Polymer multilayers with pH-triggered release of antibacterial agents.

Area of Science:

• Materials Science
• Biomedical Engineering
• Polymer Chemistry

Background:

• Developing effective antibacterial coatings for medical devices is crucial to prevent device-associated infections.
• Poly(methacrylic acid) (PMAA) hydrogels offer tunable properties for drug delivery applications.
• Controlling the release of antimicrobial agents (AmAs) based on environmental stimuli, like pH, is a key challenge.

Purpose of the Study:

• To investigate the layer-by-layer design of PMAA ultrathin hydrogel coatings for pH-responsive antimicrobial agent release.
• To evaluate the impact of different cross-linkers (adipic acid dihydrazide - AADH vs. ethylenediamine - EDA) on hydrogel properties and AmA release.
• To assess the antibacterial efficacy of released agents against Staphylococcus epidermidis.

Main Methods:

• Fabrication of PMAA ultrathin hydrogel coatings using layer-by-layer assembly.
• Incorporation of antimicrobial agents (gentamicin and L5 peptide) into the hydrogel matrix.
• Characterization of hydrogel hydrophobicity and AmA retention under varying salt concentrations.
• Investigation of AmA release profiles at different pH values.
• Testing the antibacterial activity of released L5 peptide against planktonic Staphylococcus epidermidis.
• Evaluation of Staphylococcus epidermidis adhesion and colonization on AmA-loaded hydrogel coatings.

Main Results:

• AADH-cross-linked PMAA hydrogels exhibited increased hydrophobicity and enhanced AmA retention in high-salt solutions compared to EDA-cross-linked hydrogels.
• AmA release was suppressed at low pH in AADH-cross-linked hydrogels.
• Released L5 peptide retained its antibacterial activity against Staphylococcus epidermidis.
• PMAA hydrogel coatings loaded with L5 peptide significantly inhibited Staphylococcus epidermidis adhesion and colonization.

Conclusions:

• Layer-by-layer design principles enable the creation of PMAA hydrogel coatings with tunable pH-responsive AmA release.
• AADH as a cross-linker improves AmA retention and modulates release kinetics.
• These hydrogel coatings demonstrate potential for developing effective antibacterial surfaces for medical devices, offering new avenues for studying host-pathogen interactions.