Continuous DNA Nanofibers with Extraordinary Mechanical Properties and High Molecular Orientation

The dual nano-macro nature of continuous nanofibers holds great promise in bridging the unique nanoscale properties of DNA to macroscopic devices. However, due to the limitations of existing manufacturing methods, controlled fabrication of macroscopically long DNA nanofibers has not been achieved so far. This article presents optimized electrospinning of substrate-free and uniform DNA nanofibers with macroscopic lengths and diameters ranging from ultrafine (<50 nm) to submicron scale. Mechanical tests of individual DNA nanofibers show highly nonlinear deformation in tension that is accompanied by unexpectedly high true strength (>1 GPa) and toughness (>200 MPa) values for the thinnest tested nanofibers. Molecular characterization with X-ray diffraction and polarized Raman spectroscopy indicates that the high mechanical properties and their unusual size effects in DNA nanofibers originate from the high molecular alignment that is preserved with the increase in diameter. These results show that electrospun DNA nanofibers can overcome the weaknesses of DNA nanostructures manufactured by other top-down and bottom-up methods and that they offer novel capabilities for the DNA-based nanomaterials.