Recombinant Silk Fiber Properties Correlate to Prefibrillar Self-Assembly

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Engineering

Background:

• Spider silks offer superior mechanical properties, biodegradability, and biocompatibility compared to synthetic materials.
• Replicating natural spider silk properties using recombinant spidroins and wet-spinning requires optimizing protein sequence, size, and spinning conditions.

Purpose of the Study:

• To investigate the effect of different solvent systems on the mechanical properties of recombinant spider silk fibers.
• To explore the relationship between dope-state protein structuring and the resulting fiber morphology, structure, and mechanical performance.

Main Methods:

• Utilized a consistent wet-spinning protocol with a ≈57 kDa recombinant aciniform silk protein.
• Dissolved the protein in two distinct fluorinated solvent systems to create different "spinning dope" solutions.
• Analyzed and compared the morphology, structure, and mechanical properties of the resulting silk fibers.

Main Results:

• Fibers produced from a fluorinated acid/alcohol/water dope exhibited significantly improved extensibility and toughness compared to those from a fluorinated alcohol/water dope.
• Distinct classes of spidroin nanoparticles were observed to form in the different dope solutions prior to spinning.
• The observed differences in dope-state protein assembly directly correlated with variations in fiber morphology, structure, and mechanical properties.

Conclusions:

• The choice of solvent for dissolving recombinant spider silk proteins is a critical factor in determining final fiber mechanical properties.
• Tailoring the assembly of dope-state spidroin nanoparticles presents a novel and promising strategy for modulating the performance of engineered spider silk materials.