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paper based assay

Yubin Li, Sheng Liu, Qiujuan Deng, Liansheng Ling
A sensitive colorimetric DNA biosensor for specific detection of single stranded oligonucleotide (ssDNA) is proposed in this paper. The biosensor is based on silver-coated glass (SCGS) and G-quadruplex-hemin DNAzyme. Capture DNA is immobilized on the surface of SCGS by Ag-S bond. Signal DNA can be used to hybridize with the target DNA which is selected from the Hepatitis B virus(HBV) gene as target HBV DNA, and the HRP-mimicking G-quadruplex-hemin DNAzyme can be formed through the function of a guanine-rich fragment from signal DNA to catalyze the oxidation of 2,2-azinobis(3-ethylbenzothiozoline)-6-sulfonicacid (ABTS(2-) ) by H2 O2 ...
November 16, 2017: Journal of Medical Virology
Ana Lozano, Samanta Uclés, Ana Uclés, Carmen Ferrer, Amadeo R Fernández-Alba
This paper presents an efficiency evaluation of GC coupled with quadrupole Orbitrap MS for identification andquantitation in the multiresidue pesticide analysis of baby foods in full-scan mode. The identification criteria were studied following SANTE guidelines (retention time, mass accuracy, and ion ratio), comfortably complying with the values established, even at 0.003 mg/kg. Method validation was carried out on 15 selected GC-amenable pesticides covered by Commission Directive No. 2006/125/EC in three different baby food matrixes...
November 15, 2017: Journal of AOAC International
Gopakumar Kamalakshakurup, Abraham P Lee
Single cell analysis has emerged as a paradigm shift in cell biology to understand the heterogeneity of individual cells in a clone for pathological interrogation. Microfluidic droplet technology is a compelling platform to perform single cell analysis by encapsulating single cells inside picoliter-nanoliter (pL-nL) volume droplets. However, one of the primary challenges for droplet based single cell assays is single cell encapsulation in droplets, currently achieved either randomly, dictated by Poisson statistics, or by hydrodynamic techniques...
November 15, 2017: Lab on a Chip
Carl-Olof Hillerdal, Rita Ötvös, Tünde Szatmári, Sulaf Abd Own, Gunnar Hillerdal, Åsa-Lena Dackland, Katalin Dobra, Anders Hjerpe
The effect of chemotherapy may be improved by combining the most effective drugs based on testing the sensitivity of the individual tumor ex vivo. Such estimations of tumor cells from effusions have so far not been implemented in the clinical routine as a basis for individualized choice of therapy. One obstacle for such analyses is the admixture of benign cells that might obscure the results. In this paper we test and compare two ways of performing the analysis specifically on tumor cells. First we enrich the tumor cells, using antibody labeled magnetic separation, and measure the effects of subsequent drug exposure with the metabolic activity assays WST-1 and alamar blue...
October 10, 2017: Oncotarget
Mariko Hatta, Christopher I Measures, Jaromir Jarda Ruzicka
Automation of reagent based assays by Flow Injection is based on sample processing, in which a sample flows continuously towards and through a detector for monitoring of its components. There are three drawbacks to using this approach. The constant continuous forward flow: continually consumes reagents and generates chemical waste and necessitates a compromise when optimizing the performance of the reagent based assay. The reason is that individual steps of an assay protocol, i.e., sample and reagent metering, mixing, incubation, monitoring and efficient washout are carried out most efficiently on different time scales and therefore at different flowrates...
February 1, 2018: Talanta
Hua Zhang, Zhen Lei, Rongrong Tian, Zhenxin Wang
Telomerase is extensively expressed in various cancer cells and recognized as a target for cancer drug discovery. In the present study, a simple and amplification-free fluorescence assay based on polyamidoamine starburst dendrimer (PAMAM dendrimer)-activated paper device is proposed for sensitive detection of telomerase activity through hybridization of Cy5 modified single strand DNA probes with telomerase extension products. The paper substrate is fabricated by hand drawing according to a template, which is low cost, instrument free and easy operation...
February 1, 2018: Talanta
Sveva Castelli, Stefania Arasi, Ruby Pawankar, Paolo M Matricardi
PURPOSE OF REVIEW: The identification of immunological markers in nasal secretions and tears is becoming essential in the study of allergic diseases. The collection procedure of nasal and ocular secretions directly influences the results, thus it is of paramount importance to validate and standardize the sampling process. RECENT FINDINGS: Current techniques for nasal secretions sampling are mainly based on three principles: collection of spontaneous secretions, nasal washings, and absorption...
November 14, 2017: Current Opinion in Allergy and Clinical Immunology
Sudkate Chaiyo, Eda Mehmeti, Weena Siangproh, Thai Long Hoang, Hai Phong Nguyen, Orawon Chailapakul, Kurt Kalcher
We introduce for the first time a paper-based analytical device (PAD) for the non-enzymatic detection of glucose by modifying a screen-printed carbon electrode with cobalt phthalocyanine, graphene and an ionic liquid (CoPc/G/IL/SPCE). The modifying composite was characterized by UV-visible spectroscopy, energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The disposable devices show excellent conductivity and fast electron transfer kinetics...
November 9, 2017: Biosensors & Bioelectronics
Huaping Deng, Xiaoming Zhou, Qianwen Liu, Bofan Li, Hongxing Liu, Ru Huang, Da Xing
Small RNAs have been considered as potential biomarkers of various human diseases. Sensitive and multiplexed determination of small RNAs with point-of-care (POC) assay would be of great significance. Herein, an integrated paperfluidic chip device for multiplexed small RNA analysis was developed for the first time. In this system, the extraction and purification of small RNA was completed through a poly(ether sulfone) (PES) paper chip without the need for centrifugation. Subsequently, a newly designed hairpin probe-exponential amplification reaction (HP-EXPAR) was directly performed within the extraction paper chip...
November 15, 2017: ACS Applied Materials & Interfaces
Jason Yong, Basem Hassan, You Liang, Kumaravelu Ganesan, Ranjith Rajasekharan, Robin Evans, Gary Egan, Omid Kavehei, Jingliang Li, Gursharan Chana, Babak Nasr, Efstratios Skafidas
Today's electronic devices are fabricated using highly toxic materials and processes which limits their applications in environmental sensing applications and mandates complex encapsulation methods in biological and medical applications. This paper proposes a fully resorbable high density bio-compatible and environmentally friendly solution processable memristive crossbar arrays using silk fibroin protein which demonstrated bipolar resistive switching ratio of 10(4) and possesses programmable device lifetime characteristics before the device gracefully bio-degrades, minimizing impact to environment or to the implanted host...
November 7, 2017: Scientific Reports
Weirui Tan, Liyuan Zhang, Wei Shen
Chemical-responsive adhesive sensing chip is a new low-cost analytical platform, which uses adhesive tape loaded with indicator reagents to detect or quantify the target analytes by directly sticking the tape to the samples of interest. The chemical-responsive adhesive sensing chips can be used with paper to analyse aqueous samples; they can also be used to detect and quantify solid, particulate and powder analytes. The colorimetric indicators become immediately visible as the contact between the functionalized adhesives and target samples was made...
November 8, 2017: ACS Applied Materials & Interfaces
Zhiwen Zeng, Xiumei Mo
In this paper, a novel chitosan derivative, thiol-grafting bio-inspired catechol-conjugated chitosan was synthesized. The chemical structure of the synthesized catechol-conjugated chitosan was verified by (1)H NMR, and its contents of thiol group and catechol group were determined by UV-vis spectrum. Four percent of catechol-conjugated chitosan aqueous solution could form hydrogels rapidly in situ in 1 min or less with the addition of sodium periodate. Rheological studies showed that the mechanical properties depend on the concentrations of catechol-conjugated chitosan and the molar ratio of sodium periodate to catechol groups...
November 2017: Journal of Biomaterials Applications
Louise Basmaciyan, Nadine Azas, Magali Casanova
Although leishmaniases are responsible for high morbidity and mortality all over the world, no really satisfying treatment exists. Furthermore, the corresponding parasite Leishmania undergoes a very characteristic form of programmed cell death. Indeed, different stimuli can induce morphological and biochemical apoptotic-like features. However, the key proteins involved in mammal apoptosis, such as caspases and death receptors, are not encoded in the genome of this parasite. Currently, little is known about Leishmania apoptosis, notably owing to the lack of specific tools for programmed cell death analysis in these parasites...
2017: PloS One
Suphasinee Sateanchok, Sunanta Wangkarn, Chalermpong Saenjum, Kate Grudpan
A cost-effective assay for antioxidant using simple cotton thread combining paper based device with mobile phone detection has been investigated. Standard and sample solutions flow along a bunch of cotton thread treated with sodium hydroxide via microfluidic behaviors without external pumping. The analyte solution reacts with the reagents that have been immobilized on the paper strip fixed at the end of the cotton bunch. The developed platforms were used for the assays of total phenolic content and antioxidant capacity by employing Folin-Ciocalteu and 2, 2-diphenyl-1-picryhydrazyl (DPPH) respectively...
January 15, 2018: Talanta
Pattarachaya Preechakasedkit, Weena Siangproh, Nanthika Khongchareonporn, Nattaya Ngamrojanavanich, Orawon Chailapakul
In this study, a novel wax-printed paper-based lateral flow device has been developed as an alternative approach for an automated and one-step enzyme-linked immunosorbent assay (ELISA). The design pattern consisted of a non-delayed channel, a wax-delayed channel, a test zone and a control zone. This system was easily fabricated on a nitrocellulose membrane using a wax-printing method and then baked in an oven at 100°C for 1min. The four barriers of the wax-delayed channel could delay the flow time for 11s compared to the flow time of the non-delayed channel...
November 1, 2017: Biosensors & Bioelectronics
Eric Lepowsky, Fariba Ghaderinezhad, Stephanie Knowlton, Savas Tasoglu
A transformation of the healthcare industry is necessary and imminent: hospital-centered, reactive care will soon give way to proactive, person-centered care which focuses on individuals' well-being. However, this transition will only be made possible through scientific innovation. Next-generation technologies will be the key to developing affordable and accessible care, while also lowering the costs of healthcare. A promising solution to this challenge is low-cost continuous health monitoring; this approach allows for effective screening, analysis, and diagnosis and facilitates proactive medical intervention...
September 2017: Biomicrofluidics
Ana Luiza Chaves Maia, Carolina de Aguiar Ferreira, André Luis Branco de Barros, Aline Teixeira Maciel E Silva, Gilson Andrade Ramaldes, Armando da Silva Cunha, Diogo Coelho de Pádua Oliveira, Christian Fernandes, Daniel Crístian Ferreira Soares
Despite advances in the development of new therapeutic agents and diagnostic imaging techniques, the 5-year survival of osteosarcoma, the most common type of bone cancer, remains practically unaltered for the last three decades at around 60%. Nanoparticle-based carriers have emerged as new class of drug delivery systems that could potentially overcome conventional chemotherapy limitations, by promoting a better drug biodistribution profile by allowing a preferential accumulation of the drug in the desired tissue, while minimizing non-targeted tissue toxicity, thus resulting in an improved overall therapeutic effectiveness...
November 3, 2017: Journal of Drug Targeting
Stephanie A Hice, Miguel C Santoscoy, Michelle L Soupir, Rebecca Cademartiri
Switching between metabolically active and dormant states provides bacteria with protection from environmental stresses and allows rapid growth under favorable conditions. This rapid growth can be detrimental to the environment, e.g., pathogens in recreational lakes, or to industrial processes, e.g., fermentation, making it useful to quickly determine when the ratio of dormant to metabolically active bacteria changes. While a rapid increase in metabolically active bacteria can cause complications, a high number of dormant bacteria can also be problematic, since they can be more virulent and antibiotic-resistant...
November 2, 2017: Applied Microbiology and Biotechnology
Emma H Yee, Shefali Lathwal, Pratik P Shah, Hadley D Sikes
We report methods for stabilizing cellulose-based immunoassays and using this platform to analyze human saliva. Stabilization treatments of immunoassays for matrix metalloproteinases (MMP)-8 and -9, biomarkers of periodontal disease, were conducted and compared, revealing that anti-MMP-8 and -9 capture antibodies could be stabilized with the addition of a 5% trehalose solution to the test zones, followed by drying in a vacuum oven. After stabilization, the paper devices retained equivalent binding activity to that of freshly prepared tests for 14 days-a time frame that enables US-based clinical testing of this diagnostic assay...
November 13, 2017: ACS Sensors
Jaione Tirapu-Azpiroz, Yuksel Temiz, Emmanuel Delamarche
Multiplexing assays using microbeads in microfluidics offers high flexibility and throughput, but requires the ability to sort particles based on their physical properties. In this paper, we present a continuous method for separating microbeads that is compact, modular and adaptive, employing an optimized electrode layout that alternates sorting and concentration of microbeads using dielectrophoresis and a nested design. By simulating the combined effects of the hydrodynamic drag and dielectrophoresis forces on polystyrene beads, the parameters of the electrode layout and voltage configuration are optimized for maximum separation based on particle size with a small number of slanted planar electrodes...
October 30, 2017: Biomedical Microdevices
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