Less animal testing thanks to Nanosensors

Press briefing / January 02, 2012

Scientists of Fraunhofer EMFT aim to reduce the amount of animal testing with the help of novel nanosensors.

© Fraunhofer EMFT
With the yellow signal the nanosensors show that the cells are active. If they were in bad shape, they would be more red. Middle: Signal of the indicator substance. Left: Signal of the reference substance.

Countless mice, rats and rabbits die every year for the sake of science – and the number is rising. German labs tested approximately 2,41 million animals in 2005 for scientific research, in 2009 the number had already risen to 2,79 million. One third served biological basic research, the most needed for learning more about diseases and for developing medical products and equipment. People are demanding secure medicine and well-tolerated therapy, but nobody is prepared to accept animal testing. That is why scientists have been looking for alternative methods already for years. One alternative has been discovered by the scientists at Fraunhofer EMFT in Munich. They aim to reduce the amount of animal testing with the help of novel nanosensors. “We are testing the efficiency and potential risks of chemicals practically in test tubes. The method involves exposing living cells isolated from human and animal tissue to the substance under research,” Dr. Jennifer Schmidt from EMFT explains. If the substance is toxic for the cell in certain concentration, the cell dies. This change in “well-being” can be made visible using the sensor nano particles developed by Dr. Schmidt and her team.

Healthy cells store their energy as adenosine triphosphate (ATP). More ATP means more activity in this smallest living unit. If it is damaged, it reduces its metabolism, stores less energy and produces thus less ATP in the end. “With our nanosensors we can detect the adenosine triphosphate and monitor the health status of the cells. This again makes conclusions possible concerning the harmful effects of the medicine or chemicals on the cell”, Dr. Schmidt says.

The nanoparticles are equipped with two fluorescent dyes, in order to be able to detect the ATP. The green indicator dye reacts with ATP, yielding change in fluorescence intensity, while the red reference dye does not change its fluorescence intensity. In the next step the researchers inject the particles into living cells and monitor them under the fluorescence microscope. The degree of luminescence of the particles varies depending on the amount of ATP – more yellow colour in the overlay image means morecell activity. More of the red colour means worse condition of the cell. “With this method it will be possible to test for example the effectiveness of chemotherapeuticals on cancer cells in the future. If the nanosensors detect low ATP concentration in the cells, this indicates that the new medicine hinders the growth of the tumour cells or even kills them”, Dr. Schmidt.continues. “The most promising medical substances can then be investigated further.”

The nanoparticles of the scientists at Fraunhofer EMFT meet high standards: they are not toxic to cells, easily pass through the cell membrane, and can be transported directly to where the substance to be tested shall be detected. Before this method can be put to practical use, though, it must be approved by the admission authorities. This long journey through the approval authorities does not stop the experts of Fraunhofer EMFT from developing the technology further and finding other applications for it. One example is detecting the quality of packed meat and indicating if it is still edible. For this aim they have developed nanosensors, which are capable of determining the concentration of oxygen and toxic amines.