Biocompatible Rhamnolipid Self-Assemblies with pH-Responsive Antimicrobial Activity

Area of Science:

• Biomaterials Science
• Supramolecular Chemistry
• Antimicrobial Research

Background:

• Growing antibiotic resistance necessitates novel antimicrobial strategies.
• Development of biocompatible materials for targeted bacterial infection treatment is crucial.
• Lipid-based self-assembly offers a platform for advanced functional materials.

Purpose of the Study:

• To create a pH-switchable antimicrobial material using rhamnolipids (RL) and glycerol monooleate (GMO).
• To investigate the structure-activity relationship of RL/GMO supramolecular dispersions.
• To optimize the material for targeting bacteria in acidic wound environments.

Main Methods:

• Synthesis and characterization of RL/GMO supramolecular dispersions.
• Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) for structural analysis.
• Dynamic light scattering (DLS) for colloidal stability assessment.
• Antimicrobial efficacy testing against Staphylococcus aureus and MRSA at varying pH.

Main Results:

• RL/GMO dispersions exhibit a pH-triggered inverse-type liquid crystalline cubic structure.
• Effective reduction of Staphylococcus aureus populations (7-log) and prevention of biofilm formation at pH 5.0.
• Activity against MRSA with a minimum inhibitory concentration of 128 µg mL⁻¹ at pH 5.0.
• No significant activity observed against Gram-negative bacteria or at neutral pH.

Conclusions:

• A biocompatible, pH-switchable antimicrobial material was successfully developed.
• The study provides fundamental insights into lipid self-assembly for biomaterial design.
• This work guides the development of bio-based alternatives to combat antibiotic-resistant bacteria.