. The method is making use of CdTe quantum dots functionalized with hierarchical nanoporous PtFe (CdTe@PtFe) nanoparticles and with magnetic graphene nanosheets. The latter were selected as carriers for the capture DNA due to their excellent biomagnetic separation capability and electrical properties. The CdTe@PtFe nanoparticles were used to label the signal DNA which resulted in distinctly enhanced ECL owing to the large specific surface area and good electrical conductivity of the PtFe alloy. A DNA sensor was constructed on a disk-shaped indium tin oxide electrode that was fabricated via etching. Under optimal conditions, the biosensor responds linearly to DNA in the 0.02 fM to 5000 fM concentration range, with a detection limit as low as 15 aM. The electrode is regenerable. The method displays excellent specificity, extremely good sensitivity, and is highly reproducible.

Ultrasensitive electrochemiluminescence immunoassay for tumor marker detection using functionalized Ru-silica@nanoporous gold composite as labels

In this work, we reported a simple and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor for carcinoembryonic antigen (CEA) on a gold nanoparticles (AuNPs) modified glassy carbon electrode (GCE). The Ru-silica (Ru(bpy)(3)(2+)-doped silica) capped nanoporous gold (NPG) (Ru-silica@NPG) composite was used as an excellent label with amplification techniques. The NPG was prepared with a simple dealloying strategy, by which silver was dissolved from silver/gold alloys in nitric acid. The primary antibody was immobilized on the AuNPs modified electrode through l-cysteine and glutaraldehyde, and then the antigen and the functionalized Ru-silica@NPG composite labeled secondary antibody were conjugated successively to form a sandwich-type immunocomplex through the specific interaction. The concentrations of CEA were obtained in the range from 1 pg mL(-1) to 10 ng mL(-1) with a detection limit of 0.8 pg mL(-1). The as-proposed ECL immunosensor has the advantages of high sensitivity, specificity and stability and could become a promising technique for tumor marker detection.     

Electrochemiluminescence of Dendritic Magnetic Quantum Dots Nanostructure and Its Quenching by Gold Nanoparticles for Cancer Cells Assay

A novel dendritic CdS‐ZnS‐Quantum Dots (QDs) nanocomposite with intense electrochemiluminescence (ECL) and excellent magnetism was prepared, which was applied to the cancer cells assay based on ECL quenching of QDs by gold nanoparticles (NPs). DNA conjugation, gold NPs linking and sensing target cells can be directly performed on the magnetic nanocomposites, which is more rapid, convenient, and has better reproducibility than the conventional methods. So far, this is the first report on magnetic electrochemiluminescent QDs nanocomposites for cell detection based on ECL quenching, which opens a new approach for developing multifunctional QDs nanocomposite for ECL assays of cancer cells.     

Electrochemiluminescence immunosensor based on nanocomposite film of CdS quantum dots-carbon nanotubes combined with gold nanoparticles-chitosan

A novel and sensitive electrochemiluminescence (ECL) immunosensor based on CdS quantum dots (QDs)-carbon nanotubes (CNTs) and gold nanoparticles-chitosan (GNPs-CHIT) was presented. CdS QDs ECL was much enhanced by combing poly(diallyldimethylammonium chloride) functionalized CNTs. GNPs-CHIT nanohybrids was used to construct an effective antibody immobilization matrix with excellent stability and bioactivity. The principle of ECL detection for target human IgG is based on the increment of steric hindrance after immunoreaction, which resulted in the decrease in ECL intensity. The linear response range was between 0.006 and 150 ng mL^?1, and the detection limit was 0.001 ng mL^?1. This approach offers obvious advantages of being simpler, faster, and more stable compared with other immunosensors, which possesses great potential for protein detection in clinical laboratory.     

基于花状铂纳米颗粒构建的电致化学发光免疫传感器用于检测载脂蛋白A1

采用一锅合成法制备了新型的具有大比表面积的花状铂纳米颗粒（PtNFs）,并构建了一个高灵敏电致化学发光（ECL）免疫传感器用于检测载脂蛋白A1（Apo-A1）. 该PtNFs用于吸附二抗（anti-Apo-A1）,并用葡糖糖氧化酶（GOD）封闭其表面的非特异性位点,最终制备了PtNFs@anti-Apo-A1@GOD信号探针. 当Apo-A1存在时,通过夹心免疫反应将制备的信号探针捕获于电极表面,并将所制得的电极置于含有葡萄糖的过硫酸根底液中检测. GOD催化葡萄糖产生H₂O₂,H₂O₂在PtNFs的催化下分解并在电极表面原位产生O₂,所产生的O₂能够催化过硫酸根-氧气体系的电致化学发光反应,放大发光信号,提高检测灵敏度. 该传感器在0.1ng•mL^-1 ~ 100 ng•mL^-1范围内对Apo-A1有良好的线性响应,检测下限达到0.03ng•mL^-1,有望应用于临床分析诊断.     

Electochemiluminescence of CdTe/CdS Quantum Dots with Triproprylamine as Coreactant in Aqueous Solution at a Lower Potential and Its Application for Highly Sensitive and Selective Detection of Cu2+

Anodic electrochemiluminescence (ECL) of 3‐mercaptopropionic acid (MPA)‐ capped CdTe/CdS core‐shell quantum dots (QDs) with tripropylamine (TPrA) as the co‐reactant were studied in aqueous (Tris buffer) solution for the first time. The results suggest that the oxidation of TPrA at a glassy carbon electrode (GCE) surface participated in the ECL of QDs, and the onset potential and the intensity of ECL of CdTe/CdS QDs were affected seriously by TPrA, as the co‐reactant, in Tris buffer solution. The onset potential of ECL in this new system was about +0.5 V (vs. Ag/AgCl) and the ECL intensity greatly enhanced when TPrA was present. Various influencing factors, such as the electrolyte, pH, QDs concentration, potential range and scan rates on the ECL were studied. Based on the selective quenching by Cu²⁺ to the light emission from CdTe/CdS QDs/TPrA system, a highly sensitive and selective method for the determination of Cu²⁺ was developed. At the optimal conditions, the relative ECL intensity, I₀/I, was proportional to the concentration of Cu²⁺ from 14 nM to 0.21 μM with the detection limit of 6.1 nM based on the signal‐to‐noise ratio of 3. The possible ECL mechanism of QDs and the quenching mechanism of ECL were proposed.     

CdSe quantum dots as labels for sensitive immunoassay of cancer biomarker proteins by electrogenerated chemiluminescence

A sensitive and specific immunoassay method for detecting α-fetoprotein (AFP) based on electrogenerated chemiluminescence (ECL) was described. ECL could perform detection for a series of different concentrations of AFP. CdSe quantum dots (QDs) were used as labels and were linked to AFP antibody (anti-AFP, the secondary antibody, Ab2*). Immunoassay was carried out on a modified electrode using a sandwich assay approach, where anti-AFP (Ab1) was covalently bound to the surface of an Au electrode to be allowed to capture AFP specifically. Afterwards, Ab2* was allowed to bind selectively to the captured AFP. The non-specific adsorption was negligible. In the presence of H(2)O(2), the ECL intensity increased with the increase of AFP, which indicated that an immunosensor for AFP was constructed. The detection of AFP based on measuring the ECL intensity of CdSe without the enzyme and mediator can promote the stability of the immunosensor. The linear range of the AFP assay was from 0.002 to 32 ng mL(-1). Furthermore, the immunosensor showed high sensitivity, good precision, stability, and reproducibility and could be used for the detection of real samples with consistent results in comparison with those obtained by the enzyme-linked immunosorbent assay (ELISA) method. The strategy was successfully demonstrated as a simple, cost-effective, specific, and potential method to detect AFP in practical samples.     

Highly enhanced electrochemiluminescent strategy for tumor biomarkers detection with in situ generation of l-homocysteine for signal amplification

In this work, an ultrasensitive peroxydisulfate electrochemiluminescence (ECL) immunosensor using in situ generation of l-homocysteine (l-Hcys) for signal amplification was successfully constructed for detection of carcinoembryonic antigen (CEA). In the reaction of biological methylation, S-adenosyl-l-homocysteine hydrolase (SAHH) catalyzed the reversible hydrolysis of S-adenosyl-l-homocysteine (SAH) to produce l-Hcys, which was inducted into ECL system to construct the immunosensor for signal amplification in this work. Simultaneously, Gold and palladium nanoparticles functionalized multi-walled carbon nanotubes (Au-PdNPs@MWCNTs) were prepared, which were introduced to immobilize the secondary antibody (Ab₂) and SAHH with high loading amount and good biological activity due to their improved surface area and excellent biocompatibility. Then the proposed ECL immunosensor was developed by a sandwich-type format using Au-PdNPs@MWCNTs-SAHH-Ab₂ as tracer and graphene together with AuNPs as substrate. Besides the enhancement of Au-PdNPs, the enzymatic catalysis reaction also amplified the ECL signal dramatically, which was achieved by efficient catalysis of the SAHH towards the hydrolysis of SAH to generate improved amount of l-Hcys in situ. Furthermore, due to the special interaction between Au-PdNPs and -SH or -NH₂ in l-Hcys, l-Hcys would gradually accumulate on the surface of the immunosensor, which greatly enhanced the concentration of l-Hcys on the immunosensor surface and further improved the ECL intensity. With the amplification factors above, a wide linear ranged from 0.1 pg mL⁻¹ to 80 ng mL⁻¹ was acquired with a relatively low detection limit of 33 fg mL⁻¹ for CEA.     

Ultrasensitive Electrochemiluminescence Biosensor for mRNA Based on Polymerase Assisted Signal Amplification

A novel biosensor for ultra‐trace mRNA sensing was constructed based on isothermal circular strand‐replacement polymerization (CSRP) to amplify the electrochmeiluminescence (ECL) signal by combining quantum dots (CdTe) as luminophore. After the hairpin‐like capture DNA was opened by hybridization with target mRNA, the additive primer (DNA1) was able to get access to its complementary sequence which is partially belong to the stem part and triggered a polymerization of DNA strand, leading to the release of target mRNA and another polymerization cycle. The remaining sequence of the stem part continued to hybridize with QDs labeled DNA, accomplishing ECL signal amplification. Target mRNA could be specifically assayed with a linear relationship between the signal intensity and the logarithm of concentrations of target DNA in the range of 1.0×10⁻¹⁴∼5.0×10⁻¹⁰ M, with a low detection limit of 1.4×10⁻¹⁵ M. The signal could discriminate perfect matched target mRNA from 1‐base mismatch sequence. This proposed ECL biosensor exhibited an efficient performance in serum sample, opening new opportunities for genetic target analysis in diagnostic and clinic biomedical fields.