• Climate, Environment & Health
  • Materials


Karlsruhe exposure system for the deposition of nanoparticles on cell cultures.

Almost 500 years ago, the physician Paracelsus formulated a medical principle that is still valid today: "All things are poison, and nothing is without poison; the dose alone makes a thing not a poison.” Particulate matter has an impact on human health, which has led to legal limits. However, these particulate emission limits only refer to the particulate concentration, which alone does not provide any information about the toxic load. KIT scientists Dr. Hanns-Rudolf Paur and Sonja Mülhopt are developing systems that provide measurements that are more accurate.

"Before you can determine which dose has a toxic effect, you first have to figure out what the substance is," says Mülhopt, a process engineer. This is exactly what the current particulate matter measurements do not do. They merely weigh how much particulate matter arrives at the unit in a certain period. "However, the decisive factor is how large the individual particles are," says the scientist. This is because the properties of a substance often change above a certain size limit - what is harmless at macro size can be toxic at nano size. The smaller a particle, the deeper it can penetrate the body's lung system. While larger particles are trapped in the nasopharynx and quickly expelled, particles smaller than one micrometer are deposited in the alveoli of the lungs over a long period of time - a health risk that can lead to cardiovascular diseases and cancer. Motor traffic, industry and home fireplaces are the largest contributors to particulate matter in the air.

"For us, it's great to see the quintessence of our work flowing into industrial applications."

Hanns-Rudolf Paur


Back 12 years ago, Sonja Mülhopt and Dr. Hanns-Rudolf Paur began asking themselves how you could realistically test gas-borne ultra-fine particles. They reached the conclusion that "we have to create a device that maps the processes in the human body from the nose to the lungs and outputs reproducible results on size and substance," explains chemist Paur. A complex undertaking: Common test methods are not suitable for simulating the flow of an air stream through the lungs.

This is because the measuring chambers used for this purpose hold the human cells in a liquid nutrient solution, which can falsify test results. Moreover, you cannot easily handle an aerosol, gas-borne particles like those present in air streams, in a standardized device. "In our measurement chambers, the 'inhaled' particles do not hit a liquid, but directly hit the lung cells. Currently, we are developing the marketable overall system around these measurement chambers," says Sonja Mülhopt. A goal that the scientists are implementing together with KIT colleagues from the field of biology and the company VITROCELL Systems in the course of a technology transfer project.

After a first successful joint product development, a quartz microbalance for the determination of particle deposition, the partners have been working since October on the first generation of equipment that combines all modules and refines the measurements. In the long term, Paur and Mülhopt have an ambitious goal: "The tests should run completely automatically and our device should be used in every toxicology laboratory to evaluate the effect of particulate matter."

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Pictures: KIT


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