Orientational fluctuations and bimodality in semiflexible nunchucks

Semiflexible nunchucks are block copolymers consisting of two rather stiff arms  linked together with a softer polymer segment. Recently, nunchucks consisting of DNA nanorods linked with a segment of dsDNA have been used as a tool to measure the bending stiffness of dsDNA (Fygenson et al., Nano Lett. 2020). The same geometry also appears in dsDNA with a hinge defect (e.g., a long lived bubble) or in end linked F-actin filaments. In this talk, we present a theoretical analysis of the conformational fluctuations of this system. In particular, we focus on the bimodality in the transverse fluctuations of the free end of a grafted nunchuck. We also consider a nunchuck under tension and show the emergence of bimodality in the elastic response as a function of the hinge position.