Single-molecule lamellar hydrogels from bolaform microbial glucolipids

Area of Science:

• Soft matter physics
• Materials science
• Biochemistry

Background:

• Lipid lamellar hydrogels are rare soft fluids distinct from fibrillar networks.
• Their mechanical properties are typically governed by defects in lipid bilayers.
• Existing hydrogels often rely on polymers or surfactants to induce these defects.

Purpose of the Study:

• To report a new class of lipid lamellar hydrogels.
• To investigate hydrogels formed from a single bolaform glycosylated lipid produced via fermentation.
• To elucidate the relationship between material structure, defects, and mechanical properties.

Main Methods:

• Small-angle X-ray and neutron scattering (SAXS, SANS) for structural analysis.
• Polarized light microscopy to visualize defect-rich lamellar domains.
• Oscillatory rheology to characterize elastic properties and frequency dependence.

Main Results:

• The lipid self-organizes into flat, interdigitated membranes stabilized by electrostatic repulsion, forming micrometer-sized lamellar domains.
• Defects within membranes and domain interconnections dictate properties from nano- to micrometer scales.
• Rheology revealed weak power-law scaling of moduli with frequency, characteristic of fractional rheology models.
• The hydrogels display shear-thinning behavior with rapid recovery and ionic strength directly influences their elasticity.

Conclusions:

• A novel class of lipid lamellar hydrogels can be synthesized from a single fermented bolaform glycosylated lipid.
• The hydrogel's elasticity is intricately linked to membrane defects and domain morphology.
• Ionic strength is a critical factor in tuning both lamellar phase interactions and overall gel elasticity.