This year, team [Squirrel-Beijing] is dedicated to revolutionizing postoperative care by transforming the surgical suture from a passive mechanical support into an active therapeutic device. Using synthetic biology, we have engineered E. coli to produce a multifunctional "living suture" that simultaneously provides structural integrity, prevents bacterial infection, and modulates inflammation. Our project, ReGenStitch, is built upon three core modules: a bacterial cellulose backbone, a surface-displayed chitinase for producing antimicrobial agents, and a curcumin synthesis pathway for anti-inflammatory effects. In total, we have contributed 4 new basic parts and 2 new composite parts to the registry, providing a comprehensive toolkit for engineering bioactive materials.

Basic Parts

• BBa_25AZ8G1G (bcsA, 2262 bp) – Encodes cellulose synthase catalytic subunit A, the core enzyme responsible for polymerizing glucose monomers into cellulose chains, forming the primary structure of our suture.
• BBa_257P28CR (chitinase, 2028 bp) – Encodes a chitinase capable of degrading chitin—a common biowaste—into chitooligosaccharides (COS), which possess potent antimicrobial properties.
• BBa_25YD5TM5 (INP-CHI1, 2565 bp, Gold Medal Part) – A key fusion protein part. It encodes the Ice Nucleation Protein (INP) fused to our chitinase (CHI1), anchoring the enzyme to the outer membrane of E. coli. This creates a recyclable whole-cell biocatalyst for efficient COS production.
• BBa_25FN7IQY (CURS1, 1170 bp) – Encodes Curcumin Synthase 1, a key enzyme that catalyzes the final condensation step in the biosynthesis of curcumin, a powerful anti-inflammatory compound.

Composite Parts

• BBa_259ZWYP3 (bcsA-bcsB) – A synthetic operon co-expressing the two essential subunits of cellulose synthase. This composite part is the engine for producing the bacterial cellulose backbone of the ReGenStitch suture, providing a robust and biocompatible scaffold for wound closure.
• BBa_25UM8LJ5 (DCS-CURS1, 2603 bp) – A composite part that constitutes the core of our anti-inflammatory module. It contains the genes for Diketide-CoA synthase (DCS) and Curcumin Synthase 1 (CURS1), enabling the de novo synthesis of curcumin from simple precursors.

Our work provides the iGEM community with a validated and modular set of tools for creating next-generation smart biomaterials and advancing the principles of a circular bioeconomy.

• A Modular Toolkit for Bioactive Material Synthesis: Our project is divided into three distinct functional modules (structural, antimicrobial, anti-inflammatory). Future teams can "mix and match" these parts. For example, the bcsA-bcsB operon (BBa_259ZWYP3) can be used to produce bacterial cellulose for any application, while the DCS-CURS1 part (BBa_25UM8LJ5) can be used to engineer any chassis to produce curcumin.
• A Validated Platform for Whole-Cell Biocatalysis: Our fusion part BBa_25YD5TM5 (INP-CHI1) provides a powerful, "plug-and-play" solution for surface-displaying enzymes. Future teams can easily adapt this by replacing the chitinase gene with their enzyme of interest, creating reusable biocatalysts for a wide range of applications without needing costly protein purification.
• A Blueprint for Biowaste Valorization: The chitinase module demonstrates a complete workflow for converting waste (chitin from shrimp shells) into a high-value product (antimicrobial COS). This serves as a practical guide for future teams interested in circular economy projects, tackling both pollution and sustainable manufacturing.
• New Functional Characterization for Existing Parts: We utilized and characterized several existing parts, such as BBa_K3520002 (bcsB), BBa_K523013 (INP), and BBa_K4986002 (DCS), within new composite devices. Our work provides critical functional data on how these parts perform in concert, enriching their utility for the iGEM community.

In summary, ReGenStitch is more than a single application; it is a demonstration of how modular design can be used to build complex, multifunctional living systems. We provide the synthetic biology community with valuable genetic parts, design principles, and a vision for the future of active therapeutic materials, fully embracing iGEM's spirit of "getting, giving, and sharing."