A recombinant chimeric spider pyriform-aciniform silk with highly tunable mechanical performance.

Area of Science:

• Biomaterials Science
• Protein Engineering
• Textile Engineering

Background:

• Spider silks are natural protein-based biomaterials known for exceptional mechanical properties.
• Most spider silk types, such as pyriform and aciniform silks, remain understudied.
• Combining different silk types offers unexplored potential for novel material properties.

Purpose of the Study:

• To engineer a chimeric fusion protein (Py2W2) combining pyriform and aciniform silk units.
• To investigate the fiber formation and mechanical properties of the engineered Py2W2 silk.
• To explore the potential of Py2W2 as a tunable biomaterial for various applications.

Main Methods:

• Constructed a recombinant fusion protein (Py2W2) from pyriform (Py) and aciniform (W) silk units.
• Expressed and purified the Py2W2 protein using Escherichia coli.
• Utilized wet-spinning to form fibers, followed by post-spin stretching under various conditions (air, water, ethanol).

Main Results:

• The Py2W2 protein was successfully expressed and purified, forming high α-helicity dope for wet-spinning.
• Post-spin stretching increased molecular alignment and optical anisotropy in the fibers.
• Py2W2 fibers exhibited superior mechanical properties, including high extensibility (∼157%) and strength, surpassing constituent silks.
• The engineered silk demonstrated water compatibility and tunable secondary structures correlating with mechanical properties.

Conclusions:

• Engineered Py2W2 spider silk offers enhanced and tunable mechanical properties compared to natural silks.
• The study demonstrates a novel approach to creating advanced biomaterials by combining different spider silk types.
• Py2W2 provides a versatile platform for developing next-generation biomaterials for diverse applications.