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Tianqing Zheng, Jia Xie, Zhuo Yang, Pingdong Tao, Bingbing Shi, Lacey Douthit, Peng Wu, Richard A Lerner
We describe a method for the rapid selection of functional antibodies. The method depends on the cocultivation of Escherichia coli that produce phage with target eukaryotic cells in very small volumes. The antibodies on phage induce selectable phenotypes in the target cells, and the nature of the antibody is determined by gene sequencing of the phage genome. To select functional antibodies from the diverse antibody repertoire, we devised a selection platform that contains millions of picoliter-sized droplet ecosystems...
June 18, 2018: Proceedings of the National Academy of Sciences of the United States of America
Ruichuan Yin, Venkateshkumar Prabhakaran, Julia Laskin
Quantitative live cell mass spectrometry analysis at a subcellular level requires the precisely controlled extraction of subpicoliter volumes of material from the cell, sensitive analysis of the extracted analytes, and their accurate quantification without prior separation. In this study, we demonstrate that localized electroosmotic extraction provides a direct path to addressing this challenge. Specifically, we demonstrate quantitative mass spectrometry analysis of biomolecules in picoliter volumes extracted from live cells...
June 6, 2018: Analytical Chemistry
Jui-Chia Chang, Zoe Swank, Oliver Keiser, Sebastian J Maerkl, Esther Amstad
Emulsion drops are often employed as picoliter-sized containers to perform screening assays. These assays usually entail the formation of drops encompassing discrete objects such as cells or microparticles and reagents to study interactions between the different encapsulants. Drops are also used to screen influences of reagent concentrations on the final product. However, these latter assays are less frequently performed because it is difficult to change the reagent concentration over a wide range and with high precision within a single experiment...
May 25, 2018: Scientific Reports
Samantha A Byrnes, Elizabeth A Phillips, Toan Huynh, Bernhard H Weigl, Kevin P Nichols
Microbiological culture remains the most sensitive method for detecting viable and infectious bacteria, but these methods often require at least 24 hours to visibly identify bacterial growth. Lab-on-a-chip applications have utilized methods to isolate bacteria in picoliter-sized reaction vessels, resulting in digitized signals that offer improved time-to-detection and improved quantification. Although a great improvement, these approaches typically require expensive and specialized equipment, trained laboratory personnel, and maximum addressable volumes that can be orders of magnitude less than needed for clinically relevant limits of detection...
May 21, 2018: Analyst
Robert C Dunn
Wavelength modulated back scatter interferometry (M-BSI) is shown to improve the detection metrics for refractive index (RI) sensing in micro-separations. In M-BSI, the output of a tunable diode laser is focused into the detection zone of a separation channel as the excitation wavelength is rapidly modulated. This spatially modulates the observed interference pattern, which is measured in the back-scattered direction. Using a split photodiode detector aligned on one fringe of the of interference pattern, phase-sensitive detection is used to monitor RI changes as analytes are separated...
May 15, 2018: Analytical Chemistry
Elio J Challita, Joseph S Najem, Rachel Monroe, Donald J Leo, Eric C Freeman
The development of membrane-based materials that exhibit the range and robustness of autonomic functions found in biological systems remains elusive. Droplet interface bilayers (DIBs) have been proposed as building blocks for such materials, owing to their simplicity, geometry, and capability for replicating cellular phenomena. Similar to how individual cells operate together to perform complex tasks and functions in tissues, networks of functionalized DIBs have been assembled in modular/scalable networks. Here we present the printing of different configurations of picoliter aqueous droplets in a bath of thermoreversible organogel consisting of hexadecane and SEBS triblock copolymers...
April 24, 2018: Scientific Reports
Mridu Sinha, Hannah Mack, Todd P Coleman, Stephanie I Fraley
DNA melting analysis provides a rapid method for genotyping a target amplicon directly after PCR amplification. To transform melt genotyping into a broad-based profiling approach for heterogeneous samples, we previously proposed the integration of universal PCR and melt analysis with digital PCR. Here, we advanced this concept by developing a high-resolution digital melt platform with precise thermal control to accomplish reliable, high-throughput heat ramping of microfluidic chip digital PCR reactions. Using synthetic DNA oligos with defined melting temperatures, we characterized sources of melting variability and minimized run-to-run variations...
April 1, 2018: SLAS Technology
Xiao-Li Guo, Yan Wei, Qi Lou, Ying Zhu, Qun Fang
Herein, we developed an automated and flexible system for performing miniaturized liquid-liquid reactions and assays in the femtoliter to picoliter range, by combining the contact printing and the droplet-based microfluidics techniques. The system mainly consisted of solid pins and an oil-covered hydrophilic micropillar array chip fixed on an automated x- y- z translation stage. A novel droplet manipulation mode called "dipping-depositing-moving" (DDM) was proposed, which was based on the programmable combination of three basic operations, dipping liquids and depositing liquids with the solid pins and moving the two-dimensional oil-covered hydrophilic pillar microchip...
May 1, 2018: Analytical Chemistry
Hanie Yousefi, M Monsur Ali, Hsuan-Ming Su, Carlos D M Filipe, Tohid F Didar
Here, we report the development of a transparent, durable, and flexible sensing surface that generates a fluorescence signal in the presence of a specific target bacterium. This material can be used in packaging, and it is capable of monitoring microbial contamination in various types of food products in real time without having to remove the sample or the sensor from the package. The sensor was fabricated by covalently attaching picoliter-sized microarrays of an E. coli-specific RNA-cleaving fluorogenic DNAzyme probe (RFD-EC1) to a thin, flexible, and transparent cyclo-olefin polymer (COP) film...
April 24, 2018: ACS Nano
Xuecui Mei, Qinnan Chen, Shihu Wang, Wei Wang, Dezhi Wu, Daoheng Sun
Transportation of highly viscous solutions at the picoliter level with a rapid dynamic response is paramount for micro/nano-fabrication. With the advantages of a higher length-wall (thickness) ratio and a more stable free surface compared to those of the traditional Weissenberg effect (TWE), the microscale Weissenberg effect (MWE) can continuously and controllably pump high-viscosity solutions at the picoliter scale. Some typical characteristics and behaviors of MWE are investigated as the rotation rod diameter decreases to the microscale of ∼100 μm...
April 19, 2018: Nanoscale
Nele Boeckx, Ken Op de Beeck, Matthias Beyens, Vanessa Deschoolmeester, Christophe Hermans, Peggy De Clercq, Sonia Garrigou, Corinne Normand, Els Monsaert, Konstantinos Papadimitriou, Pierre Laurent-Puig, Patrick Pauwels, Guy Van Camp, Valerie Taly, Marc Peeters
BACKGROUND: Targeted therapies, although contributing to survival improvement in metastatic colorectal cancer (mCRC), are expensive and may cause adverse effects. Therefore, confirming that patients are responding to these therapies is extremely important. Currently, follow-up is performed using radiographic evaluation, which has its limitations. Liquid biopsies, reflecting real-time tumor characteristics, hold great potential in monitoring tumor disease. PATIENTS AND METHODS: Blood samples were collected at different time points during treatment of 24 mCRC patients...
June 2018: Clinical Colorectal Cancer
Han Wu, Xinlian Chen, Xinghua Gao, Mengying Zhang, Jinbo Wu, Weijia Wen
High-throughput measurements can be achieved using droplet-based assays. In this study, we exploited the principles of wetting behavior and capillarity to guide liquids sliding along a solid surface with hybrid wettability. Oil-covered droplet arrays with uniformly sized and regularly shaped picoliter droplets were successfully generated on hydrophilic-in-hydrophobic patterned substrates. More than ten thousand 31-pL droplets were generated in 5 s without any sophisticated instruments. Covering the droplet arrays with oil during generation not only isolated the droplets from each other but also effectively prevented droplet evaporation...
April 3, 2018: Analytical Chemistry
Eugen Kaganovitch, Xenia Steurer, Deniz Dogan, Christopher Probst, Wolfgang Wiechert, Dietrich Kohlheyer
Microfluidics has enabled various research projects in the field of microbial single-cell analysis. In particular, single-use microfluidic cultivation devices combined with automated time-lapse imaging provide powerful approaches for analyzing microbial phenomena at the single-cell level. High spatiotemporal resolution facilitates individual cell identification and tracking, delivering detailed insights into areas like phenotypic population heterogeneity, which can be highly relevant to the fate of a microbial population and may negatively impact the efficiency of biotechnological fermentations...
March 14, 2018: New Biotechnology
Srujan Kumar Dondapati, Doreen A Wüstenhagen, Eckhard Strauch, Stefan Kubick
The pore forming characteristic of TDH1 and TDH2 variants of thermostable direct hemolysin (TDH), a major toxin involved in the pathogenesis of Vibrio parahaemolyticus , was studied on a planar lipid bilayer painted over individual picoliter cavities containing microelectrodes assembled in a multiarray. Both proteins formed pores upon insertion into the lipid bilayer which was shown as a shift in the conductance from the baseline current. TDH2 protein was able to produce stable currents and the currents were influenced by external factors like concentration, type of salt and voltage...
February 2018: Engineering in Life Sciences
Rogier M Schoeman, Wesley T E van den Beld, Evelien W M Kemna, Floor Wolbers, Jan C T Eijkel, Albert van den Berg
We present a microfluidic chip that enables electrofusion of cells in microdroplets, with exchange of nuclear components. It is shown, to our knowledge for the first time, electrofusion of two HL60 cells, inside a microdroplet. This is the crucial intermediate step for controlled hybridoma formation where a B cell is electrofused with a myeloma cell. We use a microfluidic device consisting of a microchannel structure in PDMS bonded to a glass substrate through which droplets with two differently stained HL60 cells are transported...
February 27, 2018: Scientific Reports
Barrett K Duan, Peter E Cavanagh, Xiang Li, David R Walt
This report describes a novel method for isolating and detecting individual enzyme molecules using polymer arrays of picoliter microwells. A fluidic flow-cell device containing an array of microwells is fabricated in cyclic olefin polymer (COP). The use of COP microwell arrays simplifies experiments by eliminating extensive device preparation and surface functionalization that are common in other microwell array formats. Using a simple and robust loading method to introduce the reaction solution, individual enzyme molecules are trapped in picoliter microwells and subsequently isolated and sealed by fluorinated oil...
March 6, 2018: Analytical Chemistry
Jian-Zhang Pan, Pan Fang, Xiao-Xia Fang, Ting-Ting Hu, Jin Fang, Qun Fang
In this work, we developed a miniaturized palmtop high-speed capillary electrophoresis (CE) system integrating whole modules, including picoliter-scale sample injection, short capillary-based fast CE, high-voltage power supply, orthogonal laser induced fluorescence (LIF) detection, battery, system control, on-line data acquisition, processing, storage, and display modules. A strategy of minimalist miniaturization combining minimal system design and low-cost system construction was adopted to achieve the instrument miniaturization with extremely low cost, which is differing from the current microfabrication strategy used in most reported miniaturized CE systems...
January 29, 2018: Scientific Reports
Armend G Håti, Tomasz R Szymborski, Mathias Steinacher, Esther Amstad
Drops are often used as picoliter-sized reaction vessels, for example for high-throughput screening assays, or as templates to produce particles of controlled sizes and compositions. Many of these applications require close control over the size of drops, which can be achieved if they are produced with microfluidics. However, this tight size control comes at the expense of the throughput that is too low for many materials science and almost all industrial applications. To overcome this limitation, different parallelized microfluidic devices have been reported...
February 13, 2018: Lab on a Chip
A Ganguli, A Ornob, N Spegazzini, Y Liu, G Damhorst, T Ghonge, B Thornton, C J Konopka, W Dobrucki, S E Clare, R Bhargava, A M Smith, F Kosari, R Bashir
Here, we present a technique that performs on-chip picoliter real-time reverse transcriptase loop mediated isothermal amplification (RT-LAMP) reactions on a histological tissue section without any analyte purification while preserving the native spatial location of the nucleic acid molecules. We demonstrate this method by amplifying TOP2A messenger RNA (mRNA) in a prostate cancer xenograft with 100 µm spatial resolution and by visualizing the variation in threshold time of amplification across the tissue...
January 15, 2018: Nature Communications
Jinyu Chen, Zhaofeng Luo, Lin Li, Jinlong He, Luoquan Li, Jianwei Zhu, Ping Wu, Liqun He
The droplet digital polymerase chain reaction (ddPCR) is becoming more and more popular in diagnostic applications in academia and industry. In commercially available ddPCR systems, after they have been made by a generator, the droplets have to be transferred manually to modules for amplification and detection. In practice, some of the droplets (∼10%) are lost during manual transfer, leading to underestimation of the targets. In addition, the droplets are also at risk of cross-contamination during transfer...
January 30, 2018: Lab on a Chip
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