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Microfluidics

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https://www.readbyqxmd.com/read/29457609/feedback-control-of-photoresponsive-fluid-interfaces
#1
Josua Grawitter, Holger Stark
Photoresponsive surfactants provide a unique microfluidic driving mechanism. Since they switch between two molecular shapes under illumination and thereby affect surface tension of fluid interfaces, Marangoni flow along the interface occurs. To describe the dynamics of the surfactant mixture at a planar interface, we formulate diffusion-advection-reaction equations for both surfactant densities. They also include adsorption from and desorption into the neighboring fluids and photoisomerization by light. We then study how the interface responds when illuminated by spots of light...
February 19, 2018: Soft Matter
https://www.readbyqxmd.com/read/29455527/mechanical-division-of-cell-sized-liposomes
#2
Siddharth Deshpande, Willem Kasper Spoelstra, Marleen van Doorn, Jacob Kerssemakers, Cees Dekker
Liposomes, self-assembled vesicles with a lipid-bilayer boundary similar to cell membranes, are extensively used in both fundamental and applied sciences. Manipulation of their physical properties, such as growth and division, may significantly expand their use as model systems in cellular and synthetic biology. Several approaches have been explored to controllably divide liposomes, such as shape transformation through temperature cycling, incorporation of additional lipids, and the encapsulation of protein division machinery...
February 18, 2018: ACS Nano
https://www.readbyqxmd.com/read/29455024/all-carbon-suspended-nanowire-sensors-as-a-rapid-highly-sensitive-label-free-chemiresistive-biosensing-platform
#3
Aung Thiha, Fatimah Ibrahim, Shalini Muniandy, Ignatius Julian Dinshaw, Swe Jyan Teh, Kwai Lin Thong, Bey Fen Leo, Marc Madou
Nanowire sensors offer great potential as highly sensitive electrochemical and electronic biosensors because of their small size, high aspect ratios, and electronic properties. Nevertheless, the available methods to fabricate carbon nanowires in a controlled manner remain limited to expensive techniques. This paper presents a simple fabrication technique for sub-100 nm suspended carbon nanowire sensors by integrating electrospinning and photolithography techniques. Carbon Microelectromechanical Systems (C-MEMS) fabrication techniques allow fabrication of high aspect ratio carbon structures by patterning photoresist polymers into desired shapes and subsequent carbonization of resultant structures by pyrolysis...
February 9, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29453454/a-microvascularized-tumor-mimetic-platform-for-assessing-anti-cancer-drug-efficacy
#4
Shantanu Pradhan, Ashley M Smith, Charles J Garson, Iman Hassani, Wen J Seeto, Kapil Pant, Robert D Arnold, Balabhaskar Prabhakarpandian, Elizabeth A Lipke
Assessment of anti-cancer drug efficacy in in vitro three-dimensional (3D) bioengineered cancer models provides important contextual and relevant information towards pre-clinical translation of potential drug candidates. However, currently established models fail to sufficiently recapitulate complex tumor heterogeneity. Here we present a chip-based tumor-mimetic platform incorporating a 3D in vitro breast cancer model with a tumor-mimetic microvascular network, replicating the pathophysiological architecture of native vascularized breast tumors...
February 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29453278/molecular-signatures-of-circulating-melanoma-cells-for-monitoring-early-response-to-immune-checkpoint-therapy
#5
Xin Hong, Ryan J Sullivan, Mark Kalinich, Tanya Todorova Kwan, Anita Giobbie-Hurder, Shiwei Pan, Joseph A LiCausi, John D Milner, Linda T Nieman, Ben S Wittner, Uyen Ho, Tianqi Chen, Ravi Kapur, Donald P Lawrence, Keith T Flaherty, Lecia V Sequist, Sridhar Ramaswamy, David T Miyamoto, Michael Lawrence, Mehmet Toner, Kurt J Isselbacher, Shyamala Maheswaran, Daniel A Haber
A subset of patients with metastatic melanoma have sustained remissions following treatment with immune checkpoint inhibitors. However, analyses of pretreatment tumor biopsies for markers predictive of response, including PD-1 ligand (PD-L1) expression and mutational burden, are insufficiently precise to guide treatment selection, and clinical radiographic evidence of response on therapy may be delayed, leading to some patients receiving potentially ineffective but toxic therapy. Here, we developed a molecular signature of melanoma circulating tumor cells (CTCs) to quantify early tumor response using blood-based monitoring...
February 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29453167/electrochemical-detection-of-methylated-dna-on-a-microfluidic-chip-with-nanoelectrokinetic-pre-concentration
#6
Sung A Hong, Yong-June Kim, Sung Jae Kim, Sung Yang
DNA methylation is considered to be a promising marker for the early diagnosis and prognosis of cancer. However, direct detection of the methylated DNAs in clinically relevant samples is still challenging because of its extremely low concentration (~fM). Here, an integrated microfluidic chip is reported, which is capable of pre-concentrating the methylated DNAs using ion concentration polarization (ICP) and electrochemically detecting the pre-concentrated DNAs on a single chip. The proposed chip is the first demonstration of an electrochemical detection of both level and concentration of the methylated DNAs by integrating a DNA pre-concentration unit without gene amplification...
February 1, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29452445/suppressive-role-of-tissue-factor-pathway-inhibitor-%C3%AE-in-platelet-dependent-fibrin-formation-under-flow-is-restricted-to-low-procoagulant-strength
#7
Stella Thomassen, Tom G Mastenbroek, Frauke Swieringa, Kristien Winckers, Marion A H Feijge, Roy Schrijver, Judith M E M Cosemans, Susan A Maroney, Alan E Mast, Tilman M Hackeng, Johan W M Heemskerk
Tissue factor pathway inhibitor-alpha (TFPI-α) is a Kunitz-type serine protease inhibitor, which suppresses coagulation by inhibiting the tissue factor (TF)/factor VIIa complex as well as factor Xa. In static plasma-phospholipid systems, TFPI-α thus suppresses both factor Xa and thrombin generation. In this article, we used a microfluidics approach to investigate how TFPI-α regulates fibrin clot formation in platelet thrombi at low wall shear rate. We therefore hypothesized that the anticoagulant effect of TFPI-α in plasma is a function of the local procoagulant strength-defined as the magnitude of thrombin generation under flow, due to local activities of TF/factor VIIa and factor Xa...
February 16, 2018: Thrombosis and Haemostasis
https://www.readbyqxmd.com/read/29451779/real-time-intrinsic-fluorescence-visualisation-and-sizing-of-proteins-and-protein-complexes-in-microfluidic-devices
#8
Pavan Kumar Challa, Quentin Peter, Maya A Wright, Yuewen Zhang, Kadi-Liis Saar, Jacqueline A Carozza, Justin L P Benesch, Tuomas P J Knowles
Optical detection has become a convenient and scalable approach to read out information from microfluidic systems. For the study of many key biomolecules, however, including peptides and proteins, which have low fluorescence emission efficiencies at visible wavelengths, this approach typically requires labelling of the species of interest with extrinsic fluorophores to enhance the optical signal obtained -- a process which can be time-consuming, requires purification steps, and has the propensity to perturb the behaviour of the systems under study due to interactions between the labels and the analyte molecules...
February 16, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29451404/optimizing-nbe-pk-pd-assays-using-the-gyrolab-affinity-software-conveniently-within-the-bioanalyst-s-existing-workflow
#9
Maria Myzithras, Tammy Bigwarfe, Erica Waltz, Hua Li, Jennifer Ahlberg, Irina Rybina, Sarah Low, Cynthia Hess Kenny, John Miglietta, Rachel Kroe-Barrett
AIM: The fully automated microfluidics-based Gyrolab is a popular instrument for the bioanalysis of protein therapeutics; requiring minimal sample and reagent volumes. Gyros offers affinity software for determining binding affinity in solution using a high-throughput method and miniaturized reactions. RESULTS: Using this affinity software, multiple CTGF-targeting reagents were characterized on the Gyrolab after <100% target coverage was seen in a cynomolgus pharmacokinetic/PD study dosed with anti-CTGF antibodies...
February 16, 2018: Bioanalysis
https://www.readbyqxmd.com/read/29451128/signal-amplifying-nanoparticle-hydrogel-hybrid-microarray-biosensor-for-metal-enhanced-fluorescence-detection-of-organophosphorus-compounds
#10
Minsu Kim, Kangwon Lee, Ji Eon Kwon, Won Gun Koh
In this study, we developed an enzyme-based miniaturized fluorescence biosensor to detect paraoxon, one of the most well-known neurotoxic organophosphorus compounds (OPs). The biosensor was fabricated with poly(ethylene glycol) (PEG) hydrogel microarrays that entrapped acetylcholinesterase (AChE) and quantum dots (QDs) as fluorescence reporters. Metal-enhanced fluorescence (MEF) was utilized to amplify the fluorescence signal, which was achieved by decorating QDs on the surface of silica-coated silver nanoparticles (Ag@Silica)...
February 16, 2018: Biofabrication
https://www.readbyqxmd.com/read/29450440/injection-molded-lab-on-a-disc-platform-for-screening-of-genetically-modified-e-coli-using-liquid-liquid-extraction-and-surface-enhanced-raman-scattering
#11
Lidia Morelli, Laura Serioli, Francesca Alessandra Centorbi, Christian Bille Jendresen, Marco Matteucci, Oleksii Ilchenko, Danilo Demarchi, Alex Toftgaard Nielsen, Kinga Zór, Anja Boisen
We present the development of an automated centrifugal microfluidic platform with integrated sample pre-treatment (filtration and liquid-liquid extraction) and detection (SERS-based sensing). The platform consists of eight calibration and four assay modules, fabricated with polypropylene using injection molding and bonded with ultrasonic welding. The platform was used for detection of a secondary bacterial metabolite (p-coumaric acid) from bacterial supernatant. The obtained extraction efficiency was comparable to values obtained in batch experiments and the SERS-based sensing showed a good correlation with HPLC analysis...
February 16, 2018: Lab on a Chip
https://www.readbyqxmd.com/read/29449156/stochastic-expression-of-lactate-dehydrogenase-a-induces-escherichia-coli-persister-formation
#12
Naoki Yamamoto, Rino Isshiki, Yuto Kawai, Daiki Tanaka, Tetsushi Sekiguchi, Shinya Matsumoto, Satoshi Tsuneda
Bacterial persisters are phenotypic variants that survive the treatment of lethal doses of growth-targeting antibiotics without mutations. Although the mechanism underlying persister formation has been studied for decades, how the persister phenotype is switched on and protects itself from antibiotics has been elusive. In this study, we focused on the lactate dehydrogenase gene (ldhA) that was upregulated in an Escherichia coli persister-enriched population. A survival rate assay using an ldhA-overexpressing strain showed that ldhA expression induced persister formation...
February 12, 2018: Journal of Bioscience and Bioengineering
https://www.readbyqxmd.com/read/29448966/exosomes-taken-up-by-neurons-hijack-the-endosomal-pathway-to-spread-to-interconnected-neurons
#13
Juan Carlos Polanco, Chuanzhou Li, Nela Durisic, Robert Sullivan, Jürgen Götz
In Alzheimer disease and related disorders, the microtubule-associated protein tau aggregates and forms cytoplasmic lesions that impair neuronal physiology at many levels. In addition to affecting the host neuron, tau aggregates also spread to neighboring, recipient cells where the misfolded tau aggregates, in a manner similar to prions, actively corrupt the proper folding of soluble tau, and thereby impair cellular functions. One vehicle for the transmission of tau aggregates are secretory nanovesicles known as exosomes...
February 15, 2018: Acta Neuropathologica Communications
https://www.readbyqxmd.com/read/29448769/nanobubbles-in-confined-solution-generation-contact-angle-and-stability
#14
Jiachen Wei, Xianren Zhang, Fan Song, Yingfeng Shao
The formation of gas bubbles presents a frequent challenge to microfluidic operations, for which fluids are geometrically confined to a microscale space. Here, to understand the mechanism of nucleating gas bubbles in microfluidic devices, we investigate the formation and stability of nanobubbles in confined solutions. Our molecular dynamics simulations show that while pinning of the contact line is a prerequisite for the stability of surface nanobubbles in open systems that can exchange gas with surrounding environment, in confined solutions, stable nanobubbles can exist even without pinning...
February 14, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29448587/droplet-based-microfluidic-reactor-for-synthesis-of-size-controlled-cdse-quantum-dots
#15
Cheol Hwan Kwak, Joong Pill Park, Sung Sil Lee, Rethinasabapathy Muruganantham, Soonjo Kwon, Changhyun Roh, Sang-Wook Kim, Yun Suk Huh
CdSe quantum dots (QDs) with a uniform size distribution were synthesized using a droplet-based microfluidic reactor. The droplet-based microfluidic reactor enabled continuous production of CdSe QDs at a temperature of less than 250 °C in an extremely shorter reaction time (less than 30 s) when compared with the batch reactor. The photoluminescence (PL) and ultraviolet (UV) absorption spectra of the CdSe QDs were recorded at different reaction times and the size and optical properties of the QDs were discussed...
February 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448448/high-speed-broadband-elastic-actuator-in-water-using-induced-charge-electro-osmosis-with-a-skew-structure
#16
Hideyuki Sugioka, Naoki Nakano
An artificial cilium using ac electro-osmosis (ACEO) is attractive because of its large potentiality for innovative microfluidic applications. However, the ACEO cilium has not been probed experimentally and has a shortcoming that the working frequency range is very narrow. Thus, we here propose an ACEO elastic actuator having a skew structure that broadens a working frequency range and experimentally demonstrate that the elastic actuator in water can be driven with a high-speed (∼10 Hz) and a wide frequency range (∼0...
January 2018: Physical Review. E
https://www.readbyqxmd.com/read/29447224/directional-freezing-for-the-cryopreservation-of-adherent-mammalian-cells-on-a-substrate
#17
Liat Bahari, Amir Bein, Victor Yashunsky, Ido Braslavsky
Successfully cryopreserving cells adhered to a substrate would facilitate the growth of a vital confluent cell culture after thawing while dramatically shortening the post-thaw culturing time. Herein we propose a controlled slow cooling method combining initial directional freezing followed by gradual cooling down to -80°C for robust preservation of cell monolayers adherent to a substrate. Using computer controlled cryostages we examined the effect of cooling rates and dimethylsulfoxide (DMSO) concentration on cell survival and established an optimal cryopreservation protocol...
2018: PloS One
https://www.readbyqxmd.com/read/29446618/correction-to-all-in-one-centrifugal-microfluidic-device-for-size-selective-circulating-tumor-cell-isolation-with-high-purity
#18
Ada Lee, Juhee Park, Minji Lim, Vijaya Sunkara, Shine Young Kim, Gwang Ha Kim, Mi-Hyun Kim, Yoon-Kyoung Cho
No abstract text is available yet for this article.
February 15, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29445889/clinical-significance-of-circulating-tumor-cells-from-lung-cancer-patients-using-microfluidic-chip
#19
Chen Qian, Shan Wu, Hongmei Chen, Xiaofen Zhang, Rongrong Jing, Lei Shen, Xudong Wang, Shaoqing Ju, Chunping Jia, Hui Cong
Circulating tumor cells (CTCs) exist in the peripheral blood and have an important role in the disease development, tumor metastasis and clinical surveillance, especially in the process of metastasis. However, the technology of detecting CTCs still had a large challenge since they were rare in the peripheral blood. Here, we developed a size-based microfluidic chip, which contained array and filter channel array that could enrich CTCs from blood samples more quickly and conveniently. Combined with clinical specimen, we analyzed CTCs in 200 lung cancer patients by this microfluidic chip...
February 14, 2018: Clinical and Experimental Medicine
https://www.readbyqxmd.com/read/29445800/acoustic-separation-in-plastic-microfluidics-for-rapid-detection-of-bacteria-in-blood-using-engineered-bacteriophage
#20
P Dow, K Kotz, S Gruszka, J Holder, J Fiering
A more effective treatment of bacteremia requires a diagnostic platform that is both sensitive, accurate and rapid. Currently, clinical laboratory techniques require growth of bacteria prior to diagnosis, take days to complete, and leave empiric therapy and broad spectrum antibiotics as the only option at the onset of treatment. In order to bypass this growth requirement, we engineered a system that purifies bacteria from blood to improve performance in a bacteriophage-based luminescence assay. To perform the purification, we used acoustophoresis in plastic microfluidic chips, enabling future development into a low cost point-of-care system...
February 15, 2018: Lab on a Chip
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