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Paul S Sheeran, Naomi Matsuura, Mark A Borden, Ross Williams, Terry O Matsunaga, Peter N Burns, Paul A Dayton
Continued advances in the field of ultrasound and ultrasound contrast agents have created new approaches to imaging and medical intervention. Phase-shift perfluorocarbon droplets, which can be vaporized by ultrasound energy to transition from the liquid to the vapor state, are one of the most highly researched alternatives to clinical ultrasound contrast agents (i.e. microbubbles). In this review, part of a special issue on methods in biomedical ultrasonics, we survey current techniques to prepare ultrasound-activated nanoscale phase-shift perfluorocarbon droplets, including sonication, extrusion, homogenization, microfluidics, and microbubble condensation...
October 20, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Thomas Chretiennot, David Dubuc, Katia Grenier
This paper presents a reliable microwave and microfluidic miniature sensor dedicated to the measurement of glucose concentration in aqueous solution. The device; which is integrated with microtechnologies; is made of a bandstop filter implemented in a thin film microstrip technology combined with a fluidic microchannel. Glucose aqueous solutions have been characterized for concentration ranging from 80 g/L down to 0.3 g/L and are identified with the normalized insertion loss at optimal frequency. The sensitivity of the sensor has consequently been estimated at 7...
October 19, 2016: Sensors
Ken-Ichiro Kamei, Yoshie Koyama, Yumie Tokunaga, Yasumasa Mashimo, Momoko Yoshioka, Christopher Fockenberg, Rowland Mosbergen, Othmar Korn, Christine Wells, Yong Chen
Human pluripotent stem cells hold great promise for applications in drug discovery and regenerative medicine. Microfluidic technology is a promising approach for creating artificial microenvironments; however, although a proper 3D microenvironment is required to achieve robust control of cellular phenotypes, most current microfluidic devices provide only 2D cell culture and do not allow tuning of physical and chemical environmental cues simultaneously. Here, the authors report a 3D cellular microenvironment plate (3D-CEP), which consists of a microfluidic device filled with thermoresponsive poly(N-isopropylacrylamide)-β-poly(ethylene glycol) hydrogel (HG), which enables systematic tuning of both chemical and physical environmental cues as well as in situ cell monitoring...
October 24, 2016: Advanced Healthcare Materials
Yosuke Iwai, Yoshiaki Uchida, Hiroshi Yabu, Norikazu Nishiyama
Microfluidic devices, which can continuously fabricate single emulsion with monodispersed droplets having a pore diameter of more than 100 μm in large numbers, can be applied to manufacture ordered macroporous films. 3D ordered macroporous films with a diameter of more than 100 μm can be fabricated using ordered arrays of the monodispersed droplets as templates of the macropores, which are self-assembled in the space between two parallel flat glass plates. As the gap between the glass plates increases, the number of the layer increases...
October 24, 2016: Macromolecular Rapid Communications
Kai Zhao, Ran Peng, Dongqing Li
A novel DC-dielectrophoresis (DEP) method employing a pressure-driven flow for the continuous separation of micro/nano-particles is presented in this paper. To generate the DEP force, a small voltage difference is applied to produce a non-uniformity of the electric field across a microchannel via a larger orifice of several hundred microns on one side of the channel wall and a smaller orifice of several hundred nanometers on the opposite channel wall. The particles experience a DEP force when they move with the flow through the vicinity of the small orifice, where the strongest electrical field gradient exists...
October 24, 2016: Nanoscale
Zitian Chen, Yusi Fu, Fangli Zhang, Lu Liu, Naiqing Zhang, Dong Zhou, Junrui Yang, Yuhong Pang, Yanyi Huang
Many on-chip approaches that use flow-focusing to pinch the continuous aqueous phase into droplets have become the most popular methods that provide monodisperse emulsion droplets. However, not every lab can easily adapt a microfluidic workflow into their familiar protocols. We develop an off-chip approach, spinning micro-pipette liquid emulsion (SiMPLE) generator, to produce highly stable monodisperse water-in-oil emulsions using a moving micropipette to disperse the aqueous phase in an oil-filled microcentrifuge tube...
October 24, 2016: Lab on a Chip
Hui Xia, Briony C Strachan, Sean C Gifford, Sergey S Shevkoplyas
Leukocyte reduction of donated blood products substantially reduces the risk of a number of transfusion-related complications. Current 'leukoreduction' filters operate by trapping leukocytes within specialized filtration material, while allowing desired blood components to pass through. However, the continuous release of inflammatory cytokines from the retained leukocytes, as well as the potential for platelet activation and clogging, are significant drawbacks of conventional 'dead end' filtration. To address these limitations, here we demonstrate our newly-developed 'controlled incremental filtration' (CIF) approach to perform high-throughput microfluidic removal of leukocytes from platelet-rich plasma (PRP) in a continuous flow regime...
October 24, 2016: Scientific Reports
Kyung Suk Lee, Lucy E Lee, Erel Levine
Small animals such as the roundworm C. elegans are excellent models for studying bacterial infection and host response, as well as for genetic and chemical screens. A key methodology is the killing assay, in which the number of surviving animals is tracked as a function of the time post infection. This is a labor-intensive procedure, prone to human error and subjective choices, and often involves undesired perturbation to the animals and their environment. In addition, the survival of animals is just one aspect of a multi-dimensional complex biological process...
October 24, 2016: Scientific Reports
Hui Dong, Hao Sun, Jianping Zheng
With the development of large-scale biologic databases, precision medicine is becoming a frontier in biomedical research. As a main focus of precision medicine study, cancer has been widely accepted as a disease born out of inherited genetic variations or accumulating genomic damage. At the single-cell level, microfluidics or lab-on-a-chip technology for cancer study is an emerging tool for improving risk assessment, diagnostic categories and therapeutic strategies. This work presents a multi-layer microchip for single-cell gene expression profiling...
December 1, 2016: Talanta
Natta Wiriyakun, Duangjai Nacapricha, Rattikan Chantiwas
This work presents a simple hot embossing method with a shrinking procedure to produce cross-shape microchannels on poly(methyl methacrylate) (PMMA) substrate for the fabrication of an electrophoresis chip. The proposed method employed a simple two-step hot embossing technique, carried out consecutively on the same piece of substrate to make the crossing channels. Studies of embossing conditions, i.e. temperature, pressure and time, were carried out to investigate their effects on the dimension of the microchannels...
December 1, 2016: Talanta
Pavel Kubáň, Knut Fredrik Seip, Astrid Gjelstad, Stig Pedersen-Bjergaard
This work investigated selective micro-electromembrane extractions (μ-EMEs) of the colored indicators metanil yellow and congo red (visual proof-of-principle) and the small drug substances nortriptyline, papaverine, mianserin, and citalopram (model analytes) based on their acid-base strength. With two free liquid membranes (FLMs), the target analytes were extracted from aqueous donor solution, across FLM 1 (1-pentanol, 1-ethyl-2-nitrobenzene (ENB) or 4-nitrocumene (4-NC)), into aqueous acceptor solution 1, further across FLM 2 (1-pentanol, ENB or 4-NC), and finally into aqueous acceptor solution 2...
November 2, 2016: Analytica Chimica Acta
Arvind Y M Sundaram, Timothy Hughes, Shea Biondi, Nathalie Bolduc, Sarah K Bowman, Andrew Camilli, Yap C Chew, Catherine Couture, Andrew Farmer, John P Jerome, David W Lazinski, Andrew McUsic, Xu Peng, Kamran Shazand, Feng Xu, Robert Lyle, Gregor D Gilfillan
BACKGROUND: ChIP-seq is the primary technique used to investigate genome-wide protein-DNA interactions. As part of this procedure, immunoprecipitated DNA must undergo "library preparation" to enable subsequent high-throughput sequencing. To facilitate the analysis of biopsy samples and rare cell populations, there has been a recent proliferation of methods allowing sequencing library preparation from low-input DNA amounts. However, little information exists on the relative merits, performance, comparability and biases inherent to these procedures...
October 21, 2016: BMC Genomics
Kelly Muijlwijk, Wenqian Huang, Jan-Eise Vuist, Claire Berton-Carabin, Karin Schroën
Surfactant adsorption during emulsification can be quantified by measuring the acting interfacial tension using a Y-junction microfluidic device. To obtain insight into the surfactant transport mechanism to the interface, the effect of shear force on the acting interfacial tension was assessed by systematically varying the continuous phase viscosity and velocity. Varying the continuous phase viscosity did not affect the acting interfacial tension, indicating that surfactant adsorption during Y-junction emulsification is not diffusion-limited...
October 21, 2016: Soft Matter
Po C Liu, Yi T Lee, Chun Y Wang, Ya-Tang Yang
We describe a low cost, configurable morbidostat for characterizing the evolutionary pathway of antibiotic resistance. The morbidostat is a bacterial culture device that continuously monitors bacterial growth and dynamically adjusts the drug concentration to constantly challenge the bacteria as they evolve to acquire drug resistance. The device features a working volume of ~10 ml and is fully automated and equipped with optical density measurement and micro-pumps for medium and drug delivery. To validate the platform, we measured the stepwise acquisition of trimethoprim resistance in Escherichia coli MG 1655, and integrated the device with a multiplexed microfluidic platform to investigate cell morphology and antibiotic susceptibility...
September 27, 2016: Journal of Visualized Experiments: JoVE
K Lee, A Priezzhev, S Shin, Y Francois, I Meglinski
BACKGROUND: The novel measure of the red blood cells (RBC) aggregation (RBC-A) - the critical (minimum) shear stress (CSS) to prevent the cells from aggregation was found to be a promising clinically significant parameter. However, the absolute values of this parameter were found to change significantly depending on the shearing geometry (cup-and-bob, cone-plate or microchannel-flow) and have different temperature dependences along with it. The direct confirmation of these dependences aimed to find out the correct values is still pending...
October 18, 2016: Clinical Hemorheology and Microcirculation
Thitaphat Ngernsutivorakul, Cynthia M Cipolla, Colleen E Dugan, Shi Jin, Michael D Morris, Robert T Kennedy, Francis W L Esmonde-White
Fiber optics coupled to components such as lenses and mirrors have seen extensive use as probes for Raman and fluorescence measurements. Probes can be placed directly on or into a sample to allow for simplified and remote application of these optical techniques. The size and complexity of such probes however limits their application. We have used microfabrication in polydimethylsiloxane (PDMS) to create compact probes that are 0.5 mm thick by 1 mm wide. The miniature probes incorporate pre-aligned mirrors, lenses, and two fiber optic guides to allow separate input and output optical paths suitable for Raman and fluorescence spectroscopy measurements...
October 20, 2016: Analytical and Bioanalytical Chemistry
Brandon L Thompson, Christopher Birch, Daniel A Nelson, Jingyi Li, Jacquelyn A DuVall, Delphine Le Roux, An-Chi Tsuei, Daniel L Mills, Brian E Root, James P Landers
Current conventional methods utilized for forensic DNA analysis are time consuming and labor-intensive requiring large and expensive equipment and instrumentation. While more portable Rapid DNA systems have been developed, introducing them to a working laboratory still necessitates a high cost of initiation followed by the recurrent cost of the devices. This has highlighted the need for an inexpensive, rapid and portable DNA analysis tool for human identification in a forensic setting. In order for an integrated DNA analysis system such as this to be realized, device operations must always be concluded by a rapid separation of short-tandem repeat (STR) DNA fragments...
October 21, 2016: Lab on a Chip
Margherita Bassu, Peter Holik, Sam Schmitz, Siegfried Steltenkamp, Thomas P Burg
Nanofluidic devices exhibit unique, tunable transport properties that may lead to breakthroughs in molecular separations and sensing. However, the throughput of these devices is orders of magnitude too small for the processing of macroscopic samples. Here we overcome this problem by combining two technological innovations. First, nanofluidic channels are made as vertical slits connecting the two sides of a silicon nitride membrane. Arbitrary arrays of such nanoslits down to 15 nm wide with <6 Å uniformity were made by merging the idea of templating with chemical mechanical polishing to create a scalable, nanolithography-free wafer level process...
October 21, 2016: Lab on a Chip
Joshua Giltinan, Eric Diller, Metin Sitti
At the sub-millimeter scale, capillary forces enable robust and reversible adhesion between biological organisms and varied substrates. Current human-engineered mobile untethered micromanipulation systems rely on forces which scale poorly or utilize gripper-part designs that promote manipulation. Capillary forces, alternatively, are dependent upon the surface chemistry (which is scale independent) and contact perimeter, which conforms to the part surface. We report a mobile capillary microgripper that is able to pick and place parts of various materials and geometries, and is thus ideal for microassembly tasks that cannot be accomplished by large tethered manipulators...
October 21, 2016: Lab on a Chip
Yujing Li, Xueqin Huang, Robert J Lee, Yuhang Qi, Kaikai Wang, Fei Hao, Yu Zhang, Jiahui Lu, Qingfan Meng, Shuai Li, Jing Xie, Lesheng Teng
Polyethylenimine (PEI) as a cationic polymer is commonly used as a carrier for gene delivery. PEI-800 is less toxic than PEI-25K but it is also less efficient. A novel nanocarrier was developed by combining PEI-800 with a pH-sensitive lipid to form polymer-lipid hybrid nanoparticles (P/LNPs). They were synthesized by microfluidic focusing (MF). Two microfluidic devices were used to synthesize P/LNPs loaded with VEGF siRNA. A series of P/LNPs with different particle sizes and distributions were obtained by altering the flow rate and geometry of microfluidic chips, and introducing sonication...
October 17, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
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