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J Yang, J Zhu, R Pei, J A Oliver, D W Landry, M N Stojanovic, Q Lin
We present a microfluidic aptamer-based biosensor for detection of low-molecular-weight biomarkers in patient samples. Using a microfluidic device that integrates aptamer-based specific analyte extraction, isocratic elution, and detection by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, we demonstrate rapid, sensitive and label-free detection of arginine vasopressin (AVP) in human plasma ultrafiltrate. AVP molecules in complex matrices are specifically captured by an aptamer that is immobilized on microbeads via affinity binding in a microchamber...
July 14, 2016: Analytical Methods: Advancing Methods and Applications
Van-Thuan Nguyen, Young Seop Kwon, Man Bock Gu
Aptasensors are promising biosensors, which take advantage of using aptamers as a recognition element. The combination of the excellent characteristics of aptamers and the leading detection platform techniques, such as optical, electrochemical with nanomaterial-integrated, or mass-sensitive techniques with high sensitivity and specificity draws a promising view for the application of the aptasensors for the detection of harmful small toxic chemicals and real-time monitoring in the environments. In spite of attraction of aptasensors, application of them is limited to the complex environment due to the facts that how the immobilization of aptamers onto the surface affects the functions of aptamers and their structures for the detection of environmental contaminants are not clearly known...
January 11, 2017: Current Opinion in Biotechnology
Na-Reum Ha, In-Pil Jung, Im-Joung La, Ho-Sup Jung, Moon-Young Yoon
Overuse of antibiotics has caused serious problems, such as appearance of super bacteria, whose accumulation in the human body through the food chain is a concern. Kanamycin is a common antibiotic used to treat diverse infections; however, residual kanamycin can cause many side effects in humans. Thus, development of an ultra-sensitive, precise, and simple detection system for residual kanamycin in food products is urgently needed for food safety. In this study, we identified kanamycin-binding aptamers via a new screening method, and truncated variants were analyzed for optimization of the minimal sequence required for target binding...
January 5, 2017: Scientific Reports
Eleonora Alfinito, Lino Reggiani, Rosella Cataldo, Giorgio De Nunzio, Livia Giotta, Maria Rachele Guascito
Aptamers are chemically produced oligonucleotides, able to bind a variety of targets such as drugs, proteins and pathogens with high sensitivity and selectivity. Therefore, aptamers are largely employed for producing label-free biosensors (aptasensors), with significant applications in diagnostics and drug delivery. In particular, the anti-thrombin aptamers are biomolecules of high interest for clinical use, because of their ability to recognize and bind the thrombin enzyme. Among them, the DNA 15-mer aptamer (TBA), has been widely explored around the possibility of using it in aptasensors...
January 4, 2017: Nanotechnology
Haisheng Liu, Changbei Ma, Feng Ning, Hanchun Chen, Hailun He, Kemin Wang, Jun Wang
The present work demonstrates a simple, rapid and label-free ATP detection method using a fluorescent aptasensor that is based on G-quadruplex formation. In the absence of ATP, the Thioflavin T (ThT) dye binds to the G-rich ATP aptamer and forms an ATP aptamer/ThT G-quadruplex complex, which results in high fluorescence intensity. Upon addition of ATP, the ATP aptamer/ThT complex will be replaced by the formation of an ATP aptamer/ATP complex. During this process, separation of the ThT dye from the ATP aptamer/ThT complex decreases the fluorescence intensity of the reaction mixture dramatically...
December 21, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Esmaeil Heydari-Bafrooei, Nazgol Sadat Shamszadeh
A densely packed gold nanoparticles on the rGO-MWCNT platform was used as the basis for an ultrasensitive label-free electrochemical aptasensor to detect the biomarker prostate specific antigen (PSA) in serum. The detection was based on that the variation of electron transfer resistance (Rct) and differential pulse voltammetry (DPV) current were relevant to the formation of PSA-aptamer complex at the modified electrode surface. Compared with pure AuNPs, rGO-MWCNT and MWCNT/AuNPs, the rGO-MWCNT/AuNPs nanocomposite modified electrode was the most sensitive aptasensing platform for the determination of PSA...
December 22, 2016: Biosensors & Bioelectronics
Amina Rhouati, Gaelle Catanante, Gilvanda Nunes, Akhtar Hayat, Jean-Louis Marty
Various methodologies have been reported in the literature for the qualitative and quantitative monitoring of mycotoxins in food and feed samples. Based on their enhanced specificity, selectivity and versatility, bio-affinity assays have inspired many researchers to develop sensors by exploring bio-recognition phenomena. However, a significant problem in the fabrication of these devices is that most of the biomolecules do not generate an easily measurable signal upon binding to the target analytes, and signal-generating labels are required to perform the measurements...
December 18, 2016: Sensors
Seyyed Mehdi Khoshfetrat, Masoud A Mehrgardi
The increasing demands for early, accurate and ultrasensitive diagnosis of cancers demonstrate the importance of the development of new amplification strategies or diagnostic technologies. In the present study, an aptamer-based electrochemical biosensor for ultrasensitive and selective detection of leukemia cancer cells has been introduced. The thiolated sgc8c aptamer was immobilized on gold nanoparticles-coated magnetic Fe3O4 nanoparticles (Apt-GMNPs). Ethidium bromide (EB), intercalated into the stem of the aptamer hairpin, provides the read-out signal for the quantification of the leukemia cancer cells...
December 12, 2016: Bioelectrochemistry
Kunyi Xiao, Juan Liu, Hui Chen, Song Zhang, Jilie Kong
A label-free and high-efficient graphene oxide (GO)-based aptasensor was developed for the detection of low quantity cancer cells based on cell-triggered cyclic enzymatic signal amplification (CTCESA). In the absence of target cells, hairpin aptamer probes (HAPs) and dye-labeled linker DNAs stably coexisted in solution, and the fluorescence was quenched by the GO-based FÖrster resonance energy transfer (FRET) process. In the presence of target cells, the specific binding of HAPs with the target cells triggered a conformational alternation, which resulted in linker DNA complementary pairing and cleavage by nicking endonuclease-strand scission cycles...
November 25, 2016: Biosensors & Bioelectronics
Meng-Qi He, Kun Wang, Jin Wang, Yong-Liang Yu, Rong-Huan He
To specifically and sensitively identify bisphenol A (BPA) with a simple and rapid method is very important for food safety. Using an anti-BPA aptamer and Mo2C nanotubes, we developed a label-free and low-background signal biosensor for BPA detection. The anti-BPA aptamer drastically increased the fluorescence signal of N-methylmesoporphyrin IX under an assistance of Help-DNA. Additionally, BPA can interact with the anti-BPA aptamer and switch its conformation to prevent the formation of a G-quadruplex, resulting in fluorescence quenching...
December 15, 2016: Analytical and Bioanalytical Chemistry
Lijun Wang, Ronghui Wang, Fang Chen, Tieshan Jiang, Hong Wang, Michael Slavik, Hua Wei, Yanbin Li
In this study, quartz crystal microbalance (QCM) was used to select aptamers against Salmonella typhimurium. To increase the success rate of Systematic Evolution of Ligands Exponential Enrichment (SELEX), the affinity of DNA pool in each round was simultaneously tracked using QCM in order to avoid the loss of high-quality aptamers. When the frequency change reached a maximum value after several rounds of selection and counter-selection, the candidate pool was cloned and sequenced. Out of three aptamer candidates, aptamer B5 showed high specificity and binding affinity with dissociation constant (Kd value) of 58...
April 15, 2017: Food Chemistry
Jing Shen, Hongyang Wang, Chunxiang Li, Yanyan Zhao, Xijuan Yu, Xiliang Luo
In this work, a simple and highly sensitive label-free electrochemical aptasensor for adenosine detection was developed based on target-aptamer binding triggered nicking endonuclease-assisted strand-replacement DNA polymerization and rolling circle amplification (RCA) strategy. The magnetic beads (MB) probe, which was attached the aptamer of adenosine and mDNA, was firstly fabricated. In the presence of adenosine, mDNA was released from MB upon recognition of the aptamer to target adenosine. The released mDNA as the primer activated autonomous DNA polymerization/nicking process and accompanied by the continuous release of replicated DNA fragments...
April 15, 2017: Biosensors & Bioelectronics
Jiali Liu, Min Zhao, Ying Zhuo, Yaqin Chai, Ruo Yuan
The intermolecular electrochemiluminescence resonance energy transfer (ECL-RET) between luminol and Ru(bpy)32+ was studied extensively to achieve the sensitive bio-analysis owing to the perfect spectral overlap of the donor and acceptor, but it still suffers from the challenging issue of low energy transfer efficiency. Here, the intramolecular ECL-RET towards the novel ECL compound containing the donor of luminol and the acceptor of Ru(bpy)2(mcbpy)2+ was designed and investigated for the first time (The compound was abbreviated as Lum-Ru)...
December 8, 2016: Chemistry: a European Journal
Zahra Shekari, Hamid R Zare, Ali Falahati
The present study aims at the fabrication of a novel electrochemical aptasensor, Ap-GA-AMSN-GCE, for the label-free determination of hemin and hemoglobin (Hb). Basically, the electrochemical reduction current of hemin or Hb incubated on Ap-GA-AMSN-GCE in the presence of oxygen serves as an excellent signal for quantitative determination of these analytes. By differential pulse voltammetry, the calibration plot was linear in the concentration range of 1.0 × 10(-19)-1.0 × 10(-6) M of hemin and Hb. Also, the detection limits, DL, of hemin and Hb were found to be 7...
February 1, 2017: Analytical Biochemistry
Jiajia Lv, Sen Zhao, Shijia Wu, Zhouping Wang
Water safety is one of the most pervasive problems afflicting people throughout the world. Microcystin-LR (MC-LR), a representative toxin released by cyanobacteria, poses an increasing and serious threat to water safety. In order to develop facile, specific and sensitive detection methods for MC-LR, we fabricated an ultrasensitive fluorescence aptasensor using the enhanced fluorescence of UCNP and the effective quenching ability, high affinity toward single strand DNA (ssDNA) of MoS2 (termed as FAUM). This assay specifically determined MC-LR in the linear range of 0...
April 15, 2017: Biosensors & Bioelectronics
Aixue Li, Jian Zhang, Jichuan Qiu, Zhenhuan Zhao, Cheng Wang, Chunjiang Zhao, Hong Liu
It has been reported that tungsten disulfide (WS2) can bind single-stranded DNA (ssDNA) with high affinity while it has less affinity toward double stranded DNA (dsDNA). In this work, for the first time, the high affinity between WS2 and ssDNA was used to construct stable sensing interface for ATP detection. A DNA sequence with -SH at one end was first immobilized on Au electrode. WS2 nanosheets were immobilized on the SH-DNA/Au electrode surface due to the strong affinity between WS2 and ssDNA. Then the WS2 nanosheets were used to immobilize ATP binding aptamer (ABA) through the high affinity between WS2 and ssDNA, too...
January 15, 2017: Talanta
Tianhong Lou, Hong Qiang, Zhengbo Chen
A growing body of evidence indicates that lysozyme plays a significant role as an indicator for many diseases and a drug for treatment of infections, ulcers and to study the spatial conformation, enzyme kinetics, and molecular immunology. Therefore, highly sensitive determination of lysozyme is necessary and vital in a wide variety of fields. In this work, we put forward a simple but effective strategy for colorimetric visualization of lysozyme based on iodide-responsive Cu@Au nanoparticles (Cu@Au NPs) as well as the iodide-catalyzed H2O2-TMB (3,3,5,5-tetramethylbenzidine) reaction system...
January 15, 2017: Talanta
Harriet Khang, Kelly Cho, Stephanie Chong, Ji Hoon Lee
Using a dual DNA aptamer (CEA aptamer linked to hemin aptamer), capable of rapidly capturing carcinoembryonic antigen (CEA) and hemin, an all-in-one dual-aptasensor with 1,1'-oxalyldiimidazole (ODI) chemiluminescence detection was developed for the early diagnosis of human cancer. CEA and hemin competitively bound with the dual DNA aptamer while the mixture in a detection cell was incubated for 30min at room temperature. When Amplex Red and H2O2 were added in the detection cell after the incubation, the yield of resorufin formed from the reaction Amplex Red and H2O2 depended on the concentration of HRP-mimicking G-quardruplex DNAzyme formed from the binding interaction between hemin and the dual DNA aptamer...
April 15, 2017: Biosensors & Bioelectronics
Zhihong Zhang, Chuanpan Guo, Shuai Zhang, Linghao He, Minghua Wang, Donglai Peng, Junfeng Tian, Shaoming Fang
We synthesized two kinds of carbon-based nanocomposites of silver nanoclusters (AgNCs). An aptamer for targeted platelet-derived growth factor-BB (PDGF-BB) detection was used as the organic phase to produce AgNCs@Apt, three dimensional reduced graphene oxide@AgNCs@Aptamer (3D-rGO@AgNCs@Apt), and graphene quantum dots@AgNCs@Aptamer (GQD@AgNCs@Apt) nanocomposites. The formation mechanism of the developed nanocomposites was described by detailed characterizations of their chemical and crystal structures. Subsequently, the as-synthesized nanoclusters containing aptamer strands were applied as the sensitive layers to fabricate a novel electrochemical aptasensor for the detection of PDGF-BB, which may be directly used to determine the target protein...
March 15, 2017: Biosensors & Bioelectronics
Lanlan Wang, Rongna Ma, Liushan Jiang, Liping Jia, Wenli Jia, Huaisheng Wang
A novel dual-signal ratiometric electrochemical aptasensor for highly sensitive and selective detection of thrombin has been designed on the basis of signal-on and signal-off strategy. Ferrocene labeled hairpin probe (Fc-HP), thrombin aptamer and methyl blue labeled bio-bar-coded AuNPs (MB-P3-AuNPs) were rationally introduced for the construction of the assay platform, which combined the advantages of the recognition of aptamer, the amplification of bio-bar-coded nanoprobe, and the ratiometric signaling readout...
November 1, 2016: Biosensors & Bioelectronics
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