Self-defensive layer-by-layer films with bacteria-triggered antibiotic release.

Area of Science:

• Materials Science
• Biomedical Engineering
• Nanotechnology

Background:

• Bacterial infections on biomedical devices are a major clinical challenge.
• Antibiotic resistance necessitates novel strategies for localized antibacterial delivery.
• Controlled-release systems are crucial for preventing device-associated infections.

Purpose of the Study:

• To develop bioresponsive, controlled-release antibacterial coatings using tannic acid and cationic antibiotics.
• To investigate the influence of assembly technique on coating properties and antibiotic release.
• To evaluate the antibacterial efficacy and cytocompatibility of the developed coatings.

Main Methods:

• Layer-by-layer (LbL) assembly of tannic acid with tobramycin, gentamicin, or polymyxin B.
• Spin-assisted and dip-assisted deposition techniques.
• Characterization using ellipsometry, UV-Vis spectroscopy, and mass spectrometry.
• In vitro evaluation of antibiotic release, bacterial inhibition, and osteoblast cell proliferation.

Main Results:

• LbL coatings demonstrated pH-triggered antibiotic release in response to bacterial acidification.
• Spin-assisted films showed tunable morphology (2D to 3D) based on thickness and spinning rate.
• Coatings exhibited minimal antibiotic release at physiological pH (7.4), preventing resistance development.
• Effective inhibition of Staphylococcus epidermidis and Escherichia coli growth was observed.
• Coatings supported murine osteoblast cell adhesion and proliferation.

Conclusions:

• Tannic acid-based coatings offer a promising strategy for localized, bacteria-triggered antibacterial delivery.
• Assembly technique significantly impacts coating morphology and release kinetics.
• These bioresponsive coatings can prevent bacterial colonization on biomedical devices while remaining cytocompatible.