Direct Correlation between Molecular Cross‐linking and Macroscopic Mechanical Properties for Green Solids of Deoxyribonucleic Acids

Abstract Double‐stranded deoxyribonucleic acids (DNAs) were intermolecularly cross‐linked using 2,5‐hexanedione under reductive amination conditions in aqueous phase. Cross‐linking points between DNAs were directly observed by atomic force microscopy in conjunction with a conventional gel electrophoresis analysis. While DNA chains near cross‐linking points were denatured, DNA chains not near cross‐linking points maintained B‐form double strands. A transparent and self‐supported film of cross‐linked DNA (DNA‐c) was obtained by a simple solvent‐casting method. The tensile properties of DNA‐c films were much better than those of non‐cross‐linked DNA (DNA‐n) films due to the presence of the cross‐linking portions. Structural analyses based on wide‐angle X‐ray diffraction measurements revealed that the reorientation of DNA‐c was remarkably restricted by the introduction of cross‐linking points.