Macromolecules can gain special properties by adopting knotted conformations, but engineering knotted macromolecules is a challenging task. Recently, a work appears in Science Advances [Science Advances 10, eadr0716 (2024)] report an anchored active polymer can spontaneously form knots, providing an efficient way to engineer the topology of macromolecules. More explicitly, the work finds that when one end of an actively reptative polymer is anchored, it undergoes continual self-knotting as a result of intermittent giant conformation fluctuations and the outward reptative motion. Once a knot is formed, it migrates to the anchoring point due to a non-equilibrium ratchet effect. Moreover, when the active polymer is grafted on a passive polymer, it can function as a self-propelling soft needle to either transfer its own knots or directly braid knots on the passive polymer. The authors further show that these active needles can create inter-molecular bridging knots between two passive polymers. This finding highlights the non-equilibrium effects in modifying the dynamic pathways of polymer systems, which have potential applications in macromolecular topology engineering. This work is from Prof. Yu-Qiang Ma group in school of physics in NJU.
Publication link:
Jia-Xiang Li, Song Wu, Li-Li Hao, Qun-Li Lei*, Yu-Qiang Ma*, Activity-driven polymer knotting for macromolecular topology engineering, Science Advances 10, eadr0716 (2024) https://www.science.org/doi/10.1126/sciadv.adr0716