Cells are cultured atop a polycarbonate membrane perforated in spots by vertical aluminum oxide nanostraws. At defined locations, where the membrane has been etched away lithographically, the nanostraws protrude from the membrane and contact the cells. A brief electric voltage is passed across the nanostraws, causing temporary perforations in the cell membrane. This allows small volumes of cytoplasm to diffuse into the nanostraws for collection in the reservoir of extraction buffer below the polycarbonate membrane.
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