Journal: Nature Communications

Article Title: Dielectrophoretic bead-droplet reactor for solid-phase synthesis

doi: 10.1038/s41467-024-49284-z

Figure Lengend Snippet: a In DBDR reactions are implemented by encapsulating and ejecting individual beads from reagent droplets. This is achieved by simply tuning the voltage supply on the trap electrode that modulates the balance between counteracting dielectrophoretic and capillary force. Inside the droplet, the fluorescently labeled nucleotides (dCTP-AF647) couple onto the initiator strands on the bead. b The device footprint depicts the alignment of the droplet generator and the electrodes in the reaction chamber and the spatial location of the bead and the dispensed droplet. The dashed box shows the section of the device in ( a ). c Fabricated silicon-on-glass microfluidic device with ITO electrodes. Purple color is overlayed on the transparent ITO electrodes to distinguish them from the device background. The strong electric field gradient of the electrodes enables dielectrophoretic trapping. The arrows indicate the direction of the electric field. d Representation of chemical reactions on the solid support: (i) Binding the initiator strand on the bead through streptavidin-biotin hydrogen bonds, (ii) Enzymatic coupling of fluorescently labeled nucleotides (dCTP-AF647) onto the 3′ end of the initiator strands on the bead inside the reagent droplet.

Article Snippet: The contact angles were measured by capturing the droplet shape on a streptavidin coated glass slide (GS-SV-5 from Nanocs) and silanized glass surface and then estimating the angle it forms on the surface through shape fitting.

Techniques: Labeling, Binding Assay

Journal: Nature Communications

Article Title: Dielectrophoretic bead-droplet reactor for solid-phase synthesis

doi: 10.1038/s41467-024-49284-z

Figure Lengend Snippet: a Larger droplet \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left({R}_{d}=50 \, \upmu {{\rm{m}}}\right)$$\end{document} R d = 50 μ m can encapsulate the bead at a much lesser supply voltage ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}_{s}\approx 85V$$\end{document} V s ≈ 85 V ). b Smaller droplet \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left({R}_{d}=20 \, \upmu {{\rm{m}}}\right)$$\end{document} R d = 20 μ m requires a larger supply voltage ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}_{s}\approx 135V$$\end{document} V s ≈ 135 V ) to overcome the capillary force and encapsulate the bead. At the lower voltage ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}_{s} \, \approx \, 117 \, {{\rm{V}}}$$\end{document} V s ≈ 117 V ) the dielectrophoretic force cannot overcome the capillary force to encapsulate the bead into the smaller droplet (It was enough to encapsulate the bead in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${R}_{d}=25 \, \upmu {{\rm{m}}}$$\end{document} R d = 25 μ m droplet). c The low viscosity of silicone oil 1 cSt enables the ejection of the bead from the droplet at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}_{s} \, \approx \, 0.1\, {{\rm{V}}}$$\end{document} V s ≈ 0.1 V . With increase in oil viscosity the increased dissipation of the kinetic energy of the droplet prevents complete separation from the bead. d Silicone oil 1 cSt (dashed line) renders the hydrophilic (in air, dotted line) streptavidin surface slightly hydrophobic. The surfactant Span80 further reduces the interfacial tension between the silicone oil and the reagent and increases the contact angle (solid line) that the reagent droplet forms on a streptavidin surface making it hydrophobic. It is critical for the ejection of the bead from the droplet. Interfacial tension and contact angle measurements are recorded with time variations to account for the surface adsorption. (Refer to Experimental Procedure for Bead-Droplet Interaction subsection of Methods for details.) The streptavidin and glass thicknesses are not drawn to scale. The scale bars on experimental frames in ( a , b ) represent \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$40 \, \upmu {{\rm{m}}}$$\end{document} 40 μ m . The symbol ϕ in the color plots is the phase variable in the phase field simulations. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\phi=-1$$\end{document} ϕ = − 1 in the oil medium (represented in blue) and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\phi=1$$\end{document} ϕ = 1 in the aqueous medium (represented in red). \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$-1 < \phi < 1$$\end{document} − 1 < ϕ < 1 represents the boundary region between the droplet and the oil medium.

Article Snippet: The contact angles were measured by capturing the droplet shape on a streptavidin coated glass slide (GS-SV-5 from Nanocs) and silanized glass surface and then estimating the angle it forms on the surface through shape fitting.

Techniques: Viscosity, Adsorption