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1.
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)(3)(2+)) (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)(3)(2+) 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 0.001-30 nM. The detection limit of the proposed aptasensor is 0.4 pM. Thus, the approach is expected to open new opportunities for protein diagnostics in clinical as well as bioanalysis in general.  相似文献   

2.
A novel electrochemical immunosensor for sensitive detection of α-synuclein (α-SYN), a very important neuronal protein, has been developed based on dual signal amplification strategy. Herein, G4-polyamidoamine dendrimer-encapsulated Au nanoparticles (PAMAM-Au nanocomposites) were covalently bound on the poly-o-aminobenzoic acid (poly-o-ABA), which was initially electropolymerized on the electrode surface to perform abundant carboxyl groups. The formed immunosensor platform, PAMAM-Au, was proved to provide numerous amino groups to allow highly dense immobilization of antigen, and facilitate the improvement of electrochemical responses as well. Subsequently, the enhanced gold nanoparticle labels ({HRP-Ab(2)-GNPs}) were fabricated by immobilizing horseradish peroxidase-secondary antibody (HRP-Ab(2)) on the surface of gold nanoparticles (GNPs). After an immunoassay process, the {HRP-Ab(2)-GNPs} labels were introduced onto the electrode surface, and produced an electrocatalytic response by reduction of hydrogen peroxide (H(2)O(2)) in the presence of enzymatically oxidized thionine. On the basis of the dual signal amplification of PAMAM-Au and {HRP-Ab(2)-GNPs} labels, the designed immunosensor displayed an excellent analytical performance with high sensitivity and stability. This developed strategy was successfully proved as a simple, cost-effective method, and could be easily extended to other protein analysis schemes.  相似文献   

3.
A composite of the metal–organic framework compound ZIF-8 doped with CdSe quantum dots (QDs) with sensitive and stable luminescence was synthesized, and a molecularly imprinted electrochemiluminescence (ECL) sensor was constructed based on this composite. The ZIF-8@CdSe molecularly imprinted ECL sensor combines the high sensitivity of ECL and the high selectivity of molecular imprinting to realize the sensitive and specific detection of estriol. CdSe QDs and gold nanoparticles were encapsulated within ZIF-8 to obtain the ZIF-8@CdSe QDs/GNP (ZIF@CdSe/GNP) composite. Subsequently, the GNPs were further loaded on the surface of this composite to obtain the GNP/ZIF@CdSe/GNP composite. l -Cysteine was used to immobilize the GNP/ZIF@CdSe/GNP composite on the surface of a gold electrode to obtain the GNP/ZIF@CdSe/GNP-modified gold electrode. A molecularly imprinted polymer (MIP) film was prepared on the surface of the modified electrode by electropolymerization with o-phenylenediamine as the functional monomer and estriol as the template molecule. After elution, estriol could be specifically recognized by the cavities. The readsorption of estriol by the MIP can prevent the coreactant from reaching the electrode surface through the cavities, thereby weakening ECL. A good linear relationship existed between the ∆ECL and lg C of estriol concentrations of 1 × 10−14 to 1 × 10−9 mol·L−1. The detection limit was as low as 8.9 × 10−16 mol·L−1. The sensor was applied in the determination of estriol in serum samples with a recovery of 97.0–102%.  相似文献   

4.
In this paper, a novel acetylcholinesterase (AChE) biosensor was constructed by modifying glassy carbon electrode with CdTe quantum dots (QDs) and excellent conductive gold nanoparticles (GNPs) though chitosan microspheres to immobilize AChE. Since GNPs have shown widespread use particularly for constructing electrochemical biosensors through their high electron-transfer ability, the combined AChE exhibited high affinity to its substrate and thus a sensitive, fast and cheap method for determination of monocrotophos. The combination of CdTe QDs and GNPs promoted electron transfer and catalyzed the electro-oxidation of thiocholine, thus amplifying the detection sensitivity. This novel biosensing platform based on CdTe QDs-GNPs composite responded even more sensitively than that on CdTe QDs or GNPs alone because of the presence of synergistic effects in CdTe-GNPs film. The inhibition of monocrotophos was proportional to its concentration in two ranges, from 1 to 1000ngmL(-1) and from 2 to 15mugmL(-1), with a detection limit of 0.3ngmL(-1). The proposed biosensor showed good precision and reproducibility, acceptable stability and accuracy in garlic samples analysis.  相似文献   

5.
Quantum dots (QDs) have been encapsulated within gelatin nanoparticles (GNPs), which gives GNPs fluorescent properties and improves the biocompatibility of QDs. Hydrophilic CdSe QDs were produced through thermodecomposition following the ligand‐exchange method, and were then encapsulated in GNPs. The results of high‐resolution transmission electron microscopy and transmission electron microscopy show that CdSe QDs and QDs‐encapsulated GNPs (QDs‐GNPs) have average diameters of 5 ± 1 and 150 ± 10 nm, respectively. Results of both high‐resolution transmission electron microscopy and confocal laser scanning microscopy indicate that CdSe QDs are successfully encapsulated within GNPs. The QDs‐GNPs have distinctive fluorescent properties with maximum emission at 654 nm, with a 24 nm red‐shift comapred with hydrophilic mercaptoundecanoic acid (MUA)‐modified QDs. In addition, an in vitro cytotoxicity test shows that QDs‐GNPs do not have any toxic effect on cells. It is expected that QDs‐GNPs might be an excellent candidate as a contrast agent in bio‐imaging. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

6.
A novel electrogenerated chemiluminescence (ECL) biosensor for highly sensitive and selective detection of mercury ion was developed on the basis of mercury-specific oligonucleotide (MSO) served as a molecular recognition element and the ruthenium(II) complex (Ru1) as an ECL emitting species. The biosensor was fabricated on a glassy carbon electrode coated with a thin layer of single wall carbon nanotubes, where the ECL probe, NH(2)-(CH(2))(6)-oligo(ethylene oxide)(6)-MSO?Dend-Ru1, was covalently attached. The Dend-Ru1 pendant was prepared by covalent coupling Ru1 with the 4th generation polyamidoamine dendrimer (Dend), in which each dendrimer contained 35 Ru1 units so that a large amplification of ECL signal was obtained. Upon binding of Hg(2+) to thymine (T) bases of the MSO, the T-Hg-T structure was formed, and the MSO changed from its linear shape to a "hairpin" configuration. Consequently, the Dend-Ru1 approached the electrode surface resulting in the increase of anodic ECL signal in the presence of the ECL coreactant tri-n-propylamine. The reported biosensor showed a high reproducibility and possessed long-term storage stability (92.3% initial ECL recovery over 30 day's storage). An extremely low detection limit of 2.4 pM and a large dynamic range of 7.0 pM to 50 nM Hg(2+) were obtained. An apparent binding constant of 1.6 × 10(9)M(-1) between Hg(2+) and the MSO was estimated using an ECL based extended Langmuir isotherm approach involving multilayer adsorption. Determination of Hg(2+) contents in real water samples was conducted and the data were consistent with the results from cold vapor atomic fluorescence spectroscopy.  相似文献   

7.
Listeria monocytogenes (L. monocytogenes) is one of the most problematic human pathogens, as it is mainly transmitted through the food chain and cause listeriosis. Thus, specific and sensitive detection of L. monocytogenes is required to ensure food safety. In this study, we proposed a method using hyperbranching rolling circle amplification (HRCA) combined with magnetic beads based electrochemiluminescence (ECL) to offer an isothermal, highly sensitive and specific assay for the detection of L. monocytogenes. At first, a linear padlock probe was designed to target a specific sequence in the hly gene which is specific to L. monocytogenes and then ligated by Taq DNA ligase. After ligation and digestion, further amplification by HRCA with a biotiny labeled primer and a tris (bipyridine) ruthenium (TBR) labeled primer was performed. The resulting HRCA products were then captured onto streptavidin-coated paramagnetic beads and were analyzed by magnetic beads based ECL platform to confirm the presence of targets. Through this approach, as low as 10 aM synthetic hly gene targets and about 0.0002 ng/μl of genomic DNA from L. monocytogenes can be detected, the ability to detect at such ultratrace levels could be attributed to the powerful amplification of HRCA and the high sensitivity of current magnetic bead based ECL detection platform.  相似文献   

8.
A signal amplification system for electrochemiluminescence (ECL) of quantum dots (QDs) was developed by using electrochemically reduced graphene oxide (ERGO) to construct a nanobiosensing platform. Due to the structural defects of GO, the ECL emission of QDs coated on GO modified electrode was significantly quenched. After the electrochemical reduction of GO, the restoration of structural conjugation was observed with spectroscopic, morphologic and impedance techniques. Thus in the presence of dissolved O? as coreactant, the QDs/ERGO modified electrode showed ECL intensity increase by 4.2 and 178.9 times as compared with intrinsic QDs and QDs/GO modified electrodes due to the adsorption of dissolved O? on ERGO and the facilitated electron transfer. After choline oxidase (ChO) or ChO-acetylcholinesterase was further covalently cross-linked on the QDs/ERGO modified electrode, two ECL biosensors for choline and acetylcholine were fabricated, which showed the linear response ranges and detection limits of 10-210 μM and 8.8 μM for choline, and 10-250 μM and 4.7 μM for acetylcholine, respectively. This green and facile approach to prepare graphene-QDs system could be of potential applications in electronic device and bioanalysis.  相似文献   

9.
A novel and sensitive fluorescence biosensor based on aptamer and rolling circle amplification for the determination of cocaine was developed in the present work. Here cocaine aptamers immobilized onto Au nanoparticles modified magnetic beads hybridized with short DNA strand. In the presence of cocaine, the short DNA strand was displaced from aptamer owing to cocaine specially binding with aptamer. Next, the short DNA strand was separated by magnetic beads and used to originate rolling circle amplification as primer. The end products of rolling circle amplification were detected by fluorescence signal generation upon molecular beacons hybridizing with the end products of rolling circle amplification. With rolling circle amplification and the separation by magnetic beads reducing the background signal, the new strategy was suitable for the detection of as low as 0.48 nM cocaine. Compared with reported cocaine sensors, our method exhibited excellent sensitivity. Our new strategy may provide a platform for numerous proteins and low molecular weight analytes to highly sensitively detect by DNA amplification.  相似文献   

10.
A novel label free electrochemiluminescence (ECL) immunosensor based on the ECL of peroxydisulfate solution for detection of α-1-fetoprotein (AFP) has been developed. For this proposed immunosensor, L-cysteine was firstly electrodeposited on the gold electrode surface, which promoted the electron transfer and largely enhanced the ECL of peroxydisulfate solution. Subsequently, gold nanoparticles (nano-Au) were assembled onto the L-cysteine film modified electrode to improve the absorption capacity of antibody and further amplify the ECL signal. Then, antibody was immobilized onto the electrode through nano-Au. At last bovine serum albumin (BSA) was employed to block the nonspecific binding sites. As a result, a novel ECL immunosensor was firstly obtained by applying the ECL of peroxydisulfate solution without conventional luminescent reagents. The AFP was determined in the range of 0.01-100 ng mL(-1), with a low detection limit of 3.3 pg mL(-1) (S/N=3). The proposed ECL immunosensor provides a rapid, simple, and sensitive immunoassay protocol for protein detection, which might hold a promise for clinical application. Moreover, this work would open up a new field in the application of peroxydisulfate solution ECL for highly sensitive bioassays.  相似文献   

11.
Quantum dots (QDs) have great promise in biological imaging, and as this promise is realized, there has been increasing interest in combining the benefits of QDs with those of other materials to yield composites with multifunctional properties. One of the most common materials combined with QDs is magnetic materials, either as ions (e.g. gadolinium) or as nanoparticles (e.g. superparamagnetic iron oxide nanoparticles, SPIONs). The fluorescent property of the QDs permits visualization, whereas the magnetic property of the composite enables imaging, magnetic separation, and may even have therapeutic benefit. In this review, the synthesis of fluorescent–magnetic nanoparticles, including magnetic QDs is explored; and the applications of these materials in imaging, separations, and theranostics are discussed. As the properties of these materials continue to improve, QDs have the potential to greatly impact biological imaging, diagnostics, and treatment.  相似文献   

12.
Helicobacter pylori is closely linked to many gastric diseases such as gastric ulcers and duodenal ulcers. Therefore, biosensing H. pylori has attracted wide attention from both scientists and clinicians. Here, we proposed an electrochemiluminescence (ECL)-based platform that could sensitively detect H. pylori DNA. In this platform, a novel target-cycling synchronized rolling circle amplification was used for signal amplification. Silver nanoclusters (Ag NCs) were synthesized on the circle DNA products, embedding them with the ability to catalyze the electrochemical reduction of K2S2O8, in turn resulting in rapid consumption of the ECL co-reactant near the working electrode, and leading to a decrease in the ECL emission intensity. In addition to its excellent stability and selectivity, the proposed strategy had a low detection limit of 10 pM, an indication that it can be beneficially applied to test biosamples. Furthermore, a biosensing chip was designed to improve the throughput and shed new light on large-scale clinical biosensing applications.  相似文献   

13.
A convenient and effective strategy for preparation nanohybrid film of multi-wall carbon nanotubes (MWNT) and gold colloidal nanoparticles (GNPs) by using proteins as linker is proposed. In such a strategy, hemoglobin (Hb) was selected as model protein to fabricate third-generation H2O2 biosensor based on MWNT and GNPs. Acid-pretreated, negatively charged MWNT was first modified on the surface of glassy carbon (GC) electrode, then, positively charged Hb was adsorbed onto MWNT films by electrostatic interaction. The {Hb/GNPs}n multilayer films were finally assembled onto Hb/MWNT film through layer-by-layer assembly technique. The assembly of Hb and GNPs was characterized with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM). The direct electron transfer of Hb is observed on Hb/GNPs/Hb/MWNT/GC electrode, which exhibits excellent electrocatalytic activity for the reduction of H2O2 to construct a third-generation mediator-free H2O2 biosensor. As compared to those H2O2 biosensors only based on carbon nanotubes, the proposed biosensor modified with MWNT and GNPs displays a broader linear range and a lower detection limit for H2O2 determination. The linear range is from 2.1x10(-7) to 3.0x10(-3) M with a detection limit of 8.0x10(-8) M at 3sigma. The Michaelies-Menten constant KMapp value is estimated to be 0.26 mM. Moreover, this biosensor displays rapid response to H2O2 and possesses good stability and reproducibility.  相似文献   

14.
A new metal-organic nanocomposite with synergistic catalysis function was prepared and developed to construct an electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of tumor biomarker CA125. Silver nanoparticles (AgNPs) and nicotinamide adenine dinucleotide hydride (NADH) that can participate and catalyze the ECL reaction of Ru(bpy)(3)(2+) were employed as the metal component and the organic component to synthesize the metal-organic nanocomposite of NADH-AgNPs (NA). The novel ECL immunosensor was assembled via Ru(bpy)(3)(2+)-doped silica nanoparticles (Ru-SiO(2)) modified electrode with the NA as immune labels. First, the chitosan-suspended Ru-SiO(2) nanoparticles were cast on the gold electrode surface to immobilize the ECL probes of Ru(bpy)(3)(2+) and link gold nanoparticles. Then, the primary antibodies were loaded onto the modified electrode via the gold sulfhydryl covalent binding. After immunobinding the analytes of antigen, NA-attached secondary antibodies could be captured as a sandwich type on the electrode. Finally, based on the circularly synergistic catalysis by the silver and NADH for the solid-phase ECL of Ru(bpy)(3)(2+), the proposed immunosensor sensed the concentration of antigen. The synergistic ECL catalysis of metal-organic nanocomposite amplified response signal and pushed the detection limit down to 0.03 U ml(-1), which initiated a new ECL labeling field and has great significance for ECL immunoassays.  相似文献   

15.
A simple general strategy was successfully developed for the preparation of magnetic–luminescent multifunctional nanocomposites by incorporating fluorescent (pyrene) and magnetic (Fe3O4) components simultaneously into a poly(styrene‐co‐methacrylic acid) [poly(St‐co‐MAA)] copolymer matrix. The nanospheres so prepared were characterized using scanning electron microscopy (SEM), powder X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The prepared magnetic–fluorescent inorganic–organic nanocomposites have excellent magnetic and photoluminescent properties. They can be used in magnetic separation of trace amounts of sample, fluorescence detection and imaging applications, including magnetic resonance imaging (MRI) and fluorescence imaging. The fluorescence quenching of the nanospheres in the presence of different amounts of Cu2+ ions was also investigated. Under optimal experimental conditions, the relative fluorescence intensity of the composite nanosphere colloidal solution is proportional to the concentration of Cu2+ ions, which indicates that these multifunctional nanocomposites can be used for the magnetic separation and fluorescence detection of Cu2+ ions. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

16.
Water‐soluble CdSe quantum dots (QDs) have been prepared by using L‐cysteine as the stabilizer in an aqueous phase under the optimized conditions. The characteristics and shapes of CdSe QDs have been proposed on the basis of UV‐Vis and fluorescence spectra. A rapid analytical method for electrochemiluminescence (ECL) determination of nitrite has been developed on the basis of the quenching effect on anodic ECL emission of CdSe QDs under the optimum experimental conditions. In a neutral system and at a relatively low potential (+0.960 V), the ECL emission of CdSe QDs could be greatly enhanced by sulfite and could be gradually quenched by nitrite at an indium tin oxide (ITO) electrode. The proposed method may allow the measurement of nitrite ranging from 1 μM to 0.5 mM with a correlation coefficient of 0.9956 (n = 10) and a detection limit of 0.2 μM (3σ), and the relative standard deviation for 10 μM nitrite (n = 9) is 1.72 %. The proposed method could be adopted for the sensitive detection of ECL quenchers by using nitrite as a model molecule. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

17.
We describe a non-labeled electrochemiluminescence (ECL) immunosensor based on CdSe quantum dots (QDs) for the detection of human prealbumin (PAB, antigen). The immunosensor was fabricated by layer by layer coupled with nanoparticle-amplification techniques. After two gold nanoparticle layers were self-assembled onto the gold electrode surface through cysteamine, anti-PAB (antibody) were conjugated with -COOH groups of both the CdSe QDs and cysteine, which were linked to the gold nanoparticle-modified electrode. The principle of ECL detection was that the immunocomplex inhibited the ECL reaction between CdSe QDs and K(2)S(2)O(8), which resulted in the decrease of ECL intensity. On the one hand, the immunocomplex increased the steric hindrance. On the other hand, the immunocomplex maybe inhibit the transfer of K(2)S(2)O(8) to the surface of the CdSe QD-electrode. The PAB concentration was determined in the range of 5.0 x 10(-10) to 1.0 x 10(-6) g mL(-1), and the detection limit was 1.0 x 10(-11) g mL(-1). The developed CdSe QD-based ECL immunosensor provides a rapid, simple, and sensitive immunoassay protocol for protein detection, which could be applied in more bioanalytical systems.  相似文献   

18.
Receptor coated resonant nanoparticles and quantum dots are proposed to provide a cellular-level resolution image of neural activities inside the brain. The functionalized nanoparticles and quantum dots in this approach will selectively bind to different neurotransmitters in the extra-synaptic regions of neurons. This allows us to detect neural activities in real time by monitoring the nanoparticles and quantum dots optically. Gold nanoparticles (GNPs) with two different geometries (sphere and rod) and quantum dots (QDs) with different sizes were studied along with three different neurotransmitters: dopamine, gamma-Aminobutyric acid (GABA), and glycine. The absorption/emission spectra of GNPs and QDs before and after binding of neurotransmitters and their corresponding receptors are reported. The results using QDs and nanorods with diameter 25nm and aspect rations larger than three were promising for the development of the proposed functional brain mapping approach.  相似文献   

19.
Herein, we describe a novel electrochemiluminescence (ECL) biosensor for protein kinase activities and inhibition monitoring based on the magnetic beads (MB) technology and signal enhancement of gold nanoparticles (GNP). In this design, ECL nanoprobes were prepared by conjugating GNP with phosphorylated DNA capture probes and tris-(2,2'-bipyridyl) ruthenium (TBR)-cysteamine. Zirconium cations, a specific bridging agent, mediate the linkage between biotin modified phosphorylated peptides and ECL nanoprobes. The complexes were then captured and enriched on the electrode surface by streptavidin-coated MB for ECL reaction. To confirm the feasibility of this biosensor, we employed protein kinase A (PKA) as the model kinase to validate the assay and a satisfactory detection limit of 0.005 U/mL was achieved. The combination of ECL and GNP lays a solid foundation for highly sensitive assay, meanwhile, the coupling of MB surfaces used for separation and capture with unmodified ECL electrode detection results in a greatly simplified and reusable protocol. Thus, our biosensor offers great promise for a highly sensitive and simple assay for protein kinase activity. Furthermore, the inhibition of PKA activity was monitored on the basis of the ECL signals change in response to the concentration of PKA inhibitor.  相似文献   

20.
A new electrochemical sensor based on a novel organic–inorganic material (PNFCTs) was proposed for detection of paracetamol in this paper. First, PNFCTs were prepared with multi-walled carbon nanotubes (MWNTs) and a derivative of 3,4,9,10-perylenetetracarboxylic dianhydride (PTC-NH2) via cross-linking method. Then, PNFCTs were coated onto the surface of the glassy carbon electrode (GCE) to form porous organic conducting polymer films (PNFCTs/GCE), which could not only increase the loading of paracetamol efficiently but also provide an interface with exceptional electrical conductivity for paracetamol. Finally, gold nanoparticles (GNPs) were attached to the electrode surface through electrodepositing method, which obtained GNPs/PNFCTs/GCE electrode. The electrochemical behavior of paracetamol on GNPs/PNFCTs/GCE was explored by cyclic voltammetrys (CVs) and differential pulse voltammograms (DPVs). The results showed that the GNPs/PNFCTs/GCE exhibited excellent electrocatalytic activity to paracetamol, which should be attributed to remarkable properties of the new composite nanomaterials with porous nanostructure and exceptional electrical conductivity. The wide liner range and detection limit were 0.3–575 and 0.1 μM, respectively. Finally, it was successfully used to detect paracetamol in dilution human serum and commercial tablets. The sensor shows great promise for simple, sensitive, and selective detection paracetamol and provides a promising approach in paracetamol clinical research and overdose diagnostic applications.  相似文献   

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