Nanoparticles hitchhiking their way along strands of hair (Vol. 48 No. 1)

Corrugated hair surface

Massaging hair can help more quickly deliver nanoparticle-based treatment to the roots

In shampoo ads, hair always looks like a shiny, smooth surface. But for physicists peering into microscopes, the hair surface looks much more rugged, as it is made of saw-tooth, ratchet-like scales. In a new theoretical study published recently, the authors have demonstrated that massaging hair can help to apply drug treatment—encapsulated in nanoparticles trapped in the channels formed around individual hairs—to the hair roots. This is because the oscillatory movement of the massaging directs the way these particles are transported. This phenomenon was previously discovered in experiments on pork skin samples, which were conducted by Jürgen Lademann, dermatologist at the Charité clinic in Berlin, Germany, and his team. It is also relevant at the microscopic scale, in the transport on microtubules taking place in two directions between the cells within our bodies. By constrast, these findings could also help find ways of preventing harmful nanoparticles from being transported along hairs into the wrong places.

M. Radtke and R. R. Netz, Ratchet effect for two-dimensional nanoparticle motion in a corrugated oscillating channel, Eur. Phys. J. E 39, 116 (2016)