Genetic Control of Radical Cross-linking in a Semisynthetic Hydrogel

Area of Science:

• Biomaterials Engineering
• Synthetic Biology
• Microbiology

Background:

• Designing next-generation technologies requires materials with living system qualities like sensing and adaptation.
• Living materials incorporate live cells to control material function, necessitating new methods to couple biological processes with material properties.

Purpose of the Study:

• To demonstrate how extracellular electron transfer (EET) from Shewanella oneidensis can control radical cross-linking in hyaluronic acid hydrogels.
• To establish a foundation for programming synthetic materials using genetic control over EET.

Main Methods:

• Leveraging extracellular electron transfer (EET) from Shewanella oneidensis to control radical cross-linking of methacrylate-functionalized hyaluronic acid hydrogels.
• Investigating the impact of bacterial genotype on cross-linking rates and hydrogel mechanics (storage modulus).
• Utilizing an inducible gene circuit for transcriptional control of material properties via MtrC expression.

Main Results:

• Cross-linking rates and hydrogel mechanics were dependent on bacterial genotype and other factors.
• Bacteria remained viable and metabolically active in hydrogels for over a week.
• EET genes controlled hydrogel microstructure, and MtrC expression transcriptionally regulated storage modulus and cross-linking rate.

Conclusions:

• A general mechanism for radical cross-linking was established, enabling genetic control over material properties via EET.
• This work provides a foundation for programming synthetic materials with tunable form and function through biological control.