Topologically interlocked nano-coacervates surviving in harsh environment---revealing a new physical mechanism for biomolecular condensates

We have utilized dipolar mesomorphic state in a polylysine-acrylate sodium complexation as a template to induce in situ polymerization of acrylate along the polylysine chain by free radical polymerization. The size of the nano-coacervates made by templated polymerization increases with NaBr concentration and do not disassemble until 7.5M NaBr, while the mesomorphic state without polymerization will disassemble at 2M. Besides, such nano-coacervates can also resist low salt until 0.05M while for that without polymerization phase separation happens at 0.25M. The templated effect is weakened at higher salt concentration during polymerization, thus the nano-coacervates size decreases. We propose the nano-coacervates made by the in-situ templated polymerization have the topological interlock between polycations and newly formed polyacrylate with flower-like loop conformation. We also used trypsin enzyme to degrade the polylysine and break up the interlocked nano-coacervates, and we found the size of the newly formed daughter polyacrylate is similar to the templated mother polylysine. NMR results also demonstrate that the stronger the template effect, the higher the chemical monomer conversion, and the longer the daughter chains. Therefore, we have discovered a new class of nano-coacervate which can resist both high salt and low salt by topologically interlocks. Our discovery may reveal how the basic units were formed at the very beginning of our lives in the harsh ocean environment.