Researchers have discovered a safe, non-toxic alternative to the hazardous chemicals used in high-resolution microscopic imaging, publishing their findings in the journal Methods. The new study demonstrates that ordinary espresso coffee can effectively stain biological samples for electron microscopy with a clarity and detail rivaling industry-standard radioactive solutions.
For decades, scientists have relied on a process known as positive staining, which involves impregnating tissue with heavy metals so that their ions bind to cellular structures. This is necessary because the light chemical elements that compose living things do not interact strongly with electron beams in transmission electron microscopes (TEMs), resulting in images with almost no contrast. The discovery that a common household beverage can replace these toxic heavy metals represents a significant breakthrough for laboratory safety and accessibility.