Microencapsulation of High-Content Actives Using Biodegradable Silk Materials

Area of Science:

• Materials Science
• Biotechnology
• Chemical Engineering

Background:

• There is a growing demand for biodegradable alternatives to non-degradable microplastics across various industries.
• Challenges in controlled release and scalable manufacturing of new materials hinder the adoption of circular polymers for microplastic fabrication.

Purpose of the Study:

• To demonstrate active microencapsulation using silk fibroin, a structural protein.
• To enable the tunable manufacturing of microcapsules with controlled morphology and degradation kinetics.

Main Methods:

• Silk fibroin micelles' size was tuned by modulating protein protonation and chain relaxation.
• Spray drying and spray freeze drying techniques were retrofitted for microcapsule manufacturing.
• Beta-sheet content of silk fibroin was modulated to control degradation and payload release.

Main Results:

• Microcapsules with tunable morphology (hollow-spongy, hollow-smooth, hollow crumpled) were produced.
• Degradation kinetics and sustained release of soluble/insoluble payloads were controlled.
• Burst release of the herbicide saflufenacil decreased from 25% to 0.8% using silk fibroin microencapsulation.
• Greenhouse trials showed reduced crop injury with silk microcapsule-delivered saflufenacil.

Conclusions:

• Silk fibroin microencapsulation offers a viable route for creating biodegradable microcapsules with tunable properties.
• This approach addresses challenges in controlled release and scalable manufacturing for sustainable materials.
• The technology shows significant potential for applications in agrochemicals and cosmetics.