4 research outputs found
Fast Nanoliter-Scale Cell Assays Using Droplet MicroarrayâMass Spectrometry Imaging
In pharmaceutical research and development, cellâbased assays are primarily used with readout that rely on fluorescenceâbased and other labelâdependent techniques for analysis of different cellular processes. Superhydrophobicâhydrophilic droplet microarrays (DMA) and matrixâassisted laser desorption/ionization (MALDI) mass spectrometry (MS) have recently emerged as key technologies for miniaturized highâthroughput cell assays and for labelâfree molecular highâcontent drug profiling, respectively. Here, nanoliterâscale cell assays are integrated on DMAs with MALDIâMS imaging (MALDIâMSI) approaches to a droplet microarrayâmass spectrometry imaging (DMAâMSI) platform. Using A549 lung cancer cells, concentrationâresponse profiling of a pharmaceutical compound, the fatty acid synthase inhibitor GSK2194069, are demonstrated. Direct cell culture on DMAs enables combination of microscopy and high speed, high molecular content analysis using MALDIâMSI. Miniaturization of array spots down to 0.5 mm confining 40 nL droplets allows for MALDI imaging analysis of as few as ten cells per spot. Partial automation ensures a fast sample preparation workflow. Taken together, the integrated DMAâMSI platform that combines MALDIâMSI, as a labelâfree analytical readout, with the miniaturized droplet microarray platform is a valuable complement to high throughput cellâbased assays technologies
Droplet Sorting and Manipulation on Patterned Two-Phase Slippery Lubricant-Infused Surface
Slippery lubricant-infused surfaces
are composite materials consisting
of a solid matrix permanently infused by a lubricant. Such surfaces
have proved to be highly repellent to various liquids immiscible with
the lubricant. Depending on the underlying surface chemistry, different
lubricants can be used, including perfluorinated or alkylated oils.
Here, we construct patterned slippery surfaces that consist of virtual
channels permanently impregnated with an organic oil and surrounded
by areas permanently impregnated with a perfluorinated oil. We demonstrate
that water droplets preferentially occupy the organic-oil-lubricated
virtual channels. Based on a simple model, we evaluate the forces
acting on droplets crossing over to the regions impregnated with perfluorinated
oil and show that the cloaking of the droplets plays an important
role. We study the actuation of droplets in virtual oil-in-oil channels
based on gravity and magnetic fields. Finally, we construct a variety
of organic-oil-lubricated channel architectures permitting droplet
sorting according to size. We believe that this novel approach for
the formation of virtual all-liquid surface-tension-confined channels
based on lubricant-infused surfaces, channel networks, or patterns
will advance the field of droplet-based microfluidics. The approach
presented can be potentially useful for applications in biotechnology,
diagnostics, or analytical chemistry