Dry Spinning of Nucleotide-Based Fibers Comprising the Ion Complex between Biomass DNA and Cationic Lipid

DNA is considered a polyanion with high molecular weight comprising a nucleotide and phosphate. Thus, it is a candidate for biobased functional fibers. However, nucleotide-based fiber production on a bulk scale has not yet been realized. A large amount of DNA can be extracted from food waste, such as fish milts. Herein, we used DNA extracted from salmon milt waste and produced biomass DNA-based fibers by dry spinning using a DNA-cationic lipid complex as a dope solution. Producing fibers solely comprising DNA was difficult because electrostatic repulsions between phosphate anions prevented the packing of DNA molecular chains. Thus, we used ion complexes between DNA and cationic lipids to reduce electrostatic repulsions, enabling continuous spinning. The mechanical properties of the obtained fibers were maintained regardless of the drawing extension degree during the spinning process. The fibers had a lamellar structure formed by repeating a single-stranded DNA layer that interacted with the lipid bilayers in the dry state. By contrast, the fibers exhibited a double-stranded DNA layer and an interdigitated lipid bilayer in the humid state. Irrespective of the drawing extension and humidity conditions, the DNA molecules in the fibers remained randomly oriented.