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https://www.readbyqxmd.com/read/28715388/measuring-the-densities-of-aqueous-glasses-at-cryogenic-temperatures
#1
Chen Shen, Ethan F Julius, Timothy J Tyree, Ritwik Dan, David W Moreau, Robert Thorne
We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid cooling, to prepare the desired cryogenic temperature phase. Microliter to picoliter size drops are cooled by projection into a liquid nitrogen-argon (N2-Ar) mixture. The cryogenic temperature phase of the drop is evaluated using a visual assay that correlates with X-ray diffraction measurements. The density of the liquid N2-Ar mixture is adjusted by adding N2 or Ar until the drop becomes neutrally buoyant...
June 28, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28701744/massively-parallel-whole-genome-amplification-for-single-cell-sequencing-using-droplet-microfluidics
#2
Masahito Hosokawa, Yohei Nishikawa, Masato Kogawa, Haruko Takeyama
Massively parallel single-cell genome sequencing is required to further understand genetic diversities in complex biological systems. Whole genome amplification (WGA) is the first step for single-cell sequencing, but its throughput and accuracy are insufficient in conventional reaction platforms. Here, we introduce single droplet multiple displacement amplification (sd-MDA), a method that enables massively parallel amplification of single cell genomes while maintaining sequence accuracy and specificity. Tens of thousands of single cells are compartmentalized in millions of picoliter droplets and then subjected to lysis and WGA by passive droplet fusion in microfluidic channels...
July 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28701267/development-of-capillary-liquid-chromatography-a-personal-perspective
#3
REVIEW
Milos V Novotny
This is a historical account on the development of capillary LC from its beginning to the present day. The first investigations into the viability of capillary LC date back to the late 1970s, a decade after the pioneering efforts in HPLC. The drastically reduced column dimensions were required to counter the slow solute diffusion in liquids. There were numerous instrumental difficulties with sample introduction and detection in the picoliter or even femtoliter volumes. High-efficiency separations were needed in the analysis of complex biological mixtures...
June 24, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28667971/controllable-picoliter-pipetting-using-hydrophobic-microfluidic-valves
#4
M Zhang, J Huang, X Qian, S Mi, X Wang
A picoliter pipetting technique using the microfluidic method is presented. Utilizing the hydrophobic self-assembled monolayer films patterned in microchannels as pressure-controlled valves, a small volume of liquid can be separated by a designed channel trap and then ejected from the channel end at a higher pressure. The liquid trap section is composed of a T-shaped channel junction and a hydrophobic patch. The liquid volume can be precisely controlled by varying the distance of the hydrophobic patch from the T-junction...
June 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28609716/accelerating-bacterial-growth-detection-and-antimicrobial-susceptibility-assessment-in-integrated-picoliter-droplet-platform
#5
Aniruddha M Kaushik, Kuangwen Hsieh, Liben Chen, Dong Jin Shin, Joseph C Liao, Tza-Huei Wang
There remains an urgent need for rapid diagnostic methods that can evaluate antibiotic resistance for pathogenic bacteria in order to deliver targeted antibiotic treatments. Toward this end, we present a rapid and integrated single-cell biosensing platform, termed dropFAST, for bacterial growth detection and antimicrobial susceptibility assessment. DropFAST utilizes a rapid resazurin-based fluorescent growth assay coupled with stochastic confinement of bacteria in 20 pL droplets to detect signal from growing bacteria after 1h incubation, equivalent to 2-3 bacterial replications...
November 15, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28604851/analysis-of-ribonuclease-activity-in-sub-nanoliter-droplets-by-label-free-fluorescence-measurements
#6
Jae-Won Choi, Bala Murali Krishna Vasamsetti, Kyu-Wan Kim, Seung Hwan Seo, Dong-Hun Lee, Soo-Ik Chang, Jaebum Choo, Hak Yong Kim
We report the results of a label-free analysis of ribonuclease activity using droplet-based microfluidics. The ribonucleolytic activity of ribonucleases (RNases) plays a critical role in cellular functions such as development, survival, growth and differentiation. Altered ribonucleolytic activity and/or the expression level of the RNase A family are known to be associated with pancreatic, bladder, ovarian and thyroid cancers among others. For this reason, the RNase A family is a meaningful protein biomarker that can be used in the diagnosis of cancer and as a target for new drug screening...
July 10, 2017: Analyst
https://www.readbyqxmd.com/read/28569852/micro-sized-tunable-liquid-crystal-optical-filters
#7
Caleb Stoltzfus, Russell Barbour, David Atherton, Zeb Barber
Liquid crystal arrayed microcavities (LCAM) is a new technology for ultra-narrow optical filtering (FWHM ∼0.1  nm) that uses picoliter volume Fabry-Perot-type optical cavities filled with liquid crystal for tuning. LCAMs are sub-nm spectral resolution filters, which utilize well-established laser writing, thin film deposition, and wafer manufacturing techniques. These filters are compact, robust, and inexpensive. Compact, high-resolution optical filters have applications, including biomedical imaging, chemical detection, and environmental monitoring...
June 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28532147/development-of-a-bacterial-biosensor-for-rapid-screening-of-yeast-p-coumaric-acid-production
#8
Solvej Siedler, Narendar K Khatri, Andrea Zsohár, Inge Kjærbølling, Michael Vogt, Petter Hammar, Christian F Nielsen, Jan Marienhagen, Morten O A Sommer, Haakan N Joensson
Transcription factor-based biosensors are used to identify producer strains, a critical bottleneck in cell factory engineering. Here, we address two challenges with this methodology: transplantation of heterologous transcriptional regulators into new hosts to generate functional biosensors and biosensing of the extracellular product concentration that accurately reflects the effective cell factory production capacity. We describe the effects of different translation initiation rates on the dynamic range of a p-coumaric acid biosensor based on the Bacillus subtilis transcriptional repressor PadR by varying its ribosomal binding site...
June 21, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28527094/circulating-tumor-dna-measurement-by-picoliter-droplet-based-digital-pcr-and-vemurafenib-plasma-concentrations-in-patients-with-advanced-braf-mutated-melanoma
#9
Fanny Garlan, Benoit Blanchet, Nora Kramkimel, Alicja Puszkiel, Jean-Louis Golmard, Gaelle Noe, Nicolas Dupin, Pierre Laurent-Puig, Michel Vidal, Valerie Taly, Audrey Thomas-Schoemann
BACKGROUND: Circulating tumor DNA (ctDNA) has been reported as a prognostic marker in melanoma. In BRAF V600-mutant melanoma, a plasma under-exposure to vemurafenib could favor emerging resistance but no biological data are available to support this hypothesis. OBJECTIVE: We aimed to investigate the relationship between vemurafenib plasma concentrations and the ctDNA plasma concentration during follow-up of BRAF-mutated melanoma patients. PATIENTS AND METHODS: Eleven patients treated with single-agent vemurafenib for advanced BRAF V600-mutant melanoma were analyzed in an exploratory monocentric study...
May 19, 2017: Targeted Oncology
https://www.readbyqxmd.com/read/28503662/picoliter-volume-inkjet-printing-into-planar-microdevice-reservoirs-for-low-waste-high-capacity-drug-loading
#10
Cade B Fox, Cameron L Nemeth, Rachel W Chevalier, Joshua Cantlon, Derek B Bogdanoff, Jeff C Hsiao, Tejal A Desai
Oral delivery of therapeutics is the preferred route for systemic drug administration due to ease of access and improved patient compliance. However, many therapeutics suffer from low oral bioavailability due to low pH and enzymatic conditions, poor cellular permeability, and low residence time. Microfabrication techniques have been used to create planar, asymmetric microdevices for oral drug delivery to address these limitations. The geometry of these microdevices facilitates prolonged drug exposure with unidirectional release of drug toward gastrointestinal epithelium...
March 2017: Bioengineering & Translational Medicine
https://www.readbyqxmd.com/read/28467848/automated-microfluidic-droplet-based-sample-chopper-for-detection-of-small-fluorescence-differences-using-lock-in-analysis
#11
Jean T Negou, L Adriana Avila, Xiangpeng Li, Tesfagebriel M Hagos, Christopher J Easley
Fluorescence is widely used for small-volume analysis and is a primary tool for on-chip detection in microfluidic devices, yet additional expertise, more elaborate optics, and phase-locked detectors are needed for ultrasensitive measurements. Recently, we designed a microfluidic analog to an optical beam chopper (μChopper) that alternated formation of picoliter volume sample and reference droplets. Without complex optics, the device negated large signal drifts (1/f noise), allowing absorbance detection in a mere 27 μm optical path...
June 6, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28450257/a-multifunctional-microfluidic-platform-for-generation-trapping-and-release-of-droplets-in-a-double-laminar-flow
#12
Maria Pilar Carreras, Sihong Wang
Droplet microfluidics, involving micrometer-sized emulsion of droplets is a growing subfield of microfluidics which attracts broad interest due to its application on biological assays. Droplet-based systems have been used as microreactors as well as to encapsulate many biological entities for biomedical and biotechnological applications. Here, a novel microfluidic device is presented for the generation, trapping and release of aqueous including hydrogel droplets in a double laminar oil flow. This platform enables the storage and release of picoliter-sized droplets in two different carrier oils by using hydrodynamic forces without the need of electrical forces or optical actuators...
April 25, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28434824/multiple-pathogen-biomarker-detection-using-an-encoded-bead-array-in-droplet-pcr
#13
Prem Kumar Periyannan Rajeswari, Lovisa M Soderberg, Alia Yacoub, Mikael Leijon, Helene Andersson Svahn, Haakan N Joensson
We present a droplet PCR workflow for detection of multiple pathogen DNA biomarkers using fluorescent color-coded Luminex® beads. This strategy enables encoding of multiple singleplex droplet PCRs using a commercially available bead set of several hundred distinguishable fluorescence codes. This workflow provides scalability beyond the limited number offered by fluorescent detection probes such as TaqMan probes, commonly used in current multiplex droplet PCRs. The workflow was validated for three different Luminex bead sets coupled to target specific capture oligos to detect hybridization of three microorganisms infecting poultry: avian influenza, infectious laryngotracheitis virus and Campylobacter jejuni...
April 20, 2017: Journal of Microbiological Methods
https://www.readbyqxmd.com/read/28396245/application-of-a-handheld-nir-spectrometer-in-prediction-of-drug-content-in-inkjet-printed-orodispersible-formulations-containing-prednisolone-and-levothyroxine
#14
Hossein Vakili, Henrika Wickström, Diti Desai, Maren Preis, Niklas Sandler
Quality control tools to assess the quality of printable orodispersible formulations are yet to be defined. Four different orodispersible dosage forms containing two poorly soluble drugs, levothyroxine and prednisolone, were produced on two different edible substrates by piezoelectric inkjet printing. Square shaped units of 4cm(2) were printed in different resolutions to achieve an escalating drug dose by highly accurate and uniform displacement of droplets in picoliter range from the printhead onto the substrates...
April 7, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28393168/micro-extended-nano-sampling-interface-from-a-living-single-cell
#15
L Lin, K Mawatari, K Morikawa, Y Pihosh, A Yoshizaki, T Kitamori
Single-cell analysis is of increasing importance in many fields, but is challenging due to the ultra-small volumes (picoliters) of single cells. Indeed, analysis of a specific analyte might require the analysis of a single molecule or several molecules. Analytical processes usually include sampling, chemical processing, and detection. Although several papers have reported chemical processing and detection methods for single cells, a sampling method compatible with maintaining the viability of a single cell during sampling has yet to be developed...
April 10, 2017: Analyst
https://www.readbyqxmd.com/read/28390246/exploring-sequence-space-in-search-of-functional-enzymes-using-microfluidic-droplets
#16
REVIEW
Philip Mair, Fabrice Gielen, Florian Hollfelder
Screening of enzyme mutants in monodisperse picoliter compartments, generated at kilohertz speed in microfluidic devices, is coming of age. After a decade of proof-of-principle experiments, workflows have emerged that combine existing microfluidic modules to assay reaction progress quantitatively and yield improved enzymes. Recent examples of the screening of libraries of randomised proteins and from metagenomic sources suggest that this approach is not only faster and cheaper, but solves problems beyond the feasibility scope of current methodologies...
April 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/28363018/single-cell-mass-spectrometry-of-metabolites-extracted-from-live-cells-by-fluidic-force-microscopy
#17
Orane Guillaume-Gentil, Timo Rey, Patrick Kiefer, Alfredo J Ibáñez, Robert Steinhoff, Rolf Brönnimann, Livie Dorwling-Carter, Tomaso Zambelli, Renato Zenobi, Julia A Vorholt
Single-cell metabolite analysis provides valuable information on cellular function and response to external stimuli. While recent advances in mass spectrometry reached the sensitivity required to investigate metabolites in single cells, current methods commonly isolate and sacrifice cells, inflicting a perturbed state and preventing complementary analyses. Here, we propose a two-step approach that combines nondestructive and quantitative withdrawal of intracellular fluid with subpicoliter resolution using fluidic force microscopy, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry...
April 11, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28350406/power-free-digital-and-programmable-dispensing-of-picoliter-droplets-using-a-digit-chip
#18
A Mepham, J D Besant, A W Weinstein, I B Burgess, E H Sargent, S O Kelley
There is a growing need for power-free methods to manipulate small volumes of liquids and thereby enable use of diagnostic assays in resource-limited settings. Most existing self-powered devices provide analog manipulation of fluids using paper, capillary or pressure-driven pumps. These strategies are well-suited to manipulating larger micro- and milliliter-scale volumes at constant flow rates; however, they fail to enable the manipulation of nanoliter and picoliter volumes required in assays using droplets, capillary sampling (e...
April 11, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28346890/high-throughput-system-wide-engineering-and-screening-for-microbial-biotechnology
#19
REVIEW
Yannick Vervoort, Alicia Gutiérrez Linares, Miguel Roncoroni, Chengxun Liu, Jan Steensels, Kevin J Verstrepen
Genetic engineering and screening of large number of cells or populations is a crucial bottleneck in today's systems biology and applied (micro)biology. Instead of using standard methods in bottles, flasks or 96-well plates, scientists are increasingly relying on high-throughput strategies that miniaturize their experiments to the nanoliter and picoliter scale and the single-cell level. In this review, we summarize different high-throughput system-wide genome engineering and screening strategies for microbes...
March 24, 2017: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/28225099/ultra-high-throughput-detection-1-million-droplets-per-second-of-fluorescent-droplets-using-a-cell-phone-camera-and-time-domain-encoded-optofluidics
#20
Venkata R Yelleswarapu, Heon-Ho Jeong, Sagar Yadavali, David Issadore
Droplet-based assays-in which ultra-sensitive molecular measurements are made by performing millions of parallel experiments in picoliter droplets-have generated enormous enthusiasm due to their single molecule resolution and robustness to reaction conditions. These assays have great untapped potential for point of care diagnostics but are currently confined to laboratory settings due to the instrumentation necessary to serially generate, control, and measure tens of millions of droplets. To address this challenge, we have developed the microdroplet megascale detector (μMD) that can generate and detect the fluorescence of millions of droplets per second (1000× faster than conventional approaches) using only a conventional cell phone camera...
March 14, 2017: Lab on a Chip
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