In the medical field solid iron oxide nanoparticles can be selectively transported e.g. into tumor tissue in order to heat them from external alternating magnetic fields with the objective that only the tumor tissue will be damaged. Injections of iron oxide nanoparticles are not free of side effects though.
Fluid nanoparticles which are used in cosmetic products are completely free of side effects as they dissolve when they come in contact with the skin barrier and then completely fuse with the barrier layer. This increases the permeability of the skin barrier with the effect that encapsulated lipophilic agents can easier penetrate into the skin.
When discussing particle sizes it is important to point out that the smallest relevant particles are molecules which means that in dissolved form as for example in a watery solution the active agent has the smallest possible particle size that is to say a molecule. Compared to the cosmetic nanoparticle of 100 nm it is about 100 to 1000 times smaller.
For details please refer to our publication "Precious load - transport of active agents".
Dr. Hans Lautenschläger