pH-Triggered Silk Fibroin/Alginate Structures Fabricated in Aqueous Two-Phase System

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Separation Science

Background:

• Aqueous two-phase systems (ATPS) are crucial for bioseparations and biomaterial applications.
• Developing novel polymer pairs for ATPS expands their utility.
• Silk fibroin (SF) and alginate offer unique properties for new ATPS development.

Purpose of the Study:

• To introduce a novel ATPS based on silk fibroin (SF) and alginate.
• To characterize the phase behavior and pH-triggered transition of the SF/alginate ATPS.
• To demonstrate potential applications of this new biphasic system.

Main Methods:

• Phase diagram construction to determine critical concentrations for SF/alginate ATPS formation.
• pH-dependent analysis of the system's phase behavior.
• Characterization using circular dichroism, fluorescence spectroscopy, dynamic light scattering, and zeta potential measurements.

Main Results:

• A novel SF/alginate ATPS was successfully established.
• The system exhibits a pH-triggered phase transition, becoming single-phasic above pH ~9.5.
• SF chain extension at higher pH was identified as the mechanism for the phase transition.
• Demonstrated applications include compartmentalized immunoassays, controlled release, and hierarchical fiber fabrication.

Conclusions:

• The SF/alginate ATPS represents a novel, pH-responsive biphasic system.
• The pH-triggered transition is driven by conformational changes in silk fibroin.
• This system holds significant promise for advanced applications in biotechnology and materials science.