Scientists have just revealed a surprising way to use coffee

A common drink in our homes has proven to be an effective, non-toxic substitute for the dangerous chemicals traditionally used in high-resolution microscopic imaging: coffee.

A new study shows that the espresso vulgaris can stain biological samples to electron microscopy with clarity and detail comparable to industry-standard radioactive solutions.

The discovery was presented in a recently published in the journal Methods.

To understand the magnitude of this discovery, it is necessary to first understand the invisible challenges of electron microscopy, explains .

Biologists rely on transmission electron microscopes, or TEMto visualize the internal structures of cells at nanometric scale. While optical microscopes use photons to illuminate an object, TEMs use beams of accelerated electrons.

This difference in the lighting source allows much higher magnification. However, it presents a fundamental problem for biological observation. Living beings are mainly composed of light chemical elements such as carbon, hydrogen, oxygen and nitrogen.

These light elements do not interact strongly with electron beams. When an electron beam passes through a slice of biological tissue, the electrons pass through it without being diverted or dispersed.

The result is a image with virtually no contrastmaking the cell’s intricate machinery invisible to the observer.

For decades, the solution has been impregnate the fabric with heavy metals. This process is known as positive staining. Heavy metal ions bind to cellular structures such as membranes or proteins.

When the electron beam hits these metal-coated areas, the electrons are repelled, which creates dark areas in the final imagewhile unstained areas remain clear. THE resulting contrast allows researchers to map the geography of the cell.

The current “standard of excellence” for this process is a chemical called uranyl acetatea salt derived from uranium exceptionally effective in binding biological lipids and proteins, which provides a sharp definition to cell membranes and DNA.

However, uranyl acetate presents serious disadvantages. It is highly toxic to the kidneys and chemically radioactive. Using such a dangerous material requires rigorous safety protocols, expensive waste disposal, and complex regulatory documentation, and some laboratories are even completely prohibited from owning it.

Consequently, the scientific community has been searching for a “green” alternative that is safe, cheap and effective. This search led a team of researchers in Austria to the kitchen break room.

Claudia Mayrhoferan ultramicrotomy expert at the Graz Electron Microscopy Center, led the research, in collaboration with colleagues from the Graz University of Technology and the University of Innsbruck.

Its work focuses on physical sample preparationwhich involves cutting tissue into slices thinner than a wavelength of visible light.

A inspiration for the study came from a banal observation. Mayrhofer noticed that coffee left in a cup for too long created persistent rings difficult to clean. He hypothesized that the compounds responsible for these stubborn stains could also effectively connect to biological tissues.

“I had the idea of ​​using espresso as coloring agent from the dried circular stains on used coffee cups,” said Mayrhofer. “Initial tests have shown that coffee stains biological samples and improves contrasts.”

To test this hypothesis rigorously, the team designed a comparative study. They needed to see How the coffee compared to the radioactive standard of uranyl acetate. They also compared it with other potential substitutes found in the literature.

The researchers selected the zebrafish as a biological objectand specifically focused on mitochondria within fish cells. Mitochondria are ideal for this type of test because they have complex double-layer membranes.

If staining is effective, these membranes appear as sharp lines and distinct. If the staining is poor, the membranes appear diffuse or blend in with the background. The team prepared a strong espresso solution using Robusta coffee.

They also tested a pure chlorogenic acid solution. This acid is a primary chemical component of coffee. Investigators suspected it could be the active ingredient responsible for the coloring effect.

The visual results were immediate and impressive. Samples treated with the espresso solution produced high quality images. Mitochondrial membranes were clearly visible and well defined.

When analyzed with an objective computer program, the coffee coloring had a admirable performance. Mayrhofer noted the success of the domestic drink in the press release. “Espresso provided comparatively very good contrast values, in some cases they were even better than with uranyl acetate”, he explained.

The study revealed that coffee coloring produced a contrast that allowed a easy differentiation of cellular structures. It was not merely an acceptable substitute, but a competitive alternative.

Pure chlorogenic acid also performed well, confirming that it plays an important role in the bonding process.

Researchers also tried using an Oolong tea extract. This had been suggested in previous scientific literature as a potential coloration. However, in this particular comparison, tea extract failed to produce sharp, artifact-free images.

The implications of these findings are economic as well as practical. Uranyl acetate is expensive to purchase and expensive to dispose of safely. Coffee is available in virtually all grocery stores at a fraction of the cost.

Furthermore, coffee does not pose any risk to health of the scientists who handle it. Does not require special ventilation, radiation shielding or government permits. Considerably simplifies the laboratory workflow.

There are, of course, reservations to this investigation. The study focused specifically on zebrafish mitochondria. Biological tissues vary greatly in their chemical composition.

Despite the need for more trials, the study represents a shift in the way scientists approach sample preparation. It suggests that the answer to complex laboratory problems may not always lie in synthesized chemicals. Sometimes, the solution is being prepared in the coffee maker next to.