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Aptamers

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https://www.readbyqxmd.com/read/29778001/patchy-gold-coated-fe-3-o-4-nanospheres-with-enhanced-catalytic-activity-applied-for-paper-based-bipolar-electrode-electrochemiluminescence-aptasensors
#1
Xin Zhang, Ning Bao, Xiliang Luo, Shou-Nian Ding
In this work, novel multifunctional patchy gold coated Fe3 O4 hybrid nanoparticles (PG-Fe3 O4 NPs) have been successfully synthesized in aqueous medium via a facile adsorption-reduction method. A rational formation mechanism has been proposed by monitoring the morphological evolution. The PG-Fe3 O4 NPs retained the good magnetic property and exhibited excellent catalytical effeciency towards the electrochemical reduction of hydrogen peroxide. Chronoamperometric and amperometric experiments indicated a relatively high catalytic rate constant of 3...
May 10, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29777816/aptamer-based-assay-for-monitoring-genetic-disorder-phenylketonuria-pku
#2
Mohammad Hasanzadeh, Amir Zargami, Hossein Navay Baghban, Ahad Mokhtarzadeh, Nasrin Shadjou, Soltanali Mahboob
The genetic disorder phenylketonuria (PKU) is the inability to metabolize phenylalanine because of a lack of the enzyme phenylalanine hydroxylase. Phenylalanine is used to biochemically form proteins, coded for by DNA. The development of an apta-assay for detection of l-Phenylalanine is presented in this work. A highly specific DNA-aptamer, selected to l-Phenylalanine was immobilized onto a gold nanostructure and electrochemical measurements were performed in a solution containing the phosphate buffer solution with physiological pH...
May 16, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29777679/development-of-dnazyme-based-pcr-signal-cascade-amplification-for-visual-detection-of-listeria-monocytogenes-in-food
#3
Zhanmin Liu, Chenhui Yao, Cuiyun Yang, Yanming Wang, Sibao Wan, Junyi Huang
Listeria monocytogenes is an important food-borne pathogen, and it can cause severe diseases. Rapid detection of L. monocytogenes is crucial to control this pathogen. A simple and robust strategy based on the cascade of PCR and G-quadruplex DNAzyme catalyzed reaction was used to detect L. monocytogenes. In the presence of hemin and the aptamer formed during PCR, the catalytic horseradish peroxidase-mimicking G-quadruplex DNAzymes allow the colorimetric responses of target DNA from L. monocytogenes. This assay can detect genomic DNA of L...
May 16, 2018: Analytical Biochemistry
https://www.readbyqxmd.com/read/29777309/fluorometric-determination-of-vibrio-parahaemolyticus-using-an-f-0-f-1-atpase-based-aptamer-and-labeled-chromatophores
#4
Nuo Duan, Shijia Wu, Huiling Zhang, Ying Zou, Zhouping Wang
An F0 F1 -ATPase-based aptasensor is described for the fluorometric determination of Vibrio parahaemolyticus. Chromatophores containing F0 F1 -ATPases were first prepared from Rhodospirillum rubrum cells. Then, an aptamer-functionalized chromatophore acts as the capture probe, and a chromatophore labeled with the pH probe fluorescein acts as the signalling probe. In the presence of V. parahaemolyticus, the rotation rate of F0 F1 -ATPase is decreased due to the formation of the aptamer-chromatophore complex...
May 18, 2018: Mikrochimica Acta
https://www.readbyqxmd.com/read/29775720/diagnosing-human-blood-clotting-deficiency
#5
REVIEW
Chong Cheen Ong, Subash C B Gopinath, Leong Wei Xian Rebecca, Veeradasan Perumal, Thangavel Lakshmipriya, Mohamed Shuaib Mohamed Saheed
There are different clotting factors present in blood, carries the clotting cascade and excessive bleeding may cause a deficiency in the clotting. Diagnosis of deficiency in clotting reduces the potential fatality. For enabling a sensor to detect the clotting factors, suitable probes such as antibody and aptamer have been used to capture the clotting factors on the sensing surface. Two major clotting factors were widely studied in detail for the diagnosis of clotting deficiency, which includes factor IX and thrombin...
May 15, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29775052/double-photosystems-based-z-scheme-photoelectrochemical-sensing-mode-for-ultrasensitive-detection-of-disease-biomarker-accompanying-3d-dna-walker
#6
Shuzhen Lv, Kangyao Zhang, Yongyi Zeng, Dianping Tang
A new double photosystems-based 'Z-scheme' photoelectrochemical (PEC) sensing platform is designed for ultrasensitive detection of prostate-specific antigen (PSA) by coupling with three-dimensional (3D) DNA walker. Two photosystems consist of CdS quantum dots (photosystem I; PS I) and BiVO4 photoactive materials (photosystem II; PS II), whereas gold nanoparticles (AuNPs) photodeposited on high-active {010} facets of BiVO4 are used as the electron mediators to promote electron transfer from conduction band (CB) of PS II to valence band (VB) of PS I...
May 18, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29774900/multiplex-detection-of-quality-indicator-molecule-targets-in-urine-using-programmable-hairpin-probes-based-on-a-simple-double-t-type-microchip-electrophoresis-platform-and-isothermal-polymerase-catalyzed-target-recycling
#7
Lingying Zhou, Ning Gan, Yongxiang Wu, Futao Hu, Jianyuan Lin, Yuting Cao, Dazhen Wu
Recently, it has been crucial to be able to detect and quantify small molecular targets simultaneously in biological samples. Herein, a simple and conventional double-T type microchip electrophoresis (MCE) based platform for the multiplex detection of quality indicator molecule targets in urine, using ampicillin (AMPI), adenosine triphosphate (ATP) and estradiol (E2) as models, was developed. Several programmable hairpin probes (PHPs) were designed for detecting different targets and triggering isothermal polymerase-catalyzed target recycling (IPCTR) for signal amplification...
May 18, 2018: Analyst
https://www.readbyqxmd.com/read/29774421/a-fluorometric-aptasensor-for-methamphetamine-based-on-fluorescence-resonance-energy-transfer-using-cobalt-oxyhydroxide-nanosheets-and-carbon-dots
#8
Zeinab Saberi, Behzad Rezaei, Hossein Faroukhpour, Ali Ashghar Ensafi
Cobalt oxyhydroxide (CoOOH) nanosheets are efficient fluorescence quenchers due to their specific optical properties and high surface area. The combination of CoOOH nanosheets and carbon dots (CDs) has not been used in any aptasensor based on fluorescence quenching so far. An aptamer based fluorometric assay is introduced that is making use of fluorescent CDs conjugated to the aptamer against methamphetamine (MTA), and of CoOOH nanosheets which reduce the fluorescence of the CDs as a quencher. The results revealed that the conjugated CDs with aptamers were able to enclose the CoOOH nanosheets...
May 17, 2018: Mikrochimica Acta
https://www.readbyqxmd.com/read/29772170/supramolecularly-engineered-circular-bivalent-aptamer-for-enhanced-functional-protein-delivery
#9
Ying Jiang, Xiaoshu Pan, Jin Chang, Weijia Niu, Weijia Hou, Hailan Kuai, Zilong Zhao, Ji Liu, Ming Wang, Weihong Tan
Circular bivalent aptamers (cb-apt) comprise an emerging class of chemically engineered aptamers with substantially improved stability and molecular recognition ability. Its therapeutic application, however, is challenged by the lack of functional modules to control the interactions of cb-apt with therapeutics. We present the design of a β-cyclodextrin-modified cb-apt (cb-apt-βCD) and its supramolecular interaction with molecular therapeutics via host-guest chemistry for targeted intracellular delivery. The supramolecular ensemble exhibits high serum stability and enhanced intracellular delivery efficiency compared to a monomeric aptamer...
May 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29770378/selection-and-characterization-of-a-dna-aptamer-to-crystal-violet
#10
Yang Chen, Jine Wang, Yajie Zhang, Lijun Xu, Tian Gao, Bing Wang, Renjun Pei
Aptamers are short single-stranded DNA or RNA, which can be selected in vitro by systematic evolution of ligands by exponential enrichment (SELEX). In order to develop novel light-up probes to substitute G-quadruplex (G4), we selected a DNA aptamer for crystal violet (CV), a triphenylmethane light-up dye, by a modified affinity chromatography-based SELEX. The ssDNA pool was first coupled on streptavidin-coated agarose beads through a biotin labeled complementary oligonucleotide, and then the aptamer sequences would be released from agarose beads by CV affinity...
May 17, 2018: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/29769643/aptamer-effective-in-vivo
#11
Clemens Thoma
No abstract text is available yet for this article.
May 16, 2018: Nature Reviews. Urology
https://www.readbyqxmd.com/read/29768001/crystal-structures-of-the-mango-ii-rna-aptamer-reveal-heterogeneous-fluorophore-binding-and-guide-engineering-of-variants-with-improved-selectivity-and-brightness
#12
Robert Trachman, Amir Abdolahzadeh, Alessio Andreoni, Razvan Cojocaru, Jay R Knutson, Michaël Ryckelynck, Peter John Unrau, Adrian Ferré-D'Amaré
Several RNA aptamers that bind small molecules and enhance their fluorescence have been successfully used to tag and track RNAs in vivo, but these genetically encodable tags have not yet achieved single-fluorophore resolution. Recently, Mango-II, an RNA that binds TO1-Biotin with ~1 nM affinity and enhances its fluorescence by >1,500-fold was isolated by fluorescence selection from the pool that yielded the original RNA Mango. We determined the crystal structures of Mango-II in complex with two fluorophores, TO1-Biotin and TO3-Biotin, and found that despite their high affinity, the ligands adopt multiple distinct conformations, indicative of a binding pocket with modest stereoselectivity...
May 16, 2018: Biochemistry
https://www.readbyqxmd.com/read/29766180/a-nitrocellulose-membrane-based-integrated-microfluidic-system-for-bacterial-detection-utilizing-magnetic-composite-membrane-microdevices-and-bacteria-specific-aptamers
#13
Jia-Han Wu, Chih-Hung Wang, Yu-Dong Ma, Gwo-Bin Lee
Bacteria such as Acinetobacter baumannii (AB) can cause serious infections, resulting in high mortality if not diagnosed early and treated properly; there is consequently a need for rapid and accurate detection of this bacterial species. Therefore, we developed a new, nitrocellulose-based microfluidic system featuring AB-specific aptamers capable of automating the bacterial detection process via the activity of microfluidic devices composed of magnetic-composite membranes. Electromagnets were used to actuate these microfluidic devices such that the entire diagnostic process could be conducted in the integrated microfluidic system within 40 minutes with a limit of detection as low as 450 CFU per reaction for AB...
May 16, 2018: Lab on a Chip
https://www.readbyqxmd.com/read/29765515/cancer-cell-selective-clathrin-mediated-endocytosis-of-aptamer-decorated-nanoparticles
#14
Shira Engelberg, Julia Modrejewski, Johanna G Walter, Yoav D Livney, Yehuda G Assaraf
Lung cancer is the leading cause of cancer mortality worldwide, resulting in 88% deaths of all diagnosed patients. Hence, novel therapeutic modalities are urgently needed. Single-stranded oligonucleotide-based aptamers (APTs) are excellent ligands for tumor cell targeting. However, the molecular mechanisms underlying their internalization into living cells have been poorly studied. Towards the application of APTs for active drug targeting to cancer cells, we herein studied the mechanism underlying S15-APT internalization into human non-small cell lung cancer A549 cells...
April 20, 2018: Oncotarget
https://www.readbyqxmd.com/read/29764582/-research-advances-in-the-role-of-aptamers-in-the-diagnosis-and-targeted-therapy-of-pediatric-cancer
#15
Yi-Bin Zhang, Yan-Peng Wang, Jing Liu
Aptamers are single-stranded DNA or RNA which are isolated from synthesized random oligonucleotide library in vitro via systematic evolution of ligands by exponential enrichment (SELEX) and can bind to metal ions, small molecules, carbohydrates, lipids, proteins, and others targets with high affinity and specificity. Aptamers have the advantages of simple preparation, good thermal stability, and low immunogenicity and have great potential in the medical fields such as molecular imaging, biosensing, early diagnosis of diseases, and targeted therapy...
May 2018: Zhongguo Dang Dai Er Ke za Zhi, Chinese Journal of Contemporary Pediatrics
https://www.readbyqxmd.com/read/29762016/rapid-2-ms-interrogation-of-electrochemical-aptamer-based-sensor-response-using-intermittent-pulse-amperometry
#16
Mirelis Santos-Cancel, Robert Alexander Lazenby, Ryan J White
In this manuscript, we employ the technique intermittent pulse amperometry (IPA) to interrogate equilibrium and kinetic target binding to the surface of electrochemical, aptamer-based (E-AB) sensors, achieving as fast as 2 ms time resolution. E-AB sensors comprise an electrode surface modified with a flexible nucleic acid aptamer tethered at the 3'-terminus with a redox-active molecule. The introduction of a target changes the conformation and flexibility of the nucleic acid which alters the charge transfer rate of the appended redox molecule...
May 15, 2018: ACS Sensors
https://www.readbyqxmd.com/read/29759234/label-free-aptasensor-for-ochratoxin-a-detection-using-polythiophene-3-carboxylic-acid
#17
H Zejli, K Yugender Goud, Jean Louis Marty
This work demonstrates the development of electrochemical aptasensor using ochratoxin A (OTA) aptamers. Different aptamer coupling strategies were tested using polythiophene-carboxylic acid (PT3C) and polypyrrole-3-carboxylic acid (PP3C). The best sensitivity was recorded by polythiophene-3-carboxylic acid (PT3C) on screen-printed carbon electrode (SPCE) to attain the direct detection of OTA. The quantification of OTA was achieved by using electrochemical impedance spectroscopy. A good dynamic range 0.125-2...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29759204/internal-standard-based-sers-aptasensor-for-ultrasensitive-quantitative-detection-of-ag-ion
#18
Yan Wu, Tingting Jiang, Zhaoyang Wu, Ruqin Yu
A ratiometric surface-enhanced Raman scattering (SERS) aptasensor based on internal standard (IS) methods was proposed for the ultrasensitive and reproducible quantitative detection of silver ion (Ag+ ) with Au@Ag core-shell nanoparticle (Au@Ag NP) substrate. In principle, the thiolated 5'-Rox C-containing labeled aptamer probe (Rox-aptamer) is firstly immobilized on the SERS substrate surface and then hybridizes with the complementary DNA (cDNA) to form a rigid double-stranded DNA (dsDNA), in which the Rox Raman labels is used to produce the Raman signal...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29759176/carbon-nanosphere-based-fluorescence-aptasensor-for-targeted-detection-of-breast-cancer-cell-mcf-7
#19
Dandan Yang, Mei Liu, Jing Xu, Chao Yang, Xiaoxiao Wang, Yongbing Lou, Nongyue He, Zhifei Wang
In this work, carbon nanosphere (CNS)-based fluorescence "turn off/on" aptasensor was developed for targeted detection of breast cancer cell MCF-7 by conjugation with FAM (a dye)-labeled mucin1 (MUC1) aptamer P0 (P0-FAM), which can recognize MUC1 protein overexpressed on the surface of MCF-7. Different from other carbon based fluorescence quenching materials, CNSs prepared by the carbonization of glucose not only have the high fluorescence quenching efficiency (98.8%), but also possess negligible cytotoxicity (in the concentration range of 0-1 mg/mL, which is 10 times higher than that of traditional carbon nanotubes or graphene oxide (0-100 µg/mL))...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29757205/label-free-g-quadruplex-aptamer-fluorescence-assay-for-ochratoxin-a-using-a-thioflavin-t-probe
#20
Kefeng Wu, Changbei Ma, Han Zhao, Hailun He, Hanchun Chen
Ochratoxin A (OTA) is one of the most common mycotoxins contaminating feed and foodstuffs. Therefore, a great deal of concern is associated with AFB1 toxicity. In this work, a fast and sensitive fluorescence aptamer biosensor has been proposed for the OTA assay. In the absence of OTA, the OTA aptamer can form a G-quadruplex structure with thioflavin T (ThT) dye, which results in increased fluorescence. After joining OTA, OTA aptamer combines with OTA and the G-quadruplex can be formed. Only faint fluorescence was finally observed when ThT weakly reacts with the quadruplex...
May 12, 2018: Toxins
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