Microfluidics News
Rapid, Sensitive, and Quantitative Detection of Pathogenic DNA at the Point of Care through Microfluidic Electrochemical Quantitative Loop-Mediated Isothermal Amplification
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Kuangwen Hsieh, Adriana S. Patterson, Dr. B. Scott Ferguson, Prof. Kevin W. Plaxco, Prof. H. Tom Soh
Single-step DNA detection: A microfluidic electrochemical loop mediated isothermal amplification platform is reported for rapid, sensitive, and quantitative detection of pathogen genomic DNA at the point of care (see picture). DNA amplification was electrochemically monitored in real time within a monolithic microfluidic device, thus enabling the detection of as few as 16 copies of Salmonella genomic DNA through a single-step process in less than an hour.
Angewandte Chemie International EditionVolume 51, Issue 20, pages 4896–4900, May 14, 2012
DOI: 10.1002/anie.201109115
Light and pH Cooperative Nanofluidic Diode Using a Spiropyran-Functionalized Single Nanochannel
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Minghui Zhang, Xu Hou, Jingtao Wang, Ye Tian, Xia Fan, Jin Zhai, Lei Jiang
An artificial nanofluidic diode system is prepared (see figure), mimicking the light-gated and pH-tunable ion channels that play an important role in life sciences. When UV light is off, the nanochannel is in the closed state, analogous to a resistance. Under UV light irradiation and at pH 7, the current flows from the tip to the base, analogous to a diode
Advanced MaterialsVolume 24, Issue 18, pages 2424–2428, May 8, 2012
One-Step Fabrication of Supramolecular Microcapsules from Microfluidic Droplets
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Jing Zhang, Roger J. Coulston, Samuel T. Jones, Jin Geng, Oren A. Scherman, Chris Abell
Although many techniques exist for preparing microcapsules, it is still challenging to fabricate them in an efficient and scalable process without compromising functionality and encapsulation efficiency. We demonstrated a simple one-step approach that exploits a versatile host-guest system and uses microfluidic droplets to generate porous microcapsules with easily customizable functionality. The capsules comprise a polymer-gold nanoparticle composite held together by cucurbit[8]uril ternary complexes. The dynamic yet highly stable micrometer-sized structures can be loaded in one step during capsule formation and are amenable to on-demand encapsulant release. The internal chemical environment can be probed with surface enhanced Raman spectroscopy.
Science Vol. 335 no. 6069 pp. 690-694
Microfluidic approaches for cancer cell detection, characterization, and separation
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Jian Chen , Jason Li and Yu Sun
This article reviews the recent developments in microfluidic technologies for in vitro cancer diagnosis. We summarize the working principles and experimental results of key microfluidic platforms for cancer cell detection, characterization, and separation based on cell-affinity micro-chromatography, magnetic activated micro-sorting, and cellular biophysics (e.g., cell size and mechanical and electrical properties). We examine the advantages and limitations of each technique and discuss future research opportunities for improving device throughput and purity, and for enabling on-chip analysis of captured cancer cells.
Lab Chip, 2012,12, 1753-1767
Elastomeric microposts integrated into microfluidics for flow-mediated endothelial mechanotransduction analysis
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Raymond H. W. Lam , Yubing Sun , Weiqiang Chen and Jianping Fu
Mechanotransduction is known as the cellular mechanism converting insoluble biophysical signals in the local cellular microenvironment (e.g. matrix rigidity, external mechanical forces, and fluid shear) into intracellular signalling to regulate cellular behaviours. While microfluidic technologies support a precise and independent control of soluble factors in the cellular microenvironment (e.g. growth factors, nutrients, and dissolved gases), the regulation of insoluble biophysical signals in microfluidics, especially matrix rigidity and adhesive pattern, has not yet been achieved. Here we reported an integrated soft lithography-compatible microfluidic methodology that could enable independent controls and modulations of fluid shear, substrate rigidity, and adhesive pattern in a microfluidic environment, by integrating micromolded elastomeric micropost arrays and microcontact printing with microfluidics. The geometry of the elastomeric micropost array could be regulated to mediate substrate rigidity and adhesive pattern, and further the elastomeric microposts could be utilized as force sensors to map live-cell subcellular contractile forces. To illustrate the general application of our methodology, we investigated the flow-mediated endothelial mechanotransduction process and examined specifically the involvement of subcellular contractile forces in the morphological realignment process of endothelial cells under a sustained directional fluid shear. Our results showed that the cytoskeletal contractile forces of endothelial cells were spatiotemporally regulated and coordinated to facilitate their morphology elongation process along the direction of flow. Together, our study provided an integrated microfluidic strategy to modulate the in vitro cellular microenvironment with both defined soluble and insoluble signals, and we demonstrated its application to investigate quantitatively the involvement of cytoskeletal contractile forces in the flow-mediated mechanotransduction process of endothelial cells.
Lab Chip, 2012,12, 1865-1873
Characterization of a microfluidic in vitro model of the blood-brain barrier (μBBB)
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Ross Booth and Hanseup Kim
The blood-brain barrier (BBB), a unique selective barrier for the central nervous system (CNS), hinders the passage of most compounds to the CNS, complicating drug development. Innovative in vitro models of the BBB can provide useful insights into its role in CNS disease progression and drug delivery. Static transwell models lack fluidic shear stress, while the conventional dynamic in vitro BBB lacks a thin dual cell layer interface. To address both limitations, we developed a microfluidic blood-brain barrier (μBBB) which closely mimics the in vivo BBB with a dynamic environment and a comparatively thin culture membrane (10 μm). To test validity of the fabricated BBB model, μBBBs were cultured with b.End3 endothelial cells, both with and without co-cultured C8-D1A astrocytes, and their key properties were tested with optical imaging, trans-endothelial electrical resistance (TEER), and permeability assays. The resultant imaging of ZO-1 revealed clearly expressed tight junctions in b.End3 cells, Live/Dead assays indicated high cell viability, and astrocytic morphology of C8-D1A cells were confirmed by ESEM and GFAP immunostains. By day 3 of endothelial culture, TEER levels typically exceeded 250 Ω cm2 in μBBB co-cultures, and 25 Ω cm2 for transwell co-cultures. Instantaneous transient drop in TEER in response to histamine exposure was observed in real-time, followed by recovery, implying stability of the fabricated μBBB model. Resultant permeability coefficients were comparable to previous BBB models, and were significantly increased at higher pH (>10). These results demonstrate that the developed μBBB system is a valid model for some studies of BBB function and drug delivery.
Lab Chip, 2012,12, 1784-1792
Hierarchical and Multifunctional Three-Dimensional Network of Carbon Nanotubes for Microfluidic Applications
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Three-Dimensional network of carbon nanotubes: The 3D network of CNTs have hierarchical structures comprised of interconnected SWNTs between Si pillars in microfluidic channels. The Al2O3 coated 3D networks were used for size different nanoparticles filtration and streptavidin capturing in very diluted solution. The 3D network of SWNTs systems will provide a robust multifuncitonal platform for a variety of biomedical and environmental applications.
Performance and scaling effects in a multilayer microfluidic extracorporeal lung oxygenation device
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Microfluidic fabrication technologies are emerging as viable platforms for extracorporeal lung assist devices and oxygenators for cardiac surgical support and critical care medicine, based in part on their ability to more closely mimic the architecture of the human vasculature than existing technologies. In comparison with current hollow fiber oxygenator technologies, microfluidic systems have more physiologically-representative blood flow paths, smaller cross section blood conduits and thinner gas transfer membranes. These features can enable smaller device sizes and a reduced blood volume in the oxygenator, enhanced gas transfer efficiencies, and may also reduce the tendency for clotting in the system. Several critical issues need to be addressed in order to advance this technology from its current state and implement it in an organ-scale device for clinical use. Here we report on the design, fabrication and characterization of multilayer microfluidic oxygenators, investigating scaling effects associated with fluid mechanical resistance, oxygen transfer efficiencies, and other parameters in multilayer devices. Important parameters such as the fluidic resistance of interconnects are shown to become more predominant as devices are scaled towards many layers, while other effects such as membrane distensibility become less significant. The present study also probes the relationship between blood channel depth and membrane thickness on oxygen transfer, as well as the rate of oxygen transfer on the number of layers in the device. These results contribute to our understanding of the complexity involved in designing three-dimensional microfluidic oxygenators for clinical applications.
Lab Chip, 2012, 12, 1686-1695
