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https://www.readbyqxmd.com/read/28738658/an-ultrasensitive-chemiluminescence-aptasensor-for-thrombin-detection-based-on-iron-porphyrin-catalyzing-luminescence-desorbed-from-chitosan-modified-magnetic-oxide-graphene-composite
#1
Yuanling Sun, Yanhui Wang, Jianbo Li, Chaofan Ding, Yanna Lin, Weiyan Sun, Chuannan Luo
In this work, an ultrasensitive chemiluminescence (CL) aptasensor was prepared for thrombin detection based on iron porphyrin catalyzing luminol - hydrogen peroxide luminescence under alkaline conditions, and iron porphyrin was desorbed from chitosan modified magnetic oxide graphene composite (CS@Fe3O4@GO). Firstly, CS@Fe3O4@GO was prepared. CS@Fe3O4@GO has advantages of the good biocompatibility and positively charged on its surface of CS, the large specific surface area of GO and the easy separation characteristics of Fe3O4...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738645/competitive-fluorescence-anisotropy-polarization-assay-for-atp-using-aptamer-as-affinity-ligand-and-dye-labeled-atp-as-fluorescence-tracer
#2
Yapiao Li, Linlin Sun, Qiang Zhao
We developed an aptamer-based competitive fluorescence anisotropy (FA)/fluorescence polarization (FP) assay for adenosine triphosphate (ATP). Different from the traditional fluorescence polarization immunoassays for small molecules, here DNA aptamer against ATP was used as affinity ligand, and tetramethylrhodamine (TMR) labeled ATP served as fluorescent tracer. The binding between TMR-labeled ATP and aptamer gave large FA due to molecular volume increase and restricted rotation of the dye-labeled ATP. When ATP was added in solution, ATP competitively displaced the TMR-labeled ATP from aptamer affinity complex, causing decrease of FA of TMR-labeled ATP...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738631/a-review-aptamer-based-analytical-strategies-using-the-nanomaterials-for-environmental-and-human-monitoring-of-toxic-heavy-metals
#3
REVIEW
Leila Farzin, Mojtaba Shamsipur, Shahab Sheibani
Recent developments in biotechnology offer the new methods for the sensitive detection of heavy metals based on the affinity and specificity of aptamers, as nucleic acid ligands selected from random sequence pools in vitro. Heavy metals have received considerable importance as the most toxic metallic pollutants which may cause serious environmental damages. They are classified as trace elements because of their presence in trace concentrations in various environmental matrices. Thus, the precise and sensitive methods to detect heavy metals are important to ensure human and environment safety...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738618/high-sensitivity-surface-plasmon-resonance-biosensor-for-detection-of-microrna-and-small-molecule-based-on-graphene-oxide-gold-nanoparticles-composites
#4
Qing Li, Qing Wang, Xiaohai Yang, Kemin Wang, Hua Zhang, Wenyan Nie
A versatile and sensitive surface plasmon resonance (SPR) biosensor based on two layers of graphene oxide-gold nanoparticles (GO-AuNPs) composites was designed for the detection of microRNA (miRNA) and small molecule adenosine. The bottom layer, which acted as a functionalized substrate on the sensor chip, provided a high specific surface area convenient for the immobilization of capture DNA molecules. The upper layer served as a signal-amplification element. By employing these two layers of GO-AuNPs composites, the dual amplification strategy was achieved so that a measurement of miRNA-141 with a detection limit of 0...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738067/the-prediction-of-late-onset-preeclampsia-results-from-a-longitudinal-proteomics-study
#5
Offer Erez, Roberto Romero, Eli Maymon, Piya Chaemsaithong, Bogdan Done, Percy Pacora, Bogdan Panaitescu, Tinnakorn Chaiworapongsa, Sonia S Hassan, Adi L Tarca
BACKGROUND: Late-onset preeclampsia is the most prevalent phenotype of this syndrome; nevertheless, only a few biomarkers for its early diagnosis have been reported. We sought to correct this deficiency using a high through-put proteomic platform. METHODS: A case-control longitudinal study was conducted, including 90 patients with normal pregnancies and 76 patients with late-onset preeclampsia (diagnosed at ≥34 weeks of gestation). Maternal plasma samples were collected throughout gestation (normal pregnancy: 2-6 samples per patient, median of 2; late-onset preeclampsia: 2-6, median of 5)...
2017: PloS One
https://www.readbyqxmd.com/read/28735043/a-high-sensitivity-electrochemical-aptasensor-of-carcinoembryonic-antigen-based-on-graphene-quantum-dots-ionic-liquid-nafion-nanomatrix-and-dnazyme-assisted-signal-amplification-strategy
#6
Jing-Yi Huang, Lang Zhao, Wan Lei, Wei Wen, Yi-Jia Wang, Ting Bao, Hua-Yu Xiong, Xiu-Hua Zhang, Sheng-Fu Wang
In this work, we have developed an electrochemical aptasensor for high-sensitivity determination of carcinoembryonic antigen (CEA) based on lead ion (Pb(2+))-dependent DNAzyme-assisted signal amplification and graphene quantum dot-ionic liquid-nafion (GQDs-IL-NF) composite film. We designed hairpin DNA containing CEA-specific aptamers and DNAzyme chains. In the presence of CEA, hairpin DNA recognized the target and performed a DNAzyme-assisted signal amplification reaction to yield a large number of single-stranded DNA...
July 15, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28734049/development-of-aptamers-against-unpurified-proteins
#7
Shinichi Goto, Kaori Tsukakoshi, Kazunori Ikebukuro
SELEX (Systematic Evolution of Ligands by EXponential enrichment) has been widely used for the generation of aptamers against target proteins. However, its requirement for pure target proteins remains a major problem in aptamer selection, as procedures for protein purification from crude bio-samples are not only complicated but also time and labour consuming. This is because native proteins can be found in a large number of diverse forms because of posttranslational modifications and their complicated molecular conformations...
July 22, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28732346/multiplexed-aptasensor-for-simultaneous-detection-of-carcinoembryonic-antigen-and-mucin-1-based-on-metal-ion-electrochemical-labels-and-ru-nh3-6-3-electronic-wires
#8
Chao Ma, Haiyun Liu, Lina Zhang, Hao Li, Mei Yan, Xianrang Song, Jinghua Yu
In this paper, a dual-target electrochemical aptasensor has been developed for simultaneous detection of carcinoembryonic antigen and mucin-1 based on metal ion electrochemical labels and Ru(NH3)6(3+) electronic wires. When targets are present, the interaction between targets and their respective aptamers leads to the dissociation of double-strand DNA because the targets have higher affinity to its aptamer than the complementary strand. And the qualitative and quantitative analyses of the two targets are realized by the differential pulse voltammetry (DPV) peaks generated by metal ion electrochemical labels...
July 13, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28732094/surface-enhanced-raman-spectroscopy-competitive-binding-biosensor-development-utilizing-surface-modification-of-silver-nanocubes-and-a-citrulline-aptamer
#9
Brian M Walton, George W Jackson, Nicolaas Deutz, Gerard Cote
No abstract text is available yet for this article.
July 1, 2017: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/28731107/a-fluorescent-turn-on-nanoprobe-for-simultaneous-visualization-of-dual-targets-involved-in-cell-apoptosis-and-drug-screening-in-living-cells
#10
Xiaolong Zhang, Naishun Liao, Geng Chen, Aixian Zheng, Yongyi Zeng, Xiaolong Liu, Jingfeng Liu
Herein, a novel dual-responsive two-color fluorescent nanoprobe has been designed for the fluorescence activation imaging of cell apoptosis in living cells. The nanoprobe consists of a gold nanoparticle core functionalized with a dense layer of DNA aptamers and peptides, which shows high affinity and specific response to cytochrome c (Cyt c) and caspase-3, respectively. The formation of the aptamer-Cyt c complex and the cleavage of the specific peptide by caspase-3 can liberate the dye labelled aptamers and peptides from the surface of gold nanoparticles, and then recover their fluorescence...
July 21, 2017: Nanoscale
https://www.readbyqxmd.com/read/28730439/design-and-preparation-of-aptamer-sirna-chimeras-asics-for-targeted-cancer-therapy
#11
Sven Kruspe, Paloma H Giangrande
Conjugation of cell-internalizing DNA or RNA aptamers to tumor-suppressing siRNAs represents a novel promising approach for cancer therapy. Here we describe how to employ RNA aptamers that bind to cell surface receptors as carriers for cell-targeted siRNA (or miRNA) delivery. This protocol was optimized to improve the efficiency of the aptamer-siRNA/miRNA conjugates and facilitate its implementation in most molecular biology labs. The single working steps include (1) outlining the optimal sequences of the RNA strands bearing the aptamer and siRNA sequence, for which further (2) a dsDNA template is synthesized and then (3) transcribed into an RNA that will be (4) folded and annealed to a chemically synthesized siRNA complementary strand...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28730438/x-aptamer-selection-and-validation
#12
Ganesh L Lokesh, Hongyu Wang, Curtis H Lam, Varatharasa Thiviyanathan, Nancy Ward, David G Gorenstein, David E Volk
Aptamers and second generation analogs, such as X-Aptamers (XAs), SOMAmers, locked nucleic acids (LNAs), and others are increasingly being used for molecular pathway targeting, biomarker discovery, or disease diagnosis by interacting with protein targets on the surface of cells or in solution. Such targeting is being used for imaging, diagnostic evaluation, interference of protein function, or delivery of therapeutic agents. Selection of aptamers using the original SELEX method is cumbersome and time-consuming, often requiring 10-15 rounds of selection, and provides aptamers with a limited number of functional groups, namely four bases of DNA or RNA, although newer SELEX methods have increased this diversity...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28730434/cotranscriptional-production-of-chemically-modified-rna-nanoparticles
#13
Maria L Kireeva, Kirill A Afonin, Bruce A Shapiro, Mikhail Kashlev
RNA nanoparticles consisting of multiple RNA strands of different sequences forming various three-dimensional structures emerge as promising carriers of siRNAs, RNA aptamers, and ribozymes. In vitro transcription of a mixture of dsDNA templates encoding all the subunits of the RNA nanoparticle may result in cotranscriptional self-assembly of the nanoparticle. Based on our experience with production of RNA nanorings, RNA nanocubes, and RNA three-way junctions, we propose a strategy for optimization of the cotranscriptional production of chemically modified ribonuclease-resistant RNA nanoparticles...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28730311/aptamer-based-fluorescence-quenching-lateral-flow-strip-for-rapid-detection-of-mercury-ii-ion-in-water-samples
#14
Ze Wu, Haicong Shen, Junhui Hu, Qiangqiang Fu, Cuize Yao, Shiting Yu, Wei Xiao, Yong Tang
Divalent mercury ion (Hg(2+)) is one of the most common and stable forms of mercury pollution. In this study, a skillfully designed lateral flow strip (LFS) was developed for sensitive detection of Hg(2+) in river water samples. Aptamer, a specific oligonucleotide probe, was used to selectively identify and target Hg(2+) instead of antibody in traditional immunechromatographic strips; and the fluorescence-quenching system was used to generate positive and low background florescence signals in the competitive-likely LFS...
July 20, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28729901/aptamer-functionalized-neural-recording-electrodes-for-the-direct-measurement-of-cocaine-in-vivo
#15
I Mitch Taylor, Zhanhong Du, Emma T Bigelow, James R Eles, Anthony R Horner, Kasey A Catt, Stephen G Weber, Brian G Jamieson, X Tracy Cui
Cocaine is a highly addictive psychostimulant that acts through competitive inhibition of the dopamine transporter. In order to fully understand the region specific neuropathology of cocaine abuse and addiction, it is unequivocally necessary to develop cocaine sensing technology capable of directly measuring real-time cocaine transient events local to different brain regions throughout the pharmacokinetic time course of exposure. We have developed an electrochemical aptamer-based in vivo cocaine sensor on a silicon based neural recording probe platform capable of directly measuring cocaine from discrete brain locations using square wave voltammetry (SWV)...
April 7, 2017: Journal of Materials Chemistry. B, Materials for Biology and Medicine
https://www.readbyqxmd.com/read/28728963/structural-principles-of-fluorescent-rna-aptamers
#16
REVIEW
Robert J Trachman, Lynda Truong, Adrian R Ferré-D'Amaré
Several aptamer RNAs have been selected in vitro that bind to otherwise weakly fluorescent small molecules and enhance their fluorescence several thousand-fold. By genetically tagging cellular RNAs of interest with these aptamers and soaking cells in their cell-permeable cognate small-molecule fluorophores, it is possible to use them to study RNA localization and trafficking. These aptamers have also been fused to metabolite-binding RNAs to generate fluorescent biosensors. The 3D structures of three unrelated fluorogenic RNAs have been determined, and reveal a shared reliance on base quadruples (tetrads) to constrain the photo-excited chromophore...
July 17, 2017: Trends in Pharmacological Sciences
https://www.readbyqxmd.com/read/28728900/ultra-sensitive-aptasensor-based-on-a-gqd-nanocomposite-for-detection-of-hepatitis-c-virus-core-antigen
#17
Kazhal Ghanbari, Mahmoud Roushani, Azadeh Azadbakht
In the present study, by using the aptamer proximity binding assay strategy, a novel electrochemical aptasensor is described for ultrasensitive detection of hepatitis C virus (HCV) core antigen. The immobilization surface is prepared by the modification of a glassy carbon electrode (GCE) with a graphene quantum dots (GQD). GQD were introduced as a novel and suitable substrate for aptamers through π-π stacking interactions, the richness of hydrophilic edges as well as hydrophobic plane in GQD which enhances the aptamer absorption on the electrode surface...
July 17, 2017: Analytical Biochemistry
https://www.readbyqxmd.com/read/28728009/bridged-rebar-graphene-functionalized-aptasensor-for-pathogenic-e-coli-o78-k80-h11-detection
#18
Harmanjit Kaur, Munish Shorie, Manju Sharma, Ashok K Ganguli, Priyanka Sabherwal
We report a novel fabrication method of functionalised Bridged Rebar Graphene (BRG) onto newly designed nanostructured aptasensor for label free impedimetric sensing of pathogenic bacteria E. coli O78:K80:H11. The chemical facilitated unscrolling of MWCNT and subsequent bridging with terephthalaldehyde (TPA) to form 3D-hierarchical BRG nanoconstruct exhibited synergistic effect by combining enhanced electrical properties and facile chemical functionality for stable bio-interface. The bacteria-DNA interactions were captured on BRG nanostructured electrode by using specific anti-E...
July 5, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28727998/enrichment-of-endogenous-fractalkine-and-anti-inflammatory-cells-via-aptamer-functionalized-hydrogels
#19
Syed Faaiz Enam, Jack R Krieger, Tarun Saxena, Brian E Watts, Claire E Olingy, Edward A Botchwey, Ravi V Bellamkonda
Early recruitment of non-classical monocytes and their macrophage derivatives is associated with augmented tissue repair and improved integration of biomaterial constructs. A promising therapeutic approach to recruit these subpopulations is by elevating local concentrations of chemoattractants such as fractalkine (FKN, CX3CL1). However, delivering recombinant or purified proteins is not ideal due to their short half-lives, suboptimal efficacy, immunogenic potential, batch variabilities, and cost. Here we report an approach to enrich endogenous FKN, obviating the need for delivery of exogenous proteins...
July 10, 2017: Biomaterials
https://www.readbyqxmd.com/read/28724889/aptamer-mediated-survivin-rnai-enables-5-fluorouracil-to-eliminate-colorectal-cancer-stem-cells
#20
Hadi AlShamaileh, Tao Wang, Dongxi Xiang, Wang Yin, Phuong Ha-Lien Tran, Roberto A Barrero, Pei-Zhuo Zhang, Yong Li, Lingxue Kong, Ke Liu, Shu-Feng Zhou, Yingchun Hou, Sarah Shigdar, Wei Duan
The development of chemoresistance and inability in elimination of cancer stem cells are among the key limitations of cancer chemotherapy. Novel molecular therapeutic strategies able to overcome such limitations are urgently needed for future effective management of cancer. In this report, we show that EpCAM-aptamer-guided survivin RNAi effectively downregulated survivin both in colorectal cancer cells in vitro and in a mouse xenograft model for colorectal cancer. When combined with the conventional chemotherapeutic agents, the aptamer-guided survivin RNAi was able to enhance the sensitivity towards 5-FU or oxaliplatin in colorectal cancer stem cells, increase apoptosis, inhibit tumour growth and improve the overall survival of mice bearing xenograft colorectal cancer...
July 19, 2017: Scientific Reports
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