Researchers have developed an alternative method to animal testing by using sensor nanoparticles that detect the level of cell activity.

Researchers are able to use test tubes to study the effects of chemicals and their potential risks by exposing culture-grown living cells isolated from human and animal tissue to substances under investigation, according to study author Jennifer Schmidt of the Fraunhofer Research Institution for Modular Solid State Technologies.

Researchers said in a released statement that healthier cells generate more energy in the form of adenosine triphospahe, due to higher levels of metabolic activity, and damaged cells become less active, store less energy and consequently produces less ATP. The newly developed nanosensors enabled researchers to assess the cell health with red and green indicator dyes.

“Our nanosensors allow us to detect adenosine triphosphate and determine the state of health of cells. This makes it possible to assess the cell-damaging effects of medical compounds or chemicals," said Schmidt.

Researchers color nanoparticles in red and green fluorescent dyes, the red is a reference dye that does not change color, and because the green indicator dye is sensitive to ATP it will change color depending on how much ATP is produced in the cell.

Healthier cells are shown to be more yellow, and sicklier cells will appear to be more red. 

"We could in future use cancer cells to test the effectiveness of newly developed chemotherapy agents. If the nanosensors detect a low concentration of ATP in the cells, we'll know that the new treatment is either inhibiting tumor cell growth or even killing them," said Schmidt. "The most promising agents could then be studied further."

Researchers said that nanoparticles are not poisonous to cells and can easily pass through cell membranes, and can even be maneuvered to particular points where the effect of the test substance is of most interest.

However, before researchers may only begin using the alternative method to animal testing after it is approved by various regulatory bodies.