Controlled Release of Microorganisms from Engineered Living Materials

Area of Science:

• Biomaterials Science
• Microbiology
• Synthetic Biology

Background:

• Probiotics modulate the microbiome and immune response for therapeutic benefits.
• Effective probiotic therapy requires sustained persistence at the target site.
• Existing methods lack biomaterials for sustained, clinically relevant probiotic release.

Purpose of the Study:

• To develop a novel biomaterial for sustained release of metabolically active probiotics.
• To establish a generic mechanism for controlled microbial delivery using engineered living materials.
• To demonstrate zero-order release kinetics for probiotic delivery.

Main Methods:

• Encapsulating stiff probiotic microorganisms within less stiff hydrogels.
• Utilizing microbial proliferation to induce hydrogel fracture and subsequent release.
• Characterizing release kinetics and dose-response by varying initial cell loading and matrix properties.
• Testing controlled release across diverse microbial types (Gram-negative, Gram-positive, fungal).

Main Results:

• Engineered living materials (ELMs) release >10^8 colony-forming-units (CFUs) of Escherichia coli within 2 hours.
• Sustained probiotic release was observed for at least 100 days.
• Release kinetics followed zero-order release, indicating a constant rate of delivery.
• Microbial release was controllable over three orders of magnitude by adjusting loading and matrix mechanics.
• Demonstrated controlled release of various probiotic types from multiple hydrogel matrices.

Conclusions:

• A novel hydrogel fracture mechanism enables sustained and controlled release of probiotics.
• This engineered living material approach overcomes limitations in achieving probiotic persistence for therapeutic applications.
• The mechanical release mechanism offers a versatile platform for delivering diverse therapeutic microorganisms.