Lichtgedanken 05

S C HW E R P U N K T 25 05 | LICHT GEDANKEN Nanomaterials have been in use for a long time now. Why do we need new nanoparticles? You can certainly argue that »nano« is »old hat« in pharmacy: titanium oxi- de nanoparticles can be found in sun creams, while silicon dioxide is used in cosmetics and in matrix tablets. One new aspect and the thing that is cur- rently being intensively researched is nanomaterials that can be used as transporters for active substances, so they can be better dosed or transported through biological barriers to their spe- cific destination. How does it work? By packaging active substances in nanoparticles, toxic, unstable or poorly soluble substances can be introduced into the organism. On the other hand, nanoparticles can be given a target con- trol that directs them to the desired cells or tissues. The packaging prevents toxic substances, such as chemotherapeutic agents, from damaging healthy tissue and from causing side effects. The lat- ter works already very well in the cell model but often only to a limited extent in humans. Why is that? I think it is simply because we don’t know enough about it. We need a va- lid taxonomy to show which polymers, with which chain length, are best-suited to which applications. We need to syste- matically record how shape, size, charge and the ligands of the particles deter- mine their properties. It would then be possible to develop a kind of modular system, from which the optimum par- ticle could be created depending on the application. This is what we are current- ly working on as part of the »Polytar- get« collaborative research centre. When it comes to the specific targeting of nanoparticles in humans—in other words the targeted transportation to the target tissue and the overcoming of biological barriers—that is still a gre- at challenge. Presumably because the human body is a very complex system. For example, we see that nanoparticles can be modified by the body as soon as they are introduced into the blood- stream. They are covered with a thick layer of proteins, which can comple- tely change the properties of particles. Blood flow and the blood vessels also play a role: the human body is a really large organism and nanoparticles have to overcome extreme distances—in re- lation to their size—and do so under flow conditions—a lot can go wrong en route. How can we overcome these challenges? The only way is by doing more basic research and creating better models. Observing the effects of nano-active substances in cell culture models is just Barrier-free access to the target tissue Not all nanos are the same. In this interview, Prof. Dr Dagmar Fischer discusses which nanomaterials are best-suited to reaching their destination in the organism, how the par- ticles behave once in the body’s bloodstream and why it has been so hard to use them in the human organism to date. Dagmar Fischer holds the Professorship for Pharmaceutical Technology and Biopharmacy. Her research interests include the development and application of nanoparticles that can release substances in a controlled manner. INTERVIEW: UTE SCHÖNFELDER F E AT U R E