Proc. Natl Acad. Sci. USA http://doi.org/trv (2014)

Credit: © 2014 PNAS

The protein elastin is best known for its mechanical properties: it's the reason our cheeks spring back into shape quickly after being pinched. But what of its electrical response? Yuanming Liu and colleagues have found macroscopic evidence of ferroelectric switching in elastin, and hit upon a model that recovers the polarization reversal underpinning this behaviour.

The same group previously reported an observation of ferroelectric switching in elastin and showed that it could be suppressed by glucose, but so far neither a macroscopic measurement nor a microscopic understanding of the underlying physics has been forthcoming. In the present study, Liu et al. used a combination of piezoresponse force microscopy measurements (pictured), molecular dynamics simulations and coarse-grained statistical mechanics to show that elastin retains its ferroelectric switching behaviour at high temperatures — its Curie temperature exceeding that of synthetic molecular ferroelectrics. This allowed them to probe the polarization of elastin on a macroscopic scale using pyroelectric current measurements.

The results of their simulation suggest that elastin polarization is strong even at the monomer level, much like the unit-cell polarization in perovskite ferroelectrics. And a structural model of elastin implicates the collective effect of aligned dipolar monomers in inducing the observed polarization.