3D Droplet Microfluidic Systems for High-Throughput Biological Experimentation

Kang, Dong-Ku,Gong, Xiuqing,Cho, Soongwon,Kim, Jin-young,Edel, Joshua B.,Chang, Soo-Ik,Choo, Jaebum,deMello, Andrew J. American Chemical Society 2015 ANALYTICAL CHEMISTRY - Vol.87 No.21

<P>Herein, we describe the development of a multilayer droplet microfluidic system for creating concentration gradients and generating microdroplets of varying composition for high-throughput biochemical and cell-based screening applications. The 3D droplet-based microfluidic device consists of multiple PDMS layers, which are used to generate logarithmic concentration gradient reagent profiles. Parallel flow focusing structures are used to form picoliter-sized droplets of defined volumes but of varying composition. As proof of concept, we demonstrate rapid enzymatic activity assays and drug cytotoxicity assays on bacteria. The 3D droplet-based microfluidic platform has the potential to allow for high-efficiency and high-throughput analysis, overcoming the structural limitations of single layer microfluidic systems.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2015/ancham.2015.87.issue-21/acs.analchem.5b02402/production/images/medium/ac-2015-02402t_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac5b02402'>ACS Electronic Supporting Info</A></P>

Interfacial Tension-Mediated Droplet Fusion in Rectangular Microchannels

홍종인,최민석,Joshua B. Edel,Andrew J. deMello 한국바이오칩학회 2009 BioChip Journal Vol.3 No.3

We successfully demonstrate the merging of aqueous droplets within a microfluidic channel mediated by a difference in interfacial tension. Interfacial tension is shown to have a significant influence on the hydrodynamic forces associated with a segmented flow in a rectangular microchannel and results in the possibility of merging multiple droplets in a simple fashion. This facility is important in allowing droplet-based microfluidic systems to be used as synthetic tools in complex reaction processing.

Droplet-Interfaced Microchip and Capillary Electrophoretic Separations

Niu, Xize,Pereira, Fiona,Edel, Joshua B.,de Mello, Andrew J. American Chemical Society 2013 ANALYTICAL CHEMISTRY - Vol.85 No.18

<P>Both capillary and chip-based electrophoresis are powerful separation methods widely used for the separation of complex analytical mixtures in the fields of genomics, proteomics, metabolomics, and cellular analysis. However their utility as basic tools in high-throughput analysis and multidimensional separations has been hampered by inefficient or biased sample injection methods. Herein, we address this problem through the development of a simple separation platform that incorporates droplet-based microfluidic module for the encapsulation of analytes prior to the analytical separation. This method allows for the precise and reproducible injection of pL to nL volume isolated plugs into an electrophoretic separation channel. The developed platform is free from inter sample contamination, allows for small sample size, high-throughput analysis, and can provide quantitative analytical information.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2013/ancham.2013.85.issue-18/ac401383y/production/images/medium/ac-2013-01383y_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac401383y'>ACS Electronic Supporting Info</A></P>

Design of a solid-state nanopore-based platform for single-molecule spectroscopy

Hong, Jongin,Lee, Yoonjae,Chansin, Guillaume A T,Edel, Joshua B,deMello, Andrew J IOP Pub 2008 Nanotechnology Vol.19 No.16

<P>We numerically assess the light propagation and distribution characteristics of electromagnetic fields on nanopores formed in dielectric and metal/dielectric membranes using a frequency-domain finite element method (3D full-wave electromagnetic field simulation). Results of such studies were used to identify aluminum as an ideal material for use in optically thick metal/dielectric membranes. The comparison between SiN and Al/SiN membranes (with and without a submicron sized aperture) was numerically and experimentally shown to verify the effect of optically thick metal layers on light propagation and fluorescence excitation. The cut-off behavior for Al/SiN membranes with varying pore diameters was investigated in terms of light propagation, distribution of electromagnetic fields, and light attenuation characteristics. </P>

Opportunities for microfluidic technologies in synthetic biology

Gulati, Shelly,Rouilly, Vincent,Niu, Xize,Chappell, James,Kitney, Richard I.,Edel, Joshua B.,Freemont, Paul S.,deMello, Andrew J. The Royal Society 2009 Journal of the Royal Society, Interface Vol.6 No.suppl4

<P>We introduce microfluidics technologies as a key foundational technology for synthetic biology experimentation. Recent advances in the field of microfluidics are reviewed and the potential of such a technological platform to support the rapid development of synthetic biology solutions is discussed.</P>

Analysis of Protein–Protein Interactions by Using Droplet-Based Microfluidics

Srisa-Art, Monpichar,Kang, Dong-Ku,Hong, Jongin,Park, Hyun,Leatherbarrow, Robin J.,Edel, Joshua B.,Chang, Soo-Ik,deMello, Andrew J. WILEY-VCH Verlag 2009 Chembiochem Vol.10 No.10

<P>Every little drop: The K<SUB>D</SUB> values of angiogenin (ANG) interactions as shown by FRET analysis of thousands of pL-sized droplets agree with data from bulk-fluorescence polarization measurements. Importantly, the use of fluorophores does not affect the activity of ANG or the binding of anti-ANG antibodies to ANG. Such an experimental platform could be applied to the high-throughput analysis of protein–protein interactions. <img src='wiley_img/14394227-2009-10-10-CBIC200800841-content.gif' alt='wiley_img/14394227-2009-10-10-CBIC200800841-content'> </P> <B>Graphic Abstract</B> <P>Every little drop: The K<SUB>D</SUB> values of angiogenin (ANG) interactions as shown by FRET analysis of thousands of pL-sized droplets agree with data from bulk-fluorescence polarization measurements. Importantly, the use of fluorophores does not affect the activity of ANG or the binding of anti-ANG antibodies to ANG. Such an experimental platform could be applied to the high-throughput analysis of protein–protein interactions. <img src='wiley_img/14394227-2009-10-10-CBIC200800841-content.gif' alt='wiley_img/14394227-2009-10-10-CBIC200800841-content'> </P>

Droplet-Based Microfluidic Platform for High-Throughput, Multi-Parameter Screening of Photosensitizer Activity

Cho, Soongwon,Kang, Dong-Ku,Sim, Steven,Geier, Florian,Kim, Jin-Young,Niu, Xize,Edel, Joshua B.,Chang, Soo-Ik,Wootton, Robert C. R.,Elvira, Katherine S.,deMello, Andrew J. American Chemical Society 2013 ANALYTICAL CHEMISTRY - Vol.85 No.18

<P>We present a fully integrated droplet-based microfluidic platform for the high-throughput assessment of photodynamic therapy photosensitizer (PDT) efficacy on <I>Escherichia coli</I>. The described platform is able to controllably encapsulate cells and photosensitizer within pL-volume droplets, incubate the droplets over the course of several days, add predetermined concentrations of viability assay agents, expose droplets to varying doses of electromagnetic radiation, and detect both live and dead cells online to score cell viability. The viability of cells after encapsulation and incubation is assessed in a direct fashion, and the viability scoring method is compared to model live/dead systems for calibration. Final results are validated against conventional colony forming unit assays. In addition, we show that the platform can be used to perform concurrent measurements of light and dark toxicity of the PDT agents and that the platform allows simultaneous measurement of experimental parameters that include dark toxicity, photosensitizer concentration, light dose, and oxygenation levels for the development and testing of PDT agents.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2013/ancham.2013.85.issue-18/ac4022067/production/images/medium/ac-2013-022067_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac4022067'>ACS Electronic Supporting Info</A></P>

Synchronized Optical and Electronic Detection of Biomolecules Using a Low Noise Nanopore Platform

Pitchford, William H.,Kim, Hyung-Jun,Ivanov, Aleksandar P.,Kim, Hyun-Mi,Yu, Jae-Seok,Leatherbarrow, Robin J.,Albrecht, Tim,Kim, Ki-Bum,Edel, Joshua B. American Chemical Society 2015 ACS NANO Vol.9 No.2

<P>In the past two decades there has been a tremendous amount of research into the use of nanopores as single molecule sensors, which has been inspired by the Coulter counter and molecular transport across biological pores. Recently, the desire to increase structural resolution and analytical throughput has led to the integration of additional detection methods such as fluorescence spectroscopy. For structural information to be probed electronically high bandwidth measurements are crucial due to the high translocation velocity of molecules. The most commonly used solid-state nanopore sensors consist of a silicon nitride membrane and bulk silicon substrate. Unfortunately, the photoinduced noise associated with illumination of these platforms limits their applicability to high-bandwidth, high-laser-power synchronized optical and electronic measurements. Here we present a unique low-noise nanopore platform, composed of a predominately Pyrex substrate and silicon nitride membrane, for synchronized optical and electronic detection of biomolecules. Proof of principle experiments are conducted showing that the Pyrex substrates have substantially lowers ionic current noise arising from both laser illumination and platform capacitance. Furthermore, using confocal microscopy and a partially metallic pore we demonstrate high signal-to-noise synchronized optical and electronic detection of dsDNA.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-2/nn506572r/production/images/medium/nn-2014-06572r_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn506572r'>ACS Electronic Supporting Info</A></P>

Rapid Ultrasensitive Single Particle Surface-Enhanced Raman Spectroscopy Using Metallic Nanopores

Cecchini, Michael P.,Wiener, Aeneas,Turek, Vladimir A.,Chon, Hyangh,Lee, Sangyeop,Ivanov, Aleksandar P.,McComb, David W.,Choo, Jaebum,Albrecht, Tim,Maier, Stefan A.,Edel, Joshua B. American Chemical Society 2013 NANO LETTERS Vol.13 No.10

<P>Nanopore sensors embedded within thin dielectric membranes have been gaining significant interest due to their single molecule sensitivity and compatibility of detecting a large range of analytes, from DNA and proteins, to small molecules and particles. Building on this concept we utilize a metallic Au solid-state membrane to translocate and rapidly detect single Au nanoparticles (NPs) functionalized with 589 dye molecules using surface-enhanced resonance Raman spectroscopy (SERRS). We show that, due to the plasmonic coupling between the Au metallic nanopore surface and the NP, signal intensities are enhanced when probing analyte molecules bound to the NP surface. Although not single molecule, this nanopore sensing scheme benefits from the ability of SERRS to provide rich vibrational information on the analyte, improving on current nanopore-based electrical and optical detection techniques. We show that the full vibrational spectrum of the analyte can be detected with ultrahigh spectral sensitivity and a rapid temporal resolution of 880 μs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-10/nl402108g/production/images/medium/nl-2013-02108g_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl402108g'>ACS Electronic Supporting Info</A></P>