
The yellow nanosensor signal in the overlay image (right) shows that the cells are active. If they were unhealthy, they would appear much redder. Center: the indicator dye signal. Left:... Countless mice, rats and rabbits die every year in the name of science – and the situation is getting worse. While German laboratories used some 2.41 million animals for scientific research in 2005, by 2009 this number had grown to 2.79 million. One third were destined for fundamental biology research, and the majority were used for researching diseases and developing medical compounds and devices. People demand medicines that are safe and therapies that are tolerable, but hardly anyone is happy to accept the need for animal testing. This is why scientists have spent years looking for methods that can replace them. Now researchers at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT in Munich have found an alternative: they hope to use novel nanosensors to reduce the number of experiments that are carried out on animals. "We're basically using a test tube to study the effects of chemicals and their potential risks. What we do is take living cells, which were isolated from human and animal tissue and grown in cell cultures, and expose them to the substance under investigation," explains Dr. Jennifer Schmidt of the EMFT. If a given concentration of the substance is poisonous to the cell, it will die. This change in "well-being" can be rendered visible by the sensor nanoparticles developed by Dr. Schmidt and her team.