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Aptamers

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https://www.readbyqxmd.com/read/28930315/mapping-the-interaction-sites-of-mucin-1-and-dna-aptamer-by-atomic-force-microscopy
#1
Nan Wang, Miaomiao Zhang, Xuejuan Chen, Xingxing Ma, Chen Li, Zhe Zhang, Jilin Tang
Mucin 1 (MUC1) is an attractive tumor marker for cancer diagnosis. An advanced atomic force microscopy (AFM) mode, peak-force tapping AFM with an aptamer functionalized tip, was introduced to map the specific interaction sites of an aptamer and MUC1. Single molecular force spectroscopy (SMFS) was used to investigate dynamic parameters of the aptamer-MUC1.
September 20, 2017: Analyst
https://www.readbyqxmd.com/read/28929744/optimizing-stem-length-to-improve-ligand-selectivity-in-a-structure-switching-cocaine-binding-aptamer
#2
Miguel A D Neves, Aron A Shoara, Oren Reinstein, Okty Abbasi Borhani, Taylor R Martin, Philip E Johnson
Understanding how aptamer structure and function are related is crucial in the design and development of aptamer-based biosensors. We have analysed a series of cocaine-binding aptamers with different lengths of their stem 1 in order to understand the role that this stem plays in the ligand-induced structure-switching binding mechanism utilized in many of the sensor applications of this aptamer. In the cocaine-binding aptamer the length of stem 1 controls whether the structure-switching binding mechanism for this aptamer occurs or not...
September 20, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28929743/the-design-of-a-dual-channel-self-reference-photoelectrochemical-biosensor
#3
Nan Hao, Ying Zhang, Hui Zhong, Zhou Zhou, Rong Hua, Jing Qian, Qian Liu, Henan Li, Kun Wang
Photoelectrochemical (PEC) biosensors are usually based on the single photocurrent change caused by biorecognition events between analytes and probes. However, the photocurrent may be influenced by other factors besides target analytes and bring a false result. To improve the accuracy and reliability of PEC detection, here we proposed the design of a dual channel self-reference PEC biosensors. CdTe and CdTe-graphene oxide (GO) were chosen as the two PEC active material and modified onto two adjacent areas on the ITO electrode...
September 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28929739/ultrasensitive-capture-detection-and-release-of-circulating-tumor-cells-using-nanochannel-ionchannel-hybrid-coupled-with-electrochemical-detection-technique
#4
Jing Cao, Xiao-Ping Zhao, Muhammad Rizwan Younis, Zhong-Qiu Li, Xing-Hua Xia, Chen Wang
With the growing demands of the early, accurate, and sensitive diagnosis for cancers, the development of new diagnostic technologies becomes increasingly important. In this study, we proposed a strategy for efficient capture and sensitive detection of circulating tumor cells (CTCs) using array nanochannel-ionchannel hybrid coupled with electrochemical detection technique. The aptamer probe was immobilized on the ionchannel surface to couple with the protein overexpressed on CTCs membrane. Through this special molecular recognition, CTCs can be selectively captured...
September 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28929152/size-dependent-targeted-delivery-of-gold-nanoparticles-modified-with-the-il-6r-specific-aptamer-air-3a-to-il-6r-carrying-cells
#5
Lisa Prisner, Nadine Bohn, Ulrich Hahn, Alf Mews
The delivery of gold nanoparticles (AuNPs) to specific cells strongly depends on the properties e.g. the size of the particles and is of great interest for a large variety of biomedical applications. Here we investigated the size dependence of the receptor-ligand mediated AuNP delivery to cells by comparing very small "molecular" Au-clusters of only 2 nm to larger 7 nm and 36 nm AuNPs with a distinct surface plasmon resonance. Since the molecular weight in this range changes by almost three orders of magnitude, we show how the amount of gold relates to the number of delivered AuNPs...
September 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28928437/as1411-aptamer-anionic-linear-globular-dendrimer-g2-iohexol-selective-nano-theranostics
#6
Pardis Mohammadzadeh, Reza Ahangari Cohan, Seyedeh Masoumeh Ghoreishi, Ahmad Bitarafan-Rajabi, Mehdi Shafiee Ardestani
Molecular theranostics is of the utmost interest for diagnosis as well as treatment of different malignancies. In the present study, anionic linear globular dendrimer G2 is employed as a suitable carrier for delivery and AS1411 aptamer is exploited as the targeting agent to carry Iohexol specifically to the human breast cancer cells (MCF-7). Dendrimer G2 was prepared and conjugation of dendrimer and aptamer was carried out thereafter. Based on the data yielded by AFM, morphology of smooth and spherical non-targeted dendrimer changed to the rough aspherical shape when it conjugated...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28925689/highly-efficient-capture-and-electrochemical-release-of-circulating-tumor-cells-by-using-aptamers-modified-gold-nanowire-arrays
#7
Ting-Ting Zhai, Dekai Ye, Qian-Wen Zhang, Zeng-Qiang Wu, Xing-Hua Xia
The effectively capturing and releasing of circulating tumor cells (CTCs) is of significant importance in cancer prognose and treatment. Herein, we report a highly efficient method to capture and release human leukemic lymphoblasts (CCRF-CEM) using aptamers modified gold nanowire arrays (AuNWs). The gold nanowires, showing tunable morphologies from relatively random pillar deposit to uniform arrays, were fabricated by electrochemical deposition using anodic aluminum oxide (AAO) as template. Upon simply modification with aptamers by Au-S chemistry, the uniform AuNWs exhibit higher specificity to target cells...
September 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28924154/a-dna-aptamer-efficiently-inhibits-the-infectivity-of-bovine-herpesvirus-1-by-blocking-viral-entry
#8
Jian Xu, Xixi Zhang, Shuanghai Zhou, Junjun Shen, Dawei Yang, Jing Wu, Xiaoyang Li, Meiling Li, Xiufen Huang, Joshua E Sealy, Munir Iqbal, Yongqing Li
Bovine herpesvirus 1 (BoHV-1) is an important pathogen of domestic and wild cattle responsible for major economic losses in dairy and beef industries throughout the world. Inhibition of viral entry plays a crucial role in the control of BoHV-1 infection and aptamers have been reported to inhibit viral replication. In this study, nine DNA aptamers that target BoHV-1 were generated using systemic evolution of ligands by exponential enrichment. Of the nine candidates, aptamer IBRV-A4 exhibited the highest affinity and specificity for BoHV-1, which bound to BoHV-1 with a Kd value of 3...
September 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28921494/solid-phase-synthesis-of-rna-analogs-containing-phosphorodithioate-linkages
#9
Xianbin Yang
The oligoribonucleotide phosphorodithioate (PS2-RNA) modification uses two sulfur atoms to replace two non-bridging oxygen atoms at an internucleotide phosphorodiester backbone linkage. Like a natural phosphodiester RNA backbone linkage, a PS2-modified backbone linkage is achiral at phosphorus. PS2-RNAs are highly stable to nucleases and several in vitro assays have demonstrated their biological activity. For example, PS2-RNAs silenced mRNA in vitro and bound to protein targets in the form of PS2-aptamers (thioaptamers)...
September 18, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/28918528/signaling-of-the-complement-cleavage-product-anaphylatoxin-c5a-through-c5ar-cd88-contributes-to-pharmacological-hematopoietic-stem-cell-mobilization
#10
Kamila Bujko, Sylwia Rzeszotek, Kai Hoehlig, Jun Yan, Axel Vater, Mariusz Z Ratajczak
Several mechanisms have been postulated for orchestrating the mobilization of hematopoietic stem/progenitor cells (HSPCs), and we previously proposed that activation of the complement cascade plays a crucial role in the initiation and execution of the egress of HSPCs from bone marrow (BM) into peripheral blood (PB). In support of this notion, we demonstrated that mice deficient in the mannan-binding lectin (MBL) pathway, which activates the proximal part of the complement cascade, as well as mice deficient in the fifth component of the complement cascade (C5), which is part of the distal part of the complement cascade, are poor mobilizers...
September 16, 2017: Stem Cell Reviews
https://www.readbyqxmd.com/read/28918052/a-ctla-4-antagonizing-dna-aptamer-with-antitumor-effect
#11
Bo-Tsang Huang, Wei-Yun Lai, Yi-Chung Chang, Jen-Wei Wang, Shauh-Der Yeh, Emily Pei-Ying Lin, Pan-Chyr Yang
The successful translation of cytotoxic T lymphocyte antigen-4 (CTLA-4) blockade has revolutionized the concept of cancer immunotherapy. Although monoclonal antibody therapeutics remain the mainstream in clinical practice, aptamers are synthetic oligonucleotides that encompass antibody-mimicking functions. Here, we report a novel high-affinity CTLA-4-antagonizing DNA aptamer (dissociation constant, 11.84 nM), aptCTLA-4, which was identified by cell-based SELEX and high-throughput sequencing. aptCTLA-4 is relatively stable in serum, promotes lymphocyte proliferation, and inhibits tumor growth in cell and animal models...
September 15, 2017: Molecular Therapy. Nucleic Acids
https://www.readbyqxmd.com/read/28918021/in%C3%A2-vitro-selection-of-cell-internalizing-dna-aptamers-in-a-model-system-of-inflammatory-kidney-disease
#12
Glory Ranches, Melanie Lukasser, Herbert Schramek, Andreas Ploner, Taras Stasyk, Gert Mayer, Günter Mayer, Alexander Hüttenhofer
Chronic kidney disease (CKD) is a progressive pathological condition marked by a gradual loss of kidney function. Treatment of CKD is most effective when diagnosed at an early stage and patients are still asymptomatic. However, current diagnostic biomarkers (e.g., serum creatinine and urine albumin) are insufficient for prediction of the pathogenesis of the disease. To address this need, we applied a cell-SELEX (systematic evolution of ligands by exponential enrichment) approach and identified a series of DNA aptamers, which exhibit high affinity and selectivity for cytokine-stimulated cells, resembling some aspects of a CKD phenotype...
September 15, 2017: Molecular Therapy. Nucleic Acids
https://www.readbyqxmd.com/read/28918019/dual-tumor-targeting-nanocarrier-system-for-sirna-delivery-based-on-prna-and-modified-chitosan
#13
Lin Li, Xiaoqin Hu, Min Zhang, Siyu Ma, Fanglin Yu, Shiqing Zhao, Nan Liu, Zhiyuan Wang, Yu Wang, Hua Guan, Xiujie Pan, Yue Gao, Yue Zhang, Yan Liu, Yang Yang, Xuemei Tang, Mingyuan Li, Cheng Liu, Zhiping Li, Xingguo Mei
Highly specific and efficient delivery of siRNA is still unsatisfactory. Herein, a dual tumor-targeting siRNA delivery system combining pRNA dimers with chitosan nanoparticles (CNPPs) was designed to improve the specificity and efficiency of siRNA delivery. In this dual delivery system, folate-conjugated and PEGylated chitosan nanoparticles encapsulating pRNA dimers were used as the first class of delivery system and would selectively deliver intact pRNA dimers near or into target cells. pRNA dimers simultaneously carrying siRNA and targeting aptamer, the second class of delivery system, would specifically deliver siRNA into the target cells via aptamer-mediated endocytosis or proper particle size...
September 15, 2017: Molecular Therapy. Nucleic Acids
https://www.readbyqxmd.com/read/28917799/a-reagentless-and-reusable-electrochemical-aptamer-based-sensor-for-rapid-detection-of-ampicillin-in-complex-samples
#14
Zhi-Gang Yu, Rebecca Y Lai
We report the design and fabrication of a "signal-on" electrochemical aptamer-based (E-AB) sensor for detection of ampicillin. The signaling of the sensor is based on target binding-induced changes in the conformation and flexibility of the methylene blue-modified aptamer probe. The sensor's response is fast; signal saturation can be reached in ~ 200s. Since all the sensor components are surface-immobilized, it is regenerable and can be reused for at least three times. It has demonstrated good specificity and is capable of differentiating between ampicillin and structurally similar antibiotics such as amoxicillin...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28917776/apta-nanosensors-for-detection-and-quantitative-determination-of-acetamiprid-a-pesticide-residue-in-food-and-environment
#15
REVIEW
Asma Verdian
In an effort to achieve high sensitive and selective detection of pesticide residues, numerous nanomaterial-based aptasensors are currently being developed for acetamiprid analysis. Recently, aptamers as a potent alternative of antibodies are used in biosensing platforms. There is tremendous interest in utilizing of nanomaterial as basic building blocks and signaling elements in aptasensors. The nanomaterials have the unique optical and electrical properties. The combination of nanomaterial and aptamer technology has opened a new window in pesticide residues monitoring...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28917759/detection-of-aflatoxin-b1-in-food-samples-based-on-target-responsive-aptamer-cross-linked-hydrogel-using-a-handheld-ph-meter-as-readout
#16
Mengmeng Zhao, Peilong Wang, Yajuan Guo, Lixu Wang, Fang Luo, Bin Qiu, Longhua Guo, Xiaoou Su, Zhenyu Lin, Guonan Chen
Aflatoxin B1 (AFB1) can cause great threat to human health, so the development of convenient and portable device for sensitive detection of AFB1 is highly desired. The portable pH meter has the characters of facile operation, low cost, and easy availability. Therefore, in this study, we investigate the applicability of utilizing a pH meter as the readout to develop a portable sensor for AFB1. The specific detection of AFB1 is realized via the combination of AFB1-responsive aptamer-cross-linked hydrogel. Upon the addition of AFB1, AFB1 binds to its aptamer with high affinity in lieu of aptamer/DNA complex, causing the collapse of hydrogel network and results in the releasing of urease into the solution...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28917752/facilely-self-assembled-magnetic-nanoparticles-aptamer-carbon-dots-nanocomposites-for-highly-sensitive-up-conversion-fluorescence-turn-on-detection-of-tetrodotoxin
#17
Hui Jin, Rijun Gui, Jie Sun, Yanfeng Wang
In this work, magnetic Fe3O4 nanoparticles (NPs) were modified with aptamer of tetrodotoxin (TTX) to form Fe3O4/aptamer complex. The self-assembling of carbon dots (CDs) and the aptamer generated Fe3O4/aptamer/CDs nanocomposites. The nanocomposites exhibited down-conversion fluorescence and up-conversion fluorescence (UCF) emissions simultaneously. When excited at a wavelength of 780nm, the UCF (peaked at 475nm) of nanocomposites increased regularly with the increase of TTX concentration [TTX]. In the [TTX] range from 0...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28917743/selection-of-an-aptamer-against-muscovy-duck-parvovirus-for-highly-sensitive-rapid-visual-detection-by-label-free-aptasensor
#18
Taofeng Lu, Qin Ma, Wenzhuo Yan, Yuanzhi Wang, Yuanyuan Zhang, Lili Zhao, Hongyan Chen
Muscovy duck parvovirus (MDPV) causes high mortality and morbidity in ducks. This study investigated a novel aptamer-based, label-free aptasensor detection of MDPV. In this study, we developed an ssDNA aptamer using the filtration partition and lambda exonuclease method with an affinity-based monitor and counter-screening process. After 15 rounds of SELEX (systematic evolution of ligands by exponential enrichment), the ssDNA aptamer Apt-10, which specifically bound to MDPV with high affinity (Kd = 467nM) was successfully screened, and the aptamer was also found to be good specific to MDPV...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28916151/dna-aptamer-generation-by-exselex-using-genetic-alphabet-expansion-with-a-mini-hairpin-dna-stabilization-method
#19
REVIEW
Ichiro Hirao, Michiko Kimoto, Kyung Hyun Lee
A novel aptamer generation method to greatly augment the affinity and stability of DNA aptamers was developed by genetic alphabet expansion combined with mini-hairpin DNA technology. The genetic alphabet expansion increases the physicochemical and structural diversities of DNA aptamers by introducing extra components, unnatural bases, as a fifth base, allowing for the enhancement of DNA aptamer affinities. Furthermore, the mini-hairpin DNA technology stabilizes DNA aptamers against nuclease digestion and thermal denaturation, by introducing an extraordinarily stable mini-hairpin DNA containing a GCGAAGC sequence...
September 12, 2017: Biochimie
https://www.readbyqxmd.com/read/28916037/electrochemical-aptasensor-for-human-osteopontin-detection-using-a-dna-aptamer-selected-by-selex
#20
Sofia G Meirinho, Luís G Dias, António M Peres, Lígia R Rodrigues
A DNA aptamer with affinity and specificity for human osteopontin (OPN), a potential breast cancer biomarker, was selected using the SELEX process, considering its homology rate and the stability of its secondary structures. This aptamer exhibited a satisfactory affinity towards OPN, showing dissociation constants lower than 2.5 nM. It was further used to develop a simple, label-free electrochemical aptasensor against OPN. The aptasensor showed good sensitivity towards OPN in standard solutions, being the square wave voltammetry (SWV), compared to the cyclic voltammetry, the most sensitive technique with detection and quantification limits of 1...
September 22, 2017: Analytica Chimica Acta
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