Measuring procedure to understand magnetic nanoparticles developed

Washington, May 29 : Scientists at Physikalisch-Technische Bundesanstalt (PTB) have developed a novel measuring procedure that may aid in the detailed investigation of the behaviour of magnetic nanoparticles, used in cancer therapy.

These days, magnetic nanoparticles (with a size of some few to several hundred nanometres) act as a promising way in combating cancer by acting as a carrier for drugs. The nanoparticles are first loaded" with the drugs and then are released into the blood stream, where they move until they come under the influence of a targeting magnetic field which holds them on to the tumour - until the drug has released its active agent.

In addition to its pharmaceutical effect, they also have a physical action, i.e. an electromagnetic a.c. field heats up the accumulated particles so much that they destroy the tumour. Both therapeutic concepts have the advantage of largely avoiding undesired side effects on the healthy tissue.

In fact, these procedures have already been successfully been applied in the animal model and have already been tested partly on patients. However, one should know before application, if the particles tend to aggregate and thus having the probability to occlude blood vessels.

One can get information about this by magnetorelaxometry developed at the PTB. In this procedure, the particles are shortly magnetised by a strong magnetic field in order to measure their relaxation after the switch-off of the field by means of superconducting quantum interferometers, so-called "SQUIDs".

It is possible to conclude about aggregation behaviour in these media by analysing measurements of suspensions of nanoparticles in the serum or in whole blood. For instance, it could be shown in this way that certain nanoparticles in the blood serum form clusters with a diameter of up to 200 nm - a clear indication of aggregation, so that these nanoparticles do not appear to be suitable for therapy

Currently, the high technical effort linked with the use of helium-cooled magnetic field sensors hampers the way of using this method routinely in practice.

The procedure is currently being transferred to a simpler technology based on fluxgate magnetometers in a joint project with Braunschweig Technical University supported by the Ministry of Education and Research (BMBF).

The results of the first orders from customers have served, for example, to optimise the paint drying process in the automobile industry, the thermal design of furnaces as well as the monitoring of glass forming processes.

And now, one more measuring facility is being set up in the PTB which will allow emissivity measurements to be performed under vacuum conditions in an extended temperature and wavelength range - particularly for space applications.

ANI