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Jingguo Xu, Jia Guo, Sarah Wanjiku Mania, Yumeng Yang, Yimin Hu, Xuanxuan Li, Jiarong Qiu, Zhihong Xin
An ultra-sensitive aptamer-based biosensor for the detection of staphylococcus aureus was established by adopting the nicking enzyme amplification reaction (NEAR) and the rolling circle amplification (RCA) technologies. Aptamer-probe (AP), containing an aptamer and a probe sequence, was developed to act as the recognition unit of the biosensor, which was specifically bound to S. aureus. The probe was released from AP and initiated into the subsequent DNA amplification reactions where S. aureus was present, converting the detection of S...
March 15, 2018: Analytical Biochemistry
Hua Yu, Jing Han, Shangjie An, Gang Xie, Sanping Chen
Metal-organic frameworks (MOFs) as a new class of porous materials have attracted increasing attention in the field of biomimetic catalysis. This study firstly reports a mixed valence state Ce-MOF possessing intrinsic catalytic activity towards thionine (Thi), and its application in constructing an amplified electrochemical aptasensor for thrombin detection. As noticed, the novel catalytic process combines the advantages of 3D infinite extension of the Ce(III, IV)-MOF skeleton containing large amounts of catalytic sites and spontaneous recycling of the Ce(III)/Ce(IV) for electrochemical reduction of Thi, thereby presenting amplified electrochemical signals...
March 5, 2018: Biosensors & Bioelectronics
Li Wang, Aiguo Wu, Gang Wei
Graphene-based nanomaterials have been widely utilized to fabricate various biosensors for environmental monitoring, food safety, and biomedical diagnostics. The combination of aptamers with graphene for creating biofunctional nanocomposites improved the sensitivity and selectivity of fabricated biosensors due to the unique molecular recognition and biocompatibility of aptamers. In this review, we highlight recent advances in the design, fabrication, and biomedical sensing application of graphene-based aptasensors within the last five years (2013-current)...
March 12, 2018: Analyst
Rania Oueslati, Cheng Cheng, Jayne Wu, Jiangang Chen
Cocaine is one of the most used illegal recreational drugs. Developing an on-site test for cocaine use detection has been a focus of research effort, since it is essential to the control and legal action against drug abuse. Currently most of cocaine detection methods are time-consuming and require special or expensive equipment, and the detection often suffers from high cross-reactivity with cocaine metabolites and relative low sensitivity with the best limit of detection reported at sub nanomolar (nM) level...
February 27, 2018: Biosensors & Bioelectronics
Sai Wang, Yiyang Dong, Xingguo Liang
Although surface plasmon resonance (SPR) technique and aptamer technology shows great potential in analytical and biological chemistry, direct capture and analysis of small molecules using SPR remains tough. Detection sensitivity of aptasensor and recognition ability of aptamer is limited, because direct immobilization of aptamer causes large steric hindrance and strand entanglement. Herein, we chose a typical small molecule-tetracycline (Mw. 444.4 g/mol) as a model, and combined aptamer technology, DNA nanostructure, and commercial Biacore T200 SPR instrument to develop a straightforward format SPR aptasensor...
February 27, 2018: Biosensors & Bioelectronics
Chen Zhou, Haimin Zou, Chengjun Sun, Dongxia Ren, Wei Xiong, Yongxin Li
Based on a novel signal amplification strategy by catalytic hairpin assembly and displacement of G-quadruplex DNA, an enzyme-free, non-label fluorescent aptasensing approach was established for sensitive detection of four tetracycline veterinary drugs in milk. The network consisted of a pair of partially complementary DNA hairpins (HP1 and HP2). The DNA aptamer of four tetracycline veterinary drugs was located at the sticky end of the HP1. The ring region of HP1 rich in G and C could form a stable G-quadruplex structure, which could emit specific fluorescence signal after binding with the fluorescent dye and N-methylmesoporphyrin IX (NMM)...
March 8, 2018: Analytical and Bioanalytical Chemistry
Girma Selale Geleta, Zhen Zhao, Zhenxin Wang
In this study, we developed a novel reduced graphene oxide/molybdenum disulfide/polyaniline@gold nanoparticles-based electrochemical aptasensor (termed as RGO/MoS2 /PANI@AuNPs/Apt) for detection of aflatoxin B1 (AFB1 ). The RGO/MoS2 /PANI nanocomposites were synthesized and characterized by multiple techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). A glassy carbon electrode (GCE) was then modified by the RGO/MoS2 /PANI nanocomposites, coated with a chitosan (Cs) film, and followed by AuNPs attachment for immobilizing the AFB1 aptamers...
March 6, 2018: Analyst
Christy Hui, Meng Liu, Yingfu Li, John David Brennan
We report a paper-based aptasensor platform that uses two reaction zones and a connecting bridge along with printed multifunctional bio/nano materials to achieve molecular recognition and signal amplification. Upon addition of analyte to the first zone, a fluorescently labelled DNA or RNA aptamer is desorbed from printed graphene oxide, rapidly producing an initial fluorescence signal. The released aptamer then flows to the second zone where it reacts with printed reagents to initiate rolling circle amplification, generating DNA amplicons containing a peroxidase-mimicking DNAzyme, which produces a colorimetric readout that can be read in an equipment-free manner or with a smartphone...
March 5, 2018: Angewandte Chemie
Rui Yang, Shuwen Liu, Zhenjie Wu, Ying Tan, Shuqing Sun
In this work, we developed a robust and ultrasensitive bio-sensor based on the target-aptamer recognition strategy and microscopic enumeration of gold nanoparticles (AuNPs) using dark field microscopy (DFM). The aptasensor with a core-shell structure consisting of a magnetic bead (MB), aptamer and AuNPs was fabricated by complementary hybridization of the DNA probe on the AuNPs surface to the aptamer coupled to the MB. Upon addition of the target molecule, the strong interaction between the aptamer and the target molecule, thrombin, results in the release of the AuNPs from the MB...
May 15, 2018: Talanta
Atefeh Sarafan Sadeghi, Mohammad Mohsenzadeh, Khalil Abnous, Seyed Mohammad Taghdisi, Mohammad Ramezani
Specific ssDNA aptamers for the antibiotic florfenicol (FF) were developed from an enriched nucleotide library using magnetic beads-based SELEX (Systematic Evolution of Ligands by EXponential enrichment) technique with high-binding affinity. After 12 rounds of selection, thirty-six sequences were obtained that were then divided into five major families, according to the primary sequence similarity. Binding affinity analyses of three fluorescently tagged aptamers belonging to different families demonstrated that the dissociation constants (Kd ) were in the low nanomolar range (Kd = 52...
May 15, 2018: Talanta
Chengquan Wang, Jing Qian, Keqi An, Chanchan Ren, Xiaoting Lu, Nan Hao, Qian Liu, Henan Li, Xingyi Huang, Kun Wang
Aflatoxin B1 (AFB1), one of the most common mycotoxins in food matrixes, has been identified as the most toxic contaminant with mutagenic, teratogenic, immunosuppressive, and carcinogenic effects. In this work, a magnetically assembled aptasensing device has been designed for label-free determination of AFB1 by employing a disposable screen-printed carbon electrode (SPCE) covered with a designed polydimethylsiloxane (PDMS) film as the micro electrolytic cell. The magnetically controlled bio-probes were firstly prepared by immobilization of the thiolated aptamers on the Fe3 O4 @Au magnetic beads, which was rapidly assembled on the working electrode of SPCE within 10 s, by using a magnet placed at the opposite side...
February 28, 2018: Biosensors & Bioelectronics
Baoshan He, Gengan Du
In the current study, a sensitive electrochemical sensing strategy based on aptamer (APT) for detection of sulfadimidine (SM2 ) was developed. A bare gold electrode (AuE) was first modified with 2-aminoethanethiol (2-AET) through self-assembly, used as linker for the subsequent immobilization of multi-walled carbon nanotubes and gold nanoparticle composites (MWCNTs/AuNPs). Then, the thiolated APT was assembled onto the electrode via sulfur-gold affinity. When SM2 existed, the APT combined with SM2 and formed a complex structure...
March 3, 2018: Analytical and Bioanalytical Chemistry
Cheng Zhang, Xiaowen Dou, Lei Zhang, Meifeng Sun, Ming Zhao, Zhen OuYang, Dandan Kong, F Logrieco Antonio, Meihua Yang
Aflatoxin B₁ (AFB₁) is a very hazardous carcinogen, readily contaminating foodstuffs and traditional Chinese medicines (TCMs) that has inspired increasing health concerns due to dietary exposure. Colloidal nanocrystals have been proposed as optical labels for aptasensor assembly, but these typically require tedious multistep conjugation and suffer from unsatisfactory robustness when used for complex matrices. In the present study, we report a rapid and sensitive method for screening for trace AFB₁ levels in TCMs using a label-free fluorescent aptasensor PicoGreen dye-based strategy...
February 28, 2018: Toxins
Brian Kim, Kang Wook Chung, Ji Hoon Lee
A cost-effective and simple biosensor was developed for the accurate and rapid monitoring of norovirus GII in a sample. The modified DNA aptamer, 5 guanines linked to conventional DNA aptamer, designed for the research, was able to rapidly capture norovirus GII in tap water as well artificial urine. In addition, the extra guanines of the modified DNA aptamer enhanced the sensitivity of biosensor with guanine chemiluminescence detection based on the principle of intra chemiluminescent resonance transfer (Intra-CRET)...
February 11, 2018: Journal of Pharmaceutical and Biomedical Analysis
Guoneng Cai, Zhengzhong Yu, Rongrong Ren, Dianping Tang
A competitive-displacement reaction strategy based on target-induced dissociation of gold nanoparticles-coated graphene nanosheet (AuNPs/GN) from CdS quantum dots-functionalized mesoporous titanium dioxide (CdS QDs/TiO2) was designed for the sensitive photoelectrochemical (PEC) aptasensing of prostate-specific antigen (PSA) through the exciton-plasmon interaction (EPI) between CdS QDs and AuNPs. To construct such an aptasensing system, capture DNA was initially conjugated covalently onto CdS QDs/TiO2-modified electrode, and then AuNPs/GN-labeled PSA aptamer was bound onto biofunctionalized CdS QDs/TiO2 via hybridization chain reaction of partial bases with capture DNA...
February 21, 2018: ACS Sensors
Rajni Bala, Sherry Mittal, Rohit K Sharma, Nishima Wangoo
In the present study, we report a highly sensitive, rapid and low cost colorimetric monitoring of malathion (an organophosphate insecticide) employing a basic hexapeptide, malathion specific aptamer (oligonucleotide) and silver nanoparticles (AgNPs) as a nanoprobe. AgNPs are made to interact with the aptamer and peptide to give different optical responses depending upon the presence or absence of malathion. The nanoparticles remain yellow in color in the absence of malathion owing to the binding of aptamer with peptide which otherwise tends to aggregate the particles because of charge based interactions...
February 5, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Guiyin Li, Shanshan Li, Zhihong Wang, Yewei Xue, Chenyang Dong, Junxiang Zeng, Yong Huang, Jintao Liang, Zhide Zhou
Sensitive and accurate detection of tumor markers is critical to early diagnosis, point-of-care and portable medical supervision. Alpha fetoprotein (AFP) is an important clinical tumor marker for hepatocellular carcinoma (HCC), and the concentration of AFP in human serum is related to the stage of HCC. In this paper, a label-free electrochemical aptasensor for AFP detection was fabricated using AFP-aptamer as the recognition molecule and thionin/reduced graphene oxide/gold nanoparticles (TH/RGO/Au NPs) as the sensor platform...
February 13, 2018: Analytical Biochemistry
Shi Ting Lee, David Beaumont, Xiao Di Su, Kasturi Muthoosamy, Siu Yee New
Single strand DNA (ssDNA) chimeras consisting of a silver nanoclusters-nucleating sequence (NC) and an aptamer are widely employed to synthesize functional silver nanoclusters (AgNCs) for sensing purpose. Despite its simplicity, this chimeric-templated AgNCs often leads to undesirable turn-off effect, which may suffer from false positive signals caused by interference. In our effort to elucidate how the relative position of NC and aptamer affects the fluorescence behavior and sensing performance, we systematically formulated these NC and aptamer regions at different position in a DNA chimera...
June 20, 2018: Analytica Chimica Acta
Mahboube Naderi, Morteza Hosseini, Mohammad Reza Ganjali
In this work, we studied the feasibility of interaction among gold nanoparticles (AuNPs) and a cationic dye in an aptasensor system for the detection of potassium ions. The presence and absence of potassium in the solution was distinguishable by different colors (between orange and green) appeared after reaction. Cationic dye (Y5GL) acts as a new aggregator for AuNP-based sensors which changes the aggregated AuNP solution color from blue-purple to green. In the presence of K+ ions, the aptamer dissociated from the surface of the AuNP so that free AuNPs and cationic dye make the solution green...
February 1, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Qingzhi Han, Rongyu Wang, Bin Xing, Huitong Chi, Dan Wu, Qin Wei
A novel photoelectrochemical (PEC) aptasensor based on cerium (Ce) doped CdS modified graphene (G)/BiYWO6 was designed, which exhibits enhanced PEC intensity compared with pure BiYWO6, G/BiYWO3 and BiYWO6/Ce:CdS. In this scenario, ascorbic acid (AA) was exploited as an efficient and non-poisonous electron donor for scavenging photogenerated holes. The doping of Ce in CdS promoted its visible light absorption range and facilitated the charge transfer rate as well as hindered the h+/e- recombination. Moreover, the combination of G further promoted the electron carrier separation and transfer process due to its excellent electron collection and shuttling characteristic...
January 26, 2018: Biosensors & Bioelectronics
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