Professor Robijn Bruinsma
Department of Physics & Astronomy, UCLA

 

Chiral Biopolymers and Josephson-Junction Arrays

 

Chirality, or handedness, is a pronounced feature of key biological molecules such as amino acids and nucleic acids. Solutions of biopolymers such as DNA or filamentous Actin composed of chiral subunits clearly express their chirality at lower concentrations when they adopt the cholesteric liquid crystal phase. At higher concentrations however, biopolymers adopt the hexagonal bundle phase which seemingly has no clear chiral signature. The talk will discuss that the phase transition between the cholesteric and hexagonal phases can be mapped on the superconducting-to-insulating transition of a frustrated triangular 2-dimensional Josephson-Junction array in a magnetic field. Using this mapping, and known results of Josephson-Junction arrays, one can obtain the critical exponents of the transition and predict the presence of periodic arrays of chiral defects in biopolymer bundles.