Inducing Microscale Structural Order in Phage Nanofilament Hydrogels with Globular Proteins

Area of Science:

• Biomaterials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Biological hydrogels are crucial for physiological functions, often featuring ordered structures for mechanical strength and tissue-specific properties.
• Filamentous bacteriophages, high aspect ratio nanofilaments, self-assemble into liquid crystalline domains, mimicking biological hydrogels for biomedical engineering.
• Previous work formed M13 phage hydrogels at high concentrations, resulting in tightly packed microstructures and high stiffness.

Purpose of the Study:

• To develop a method for self-assembling filamentous phage into liquid crystalline hydrogels at significantly lower concentrations than previously achieved.
• To create hybrid hydrogels using M13 phage and bovine serum albumin (BSA) and investigate their properties.
• To explore the potential of these hybrid hydrogels for tunable mechanical properties and biomedical applications.

Main Methods:

• Inducing self-assembly of M13 phage into liquid crystalline hydrogels at concentrations orders of magnitude lower than lyotropic liquid crystal formation.
• Forming hybrid hydrogels with M13 phage and bovine serum albumin (0.25 w/v%).
• Characterizing water adsorption, self-healing capabilities, autofluorescence, antibacterial activity, and mechanical properties (compression modulus).

Main Results:

• Hybrid hydrogels adsorbed up to 16 times their weight in water, outperforming BSA-only hydrogels.
• The hybrid hydrogels exhibited repetitive self-healing under physiological conditions and room temperature.
• The M13-BSA hydrogels demonstrated autofluorescence in three channels and antibacterial activity against *Escherichia coli*.
• Compared to tightly packed M13-only hydrogels, the hybrid hydrogels had a 2x lower compression modulus, indicating tunable mechanical properties.

Conclusions:

• A novel method allows M13 phage self-assembly into ordered hydrogels at low concentrations, creating less densely packed microstructures.
• Hybrid hydrogels formed with M13 phage and BSA exhibit synergistic gelation, enhanced water absorption, self-healing, autofluorescence, and antibacterial properties.
• The addition of globular proteins like BSA allows for tunable mechanical properties and pore structure in filamentous phage-based hydrogels while maintaining bioactivity and microscale order.