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Kun Wang - One of the best experts on this subject based on the ideXlab platform.

  • porous gold nanocages high atom utilization for thiolated aptamer immobilization to well balance the simplicity sensitivity and cost of disposable Aptasensors
    Analytical Chemistry, 2019
    Co-Authors: Chengquan Wang, Jing Qian, Kun Wang, Nan Hao, Qiaoshan Chen
    Abstract:

    Gold nanostructures such as nanospheres, nanorods, or nanowires have been extensively used for electrode surface modification because they not only can increase the overall electroactive surface but can also provide anchoring sites for thiolated aptamers through facile Au-S covalent bonds. However, all of those gold nanostructures used are solid and only the outer surface is attractive. In the aim to reduce the usage of precious gold, in this paper, porous gold nanocages (AuNCs) with both inner and outer walls for effective aptamer immobilization have been electrostatically adhered on a screen-printed carbon electrode (SPCE), to develop a highly sensitive aptasensor in a truly label-free manner. Specifically, the thiolated aptamers specific for aflatoxin B1 (AFB1) were chosen as the model aptamer and covalently bound to the inner and outer surface of AuNCs using Au-S chemistry. Exposing the sensing interface to targets could initiate the formation of the aptamer/target complex, resulting in an increased interfacial electron transfer resistance on the SPCE. Under optimal conditions, this aptasensor could detect AFB1 in a wide range of 0.1 pg mL-1 to 100 ng mL-1 with a high linear fit and has an ultralow detection limit of 0.03 pg mL-1 (S/N = 3). The developed aptasensor has remarkable merits such as simpler operation, more cost-effective, more sensitive, and less reagent consumption. We therefore provided a universal strategy to well balance the simplicity, sensitivity, and cost of disposable Aptasensors for a large population of targets having specific aptamer strands.

  • agbr nanoparticles 3d nitrogen doped graphene hydrogel for fabricating all solid state luminol electrochemiluminescence escherichia coli Aptasensors
    Biosensors and Bioelectronics, 2017
    Co-Authors: Nan Hao, Jing Qian, Qian Liu, Ying Zhang, Xuan Zhang, Zhou Zhou, Rong Hua, Kun Wang
    Abstract:

    It is necessary to develop rapid, simple and accurate detection method for Escherichia coli (E. coli) due to its widely distributed pathogenic bacteria. Herein, we prepared AgBr nanoparticles (NPs) anchored 3D nitrogen-doped graphene hydrogel (3DNGH) nanocomposites with an exceptionally large accessible surface by a simple hydrothermal approach. The as-prepared 3DNGH porous nanocomposite not only showed better conductivity than that of 3D graphene due to introducing nitrogen element into graphene framework, but also provided a high loading volume for immobilizing luminol. Meanwhile the anchored AgBr NPs served as the catalyst can effectively enhance the ECL behavior of luminol. And the resulting luminol/AgBr/3DNGH exhibited more excellent ECL performances, which was about 2, 3, 8 times enhanced respectively, comparing to luminol/AgBr/3DGH, luminol/3DNGH and luminol/AgBr/2DNG. Further, the multifunctional nanoarchitecture was used as the all-solid-state ECL platform for fabricating Escherichia coli Aptasensors via glutaraldehyde as crosslinking agent between amine-functionalized E. coli aptamer and luminol/AgBr/3DNGH. Based on the steric hindrance mechanism that E.coli can significantly decrease the ECL intensity, the proposed aptasensor displayed a linear response for E.coli in the range from 0.5 to 500 cfu/mL with an extremely low detection limit of 0.17 cfu/mL (S/N). In addition, this ECL aptasensor possessed great advantages including the simple operation process, low-cost and sensitivity, which provided a promising approach for the E.coli detection in biomedical, food detection and environmental analysis.

  • magnetic fluorescent targeting multifunctional aptasensorfor highly sensitive and one step rapid detection of ochratoxin a
    Biosensors and Bioelectronics, 2015
    Co-Authors: Chengquan Wang, Jing Qian, Kan Wang, Kun Wang, Qian Liu, Xiaoya Dong, Chengke Wang, Xingyi Huang
    Abstract:

    Abstract A multifunctional aptasensor for highly sensitive and one-step rapid detection of ochratoxin A (OTA), has been developed using aptamer-conjugated magnetic beads (MBs) as the recognition and concentration element and a heavy CdTe quantum dots (QDs) as the label. Initially, the thiolated aptamer was conjugated on the Fe 3 O 4 @Au MBs through Au–S covalent binding. Subsequently, multiple CdTe QDs were loaded both in and on a versatile SiO 2 nanocarrier to produce a large amplification factor of hybrid fluorescent nanoparticles (HFNPs) labeled complementary DNA (cDNA). The magnetic-fluorescent-targeting multifunctional aptasensor was thus fabricated by immobilizing the HFNPs onto MBs’ surface through the hybrid reaction between the aptamer and cDNA. This aptasensor can be produced at large scale in a single run, and then can be conveniently used for rapid detection of OTA through a one-step incubation procedure. The presence of OTA would trigger aptamer-OTA binding, resulting in the partial release of the HFNPs into bulk solution. After a simple magnetic separation, the supernatant liquid of the above solution contained a great number of CdTe QDs produced an intense fluorescence emission. Under the optimal conditions, the fluorescence intensity of the released HFNPs was proportional to the concentration of OTA in a wide range of 15 pg mL −1 –100 ng mL −1 with a detection limit of 5.4 pg mL −1 (S/N=3). This multifunctional aptasensor represents a promising path toward routine quality control of food safety, and also creates the opportunity to develop Aptasensors for other targets using this strategy.

  • amplified impedimetric aptasensor based on gold nanoparticles covalently bound graphene sheet for the picomolar detection of ochratoxin a
    Analytica Chimica Acta, 2014
    Co-Authors: Ling Jiang, Jing Qian, Kan Wang, Qian Liu, Xingwang Yang, Yuting Yan, Kun Wang
    Abstract:

    Abstract An amplified electrochemical impedimetric aptasensor for ochratoxin A (OTA) was developed with picomolar sensitivity. A facile route to fabricate gold nanoparticles covalently bound reduced graphene oxide (AuNPs–rGO) resulted in a large number of well-dispersed AuNPs on graphene sheets with tremendous binding sites for DNA, since the single rGO sheet and each AuNP can be loaded with hundreds of DNA strands. An aptasensor with sandwich model was fabricated which involved thiolated capture DNA immobilized on a gold electrode to capture the aptamer, then the sensing interface was incubated with OTA at a desired concentration, followed by AuNPs–rGO functionalized reporter DNA hybridized with the residual aptamers. By exploiting the AuNPs–rGO as an excellent signal amplified platform, a single hybridization event between aptamer and reporter DNA was translated into more than 10 7 redox events, leading to a substantial increase in charge-transfer resistance ( R ct ) by 7∼ orders of magnitude compared with that of the free aptamer modified electrode. Such designed aptasensor showed a decreased response of R ct to the increase of OTA concentrations over a wide range of 1 pg mL −1 –50 ng mL −1 and could detect extremely low OTA concentration, namely, 0.3 pg mL −1 or 0.74 pM, which was much lower than that of most other existed impedimetric Aptasensors. The signal amplification platform presented here would provide a promising model for the aptamer-based detection with a direct impedimetric method.

Tibor Hianik - One of the best experts on this subject based on the ideXlab platform.

  • electrochemical aptasensor based on polycarboxylic macrocycle modified with neutral red for aflatoxin b1 detection
    Electroanalysis, 2014
    Co-Authors: Gennady Evtugyn, Anna Porfireva, Veronika Stepanova, Rusal Sitdikov, Ivan I Stoikov, Dimitrios P Nikolelis, Tibor Hianik
    Abstract:

    Novel electrochemical Aptasensors based on glassy carbon electrodes modified with electropolymer- ized Neutral red and polycarboxylated macrocyclic li- gands onto which the DNA aptamers were covalently at- tached have been developed for detection of Aflatoxin B1 (AFB1). The interaction with an analyte resulted in the decrease of the cathodic peak current of the probe measured by CV and in the increase of the electron trans- fer resistance determined by EIS. The limit of detection was found to be 0.1 nM for CV and 0.05 nM for EIS methods, respectively. The aptasensor makes it possible to detect AFB1 in peanuts, cashew nuts, white wine and soy sauce with a recovery of 85-100 %.

  • Polyphenothiazine modified electrochemical aptasensor for detection of human α-thrombin
    Electroanalysis, 2007
    Co-Authors: Anna Porfirieva, Gennady Evtugyn, Tibor Hianik
    Abstract:

    QCM aptasensor for detection human thrombin has been developed on the base of polymeric forms of phenothiazine dyes, Methylene Blue and Methylene Green. Electrostatic accumulation of the analyte in the polyphenothiazine layer made it possible to increase the sensitivity of QCM detection of thrombin in comparison with bare gold electrodes coated with avidin or neutravidin. The influence of nonspecific binding of human serum albumin and the optimal composition of the surface layers were determined. The Aptasensors developed make it possible to detect 10-100 nM of thrombin. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.

Chengxiao Zhang - One of the best experts on this subject based on the ideXlab platform.

  • nanomaterial amplified signal off on electrogenerated chemiluminescence Aptasensors for the detection of thrombin
    Biosensors and Bioelectronics, 2010
    Co-Authors: Qiang Gao, Jia Yang, Chengxiao Zhang
    Abstract:

    Abstract Two electrogenerated chemiluminescence (ECL) Aptasensors for the detection of thrombin were developed using the thrombin binding aptamer (TBA) taken as a molecular recognition element and nanomaterial as a carrier of the ECL capture/signal probe. In the “signal off” aptasensor, the thiolated capture probe (ss-DNA, 12-mer) was self-assembled on the gold nanoparticles (GNPs) which were self-assembled on the surface of gold electrode, and hybridized with six-base segment of the ss-DNA sequence (Tgt-aptamer, 21-mer) containing TBA-I (ss-DNA, 15-mer) tagged with ruthenium complex, producing a high ECL intensity. Introduction of the analyte thrombin triggered the dissociation of the Tgt-aptamer tagged with ruthenium complex from the Aptasensors, led to significantly decrease in ECL intensity. The decreased ECL intensity was in proportion to the concentration of thrombin in a range from 2.7 × 10 −12 to 2.7 × 10 −9  M with a detection limit of 8 × 10 −13  M. In the “signal on” aptasensor, the thiolated TBA-I was self-assembled on the gold electrode for capturing thrombin onto the electrode and then the TBA-II (ss-DNA, 29-mer) labeled with single-walled carbon-nanotubes (SWNT)-ECL tag was bound with epitope of thrombin, producing a high ECL intensity. The increased ECL intensity was linearly with the concentration of thrombin from 1.0 × 10 −14  M to 1.0 × 10 −11  M with a detection limit of 3 × 10 −15  M. The present work demonstrates that using nanomaterial as a carrier for capture probe and signal probe is a promising way to amplify the ECL signal and to improve the sensitivity of the Aptasensors.

  • Nanomaterial-amplified "signal off/on" electrogenerated chemiluminescence Aptasensors for the detection of thrombin.
    Biosensors & bioelectronics, 2010
    Co-Authors: Qiang Gao, Jia Yang, Chengxiao Zhang
    Abstract:

    Abstract Two electrogenerated chemiluminescence (ECL) Aptasensors for the detection of thrombin were developed using the thrombin binding aptamer (TBA) taken as a molecular recognition element and nanomaterial as a carrier of the ECL capture/signal probe. In the “signal off” aptasensor, the thiolated capture probe (ss-DNA, 12-mer) was self-assembled on the gold nanoparticles (GNPs) which were self-assembled on the surface of gold electrode, and hybridized with six-base segment of the ss-DNA sequence (Tgt-aptamer, 21-mer) containing TBA-I (ss-DNA, 15-mer) tagged with ruthenium complex, producing a high ECL intensity. Introduction of the analyte thrombin triggered the dissociation of the Tgt-aptamer tagged with ruthenium complex from the Aptasensors, led to significantly decrease in ECL intensity. The decreased ECL intensity was in proportion to the concentration of thrombin in a range from 2.7 × 10 −12 to 2.7 × 10 −9  M with a detection limit of 8 × 10 −13  M. In the “signal on” aptasensor, the thiolated TBA-I was self-assembled on the gold electrode for capturing thrombin onto the electrode and then the TBA-II (ss-DNA, 29-mer) labeled with single-walled carbon-nanotubes (SWNT)-ECL tag was bound with epitope of thrombin, producing a high ECL intensity. The increased ECL intensity was linearly with the concentration of thrombin from 1.0 × 10 −14  M to 1.0 × 10 −11  M with a detection limit of 3 × 10 −15  M. The present work demonstrates that using nanomaterial as a carrier for capture probe and signal probe is a promising way to amplify the ECL signal and to improve the sensitivity of the Aptasensors.

Seyed Mohammad Taghdisi - One of the best experts on this subject based on the ideXlab platform.

  • Determination of microcystin-LR, employing Aptasensors.
    Biosensors & bioelectronics, 2018
    Co-Authors: Hasan Badie Bostan, Seyed Mohammad Taghdisi, Jenna L. Bowen, Nikolaos Demertzis, Ramin Rezaee, Yunes Panahi, Aristidis Tsatsakis, Gholamreza Karimi
    Abstract:

    Cyanobacteria produce toxins such as microcystin-LR (MC-LR), which are associated with potential hepatotoxicity in humans. The detection of cyanobacteria and their toxins in drinking water and sea food is therefore crucial. To date, methods such as high performance liquid chromatography (HPLC), protein phosphatase inhibition assay (PPIA), and Raman spectroscopy have been employed to monitor MC-LR levels. Although these techniques are precise and sensitive, they require expensive instrumentation, well-trained personnel and involve time-consuming processes meaning that their application is generally limited to well-resourced, centralised laboratory facilities. Among the emerging MC-LR detection methods, Aptasensors have received great attention because of their remarkable sensitivity, selectivity, and simplicity. Aptamers, also known as "chemical" or "artificial antibodies", serve as the recognition moieties in Aptasensors. This review explores the current state-of-the-art of MC-LR aptasensor platforms, evaluating the advantages and, limitations of typical transduction technologies to identify the most efficient detection system for the potentially harmful cyanobacteria associated toxin.

  • Ultrasensitive detection of ochratoxin A using Aptasensors.
    Biosensors & bioelectronics, 2017
    Co-Authors: Hasan Badie Bostan, Mohammad Ramezani, Khalil Abnous, Noor Mohammad Danesh, Gholamreza Karimi, Seyed Ali Mousavi Shaegh, Kazem Youssefi, Fahimeh Charbgoo, Seyed Mohammad Taghdisi
    Abstract:

    Regarding teratogenic, carcinogenic, and immunotoxic nature of ochratoxin A (OTA), selective and sensitive monitoring of this molecule in food samples is of great importance. In recent years, various methods have been introduced for detection of OTA. However, they are usually time-consuming, labor-intensive and expensive. Therefore, these parameters limited their usage. The emerging method of detection, aptasensor, has attracted more attention for OTA detection, due to distinctive advantages including high sensitivity, selectivity and simplicity. In this review, the new developed Aptasensors for detection of OTA have been investigated. We also highlighted advantages and disadvantages of different types of OTA Aptasensors. This review also takes into consideration the goal to find out which designs are the most rational ones for highly sensitive detection of OTA.

  • Optical and Electrochemical Aptasensors for Sensitive Detection of Streptomycin in Blood Serum and Milk.
    Methods in molecular biology (Clifton N.J.), 2017
    Co-Authors: Mohammad Ramezani, Khalil Abnous, Seyed Mohammad Taghdisi
    Abstract:

    Detection and quantitation of antibiotic residues in blood serum and foodstuffs are in great demand. We have developed Aptasensors for detection of streptomycin using electrochemical and optical methods. In the first method, an electrochemical aptasensor was developed for sensitive and selective detection of streptomycin, based on combination of exonuclease I (Exo I), complementary strand of aptamer (CS), arch shaped structure of aptamer (Apt)-CS conjugate, and gold electrode. The designed electrochemical aptasensor exhibited high selectivity toward streptomycin with a limit of detection (LOD) as low as 11.4 nM. Moreover, the developed electrochemical aptasensor was successfully used to detect streptomycin in milk and serum with LODs of 14.1 and 15.3 nM, respectively. In the second method, fluorescence quenching and colorimetric Aptasensors were designed for detection of streptomycin based on aqueous gold nanoparticles (AuNPs) and double-stranded DNA (dsDNA). In the absence of streptomycin, aptamer/FAM-labeled complementary strand dsDNA is stable, resulting in the aggregation of AuNPs by salt bridge and an obvious color change from red to blue and strong emission of fluorescence. The colorimetric and fluorescence quenching Aptasensors showed excellent selectivity toward streptomycin with limit of detections as low as 73.1 and 47.6 nM, respectively. The presented Aptasensors were successfully used to detect streptomycin in milk and serum. For serum, LODs were determined to be 58.2 and 102.4 nM for fluorescence quenching and colorimetric Aptasensors, respectively. For milk, LODs were calculated to be 56.2 and 108.7 nM for fluorescence quenching and colorimetric Aptasensors, respectively.

  • Aptasensors for quantitative detection of kanamycin
    Biosensors & bioelectronics, 2016
    Co-Authors: Rezvan Yazdian Robati, Mohammad Ramezani, Khalil Abnous, Atefeh Arab, Fatemeh Alebooye Langroodi, Seyed Mohammad Taghdisi
    Abstract:

    Up till now, various techniques have been developed to detect kanamycin in biological samples. However, due to some problems involved in these methods including time-consuming, expensive equipment and high consumption of reagents, new strategies for detection and quantitative determination of kanamycin are needed. Aptamer-based biosensors with unique recognition capability have attracted more attention of scientists because of its rapid response, high sensitivity and simple fabrication. Hence, we summarized optical and electrochemical kanamycin Aptasensors and focuses on recent advances and modern techniques in aptasensor-based kanamycin detection techniques in order to provide readers with an inclusive understanding of its improvement and progress.

Shaojun Dong - One of the best experts on this subject based on the ideXlab platform.

  • Homogeneous analysis: label-free and substrate-free Aptasensors.
    Chemistry an Asian journal, 2010
    Co-Authors: Shaojun Dong, Erkang Wang
    Abstract:

    In this Focus Review, we introduce a kind of "label-free" and "substrate-free" (LFSF) aptasensor that carries out the whole sensing process in a homogeneous solution. This means that commonly used covalent label; separation, and immobilization steps in biosensors are successfully avoided, which simplifies the sensing operations to the greatest degree. After brief description about the advantages of aptamers and "LFSF" Aptasensors, the main content of the review is divided into fluorescent aptasenors, calorimetric Aptasensors, and hemin-aptamer-DNAzyme "LFSF" Aptasensors, which are three most widely developed sensing systems in this field. It is hoped that this review can provide an overall scene about how aptamers function as ideal recognition elements in smart analysis.

  • Solid-state probe based electrochemical aptasensor for cocaine: A potentially convenient, sensitive, repeatable, and integrated sensing platform for drugs
    Analytical Chemistry, 2010
    Co-Authors: Yan Du, Jianyuan Yin, Chaogui Chen, Bingling Li, Shaojun Dong, Ming Zhou, Erkang Wang
    Abstract:

    Aptamers, which are artificial oligonucleotides selected in vitro, have been employed to design novel biosensors (i.e., Aptasensors). In this work, we first constructed a label-free electrochemical aptasensor introducing a probe immobilization technique by the use of a layer-by-layer (LBL) self-assembled multilayer with ferrocene-appended poly(ethyleneimine) (Fc-PEI) on an indium tin oxide (ITO) array electrode for detection of cocaine. The Fc-PEI and gold nanoparticles (AuNPs) were LBL assembled on the electrode surface via electrostatic interaction. Then, cocaine aptamer fragments, SH-C2, were covalently labeled onto the outermost AuNP layer. When the target cocaine and cocaine aptamer C1 were present simultaneously, the SH-C2 layer hybridized partly with C1 to bind the cocaine, which led to a decreased differential pulse voltammetry (DPV) signal of Fc-PEI. This DPV signal change could be used to sensitively detect cocaine with the lowest detectable concentration down to 0.1 microM and the detection range up to 38.8 microM, which falls in the the expected range for medical use of detecting drug abuse involving cocaine. Meanwhile, the sensor was specific to cocaine in complex biologic fluids such as human plasma, human saliva, etc. The sensing strategy had general applicability, and the detection of thrombin could also be realized, displayed a low detection limit, and exhibited worthiness to other analytes. The aptasensor based on the array electrode held promising potential for integration of the sensing ability in multianalysis for simultaneous detection.

  • amplified electrochemical aptasensor taking aunps based sandwich sensing platform as a model
    Biosensors and Bioelectronics, 2008
    Co-Authors: Yuling Wang, Hui Wei, Shaojun Dong
    Abstract:

    Here, we report a sensitive amplified electrochemical impedimetric aptasensor for thrombin, a kind of serine protease that plays important role in thrombosis and haemostasis. For improving detection sensitivity, a sandwich sensing platform is fabricated, in which the thiolated aptamers are firstly immobilized on a gold substrate to capture the thrombin molecules, and then the aptamer functionalized Au nanoparticles (AuNPs) are used to amplify the impedimetric signals. Such designed aptamer/thrombin/AuNPs sensing system could not only improve the detection sensitivity compared to the reported impedimetric Aptasensors but also provide a promising signal amplified model for aptamer-based protein detection. In this paper, we realize a sensitive detection limit of 0.02 nM, with a linear range of 0.05-18 nM. Meanwhile, the effect of 6-mercaptohexanol (MCH) and 2-mercaptoethanol (MCE) on the modification of the electrode is investigated.