Advances in Biological Liquid Crystals

Biological Liquid Crystal, a rich set of soft materials with rod-like structures widely existed in nature, possess typical lyotropic liquid crystalline phase properties both in vitro (e.g. cellulose, peptides and protein assemblies), and in vivo (e.g. cellular lipid membrane, packed DNA in bacteria and aligned fibroblasts). Given the ability to undergo phase transition in response to various stimuli, numerous practices have been exercised to spatially arrange biological liquid crystals. In this mini-review, the fundamental understanding of interactions between rod-shaped biological building blocks and their orientational ordering across multiple length scales is addressed. Discussions are made with regard to the dependence of physical properties of non-motile objects on the first-order phase transition and the coexistence of multi-phases in passive liquid crystalline systems. This review also focuses on how the applied physical stimuli drives the reorganization of constituent passive particles for a new steady-state alignment. A number of recent progresses in the dynamics behaviours of active liquid crystals are presented, and particular attention has been given to those self-propelled animate elements, like the formation of motile topological defects, active turbulence, correlation of orientational ordering and cellular functions. Finally, future implications and potential applications of the biological liquid crystalline materials are discussed.