Self-Defensive Antimicrobial Surfaces Using Polymyxin-Loaded Poly(styrene sulfonate) Microgels

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Antimicrobial Technology

Background:

• Self-defensive antimicrobial surfaces aim to prevent bacterial colonization without constant antimicrobial release.
• Microgel coatings loaded with antimicrobials offer a promising strategy for controlled release.
• Complexation strength between microgels and antimicrobials is crucial for efficacy and safety.

Purpose of the Study:

• To compare the complexation strength of colistin and polymyxin B with poly(styrene sulfonate) (PSS) microgels.
• To evaluate the stability and release characteristics of these antibiotic-loaded microgels.
• To assess the antimicrobial efficacy and biocompatibility of the developed self-defensive surfaces.

Main Methods:

• Coarse-grained molecular dynamics simulations to predict complexation free-energy changes.
• In situ optical microscopy to observe microgel deswelling and stability under varying salt concentrations.
• In vitro bacterial killing assays and human fetal osteoblast cell culture experiments.

Main Results:

• Molecular dynamics indicated stronger complexation between polymyxin B and PSS microgels compared to colistin.
• Polymyxin B-loaded microgels exhibited enhanced stability in higher salt concentrations.
• Surfaces demonstrated effective killing of E. coli via contact-transfer mechanism while supporting osteoblast growth.

Conclusions:

• Polymyxin B offers superior complexation with PSS microgels, leading to more stable antimicrobial surfaces.
• These self-defensive surfaces show potential for physiological applications, triggered by bacterial presence.
• The developed surfaces provide a novel approach for combating bacterial infections without harming host cells.