Improving the Tensile Properties of Wet Spun Silk Fibers Using Rapid Bayesian Algorithm

Abstract

Wet spinning of silkworm silk has the potential to overcome the limitations of the natural spinning process, producing fibers with exceptional mechanical properties. However, the complexity of the extraction and spinning processes have meant that this potential has so far not been realized. The choice of silk processing parameters, including fiber degumming, dissolving, and concentration, are critical in producing a sufficiently viscous dope, while avoiding silk’s natural tendency to gel via self-assembly. This study utilized recently developed rapid Bayesian optimization to explore the impact of these variables on dope viscosity. By following the dope preparation conditions recommended by the algorithm, a 13% (w/v) silk dope was produced with a viscosity of 0.46 Pa·s, approximately five times higher than the dope obtained using traditional experimental design. The tensile strength, modulus, and toughness of fibers spun from this dope also improved by a factor of 2.20×, 2.16×, and 2.75×, respectively. These results represent the outcome of just five sets of experimental trials focusing on just dope preparation. Given the number of parameters in the spinning and post spinning processes, the use of Bayesian optimization represents an exciting opportunity to explore the multivariate wet spinning process to unlock the potential to produce wet spun fibers with truly exceptional mechanical properties.

Spinning Beta Silks Requires Both pH Activation and Extensional Stress

“…In addition, such efforts are yet to include a quantitative discussion of process energy efficiency, a topic becoming increasingly important from both an industrial and consumer perspective. [ 4,5 ]…”

Toughening Wet‐Spun Silk Fibers by Silk Nanofiber Templating

“…Therefore, aqueous silk fibroin solutions were also prepared from the same B. mori silk source to ensure optimal interactions upon mixing with SN. We used our previously developed dissolution protocol [ 33 ] to produce silk fibroin of different chain lengths (i.e., 33 and 184 kDa, as determined using size exclusion HPLC [ 22 ] ). After several iterations of silk dope preparation, we found that the SN must first be dispersed using 33 kDa silk fibroin prior to its addition to a 184 kDa silk fibroin solution ( Figure C).…”

“…A detailed description of how these preparation conditions produce silk with these molecular weights can be found in the previous work. [ 33 ]…”

“…This enhanced structural organization in an aqueous spun all-silk pseudocomposite fiber A detailed description of how these preparation conditions produce silk with these molecular weights can be found in the previous work. [33] offers a potentially scalable strategy to unlock the remarkable mechanical properties of regenerated silk fibers derived from the hierarchical nature of their fibrils.…”

“…A) Representative SEM image of exfoliated silk nanofiber; B) homogenous suspensions made by mixing SN in LMW silk solution and then mixing the stabilized dispersion with HMW silk solution. Labels indicate the solid content (wt%) of SN in the suspension; C) Schematic flowchart of the SN-x silk dope preparation where aqueous silk nanofiber dispersion is initially mixed with 33 kDa silk fibroin solution, and then subsequently mixed with 184 kDa silk fibroin solution.A detailed description of how these preparation conditions produce silk with these molecular weights can be found in the previous work [33].…”