Gram Negative Biofilms: Structural and Functional Responses to Destruction by Antibiotic-Loaded Mixed Polymeric...

Area of Science:

• Biomaterials Science
• Microbiology
• Drug Delivery Systems

Background:

• Bacterial biofilms are a major challenge in chronic infections, protecting bacteria via an extracellular matrix (ECM).
• Effective treatments require agents that disrupt biofilms, possess antibacterial activity, and can penetrate the ECM.
• Current therapies often struggle against the protective nature of biofilms.

Purpose of the Study:

• To develop novel mixed polymeric micelles (MPMs) capable of destroying biofilm ECM and delivering antibiotics.
• To load MPMs with ciprofloxacin or azithromycin for enhanced antibiofilm efficacy.
• To evaluate the antibiofilm activity and drug delivery capabilities of these MPMs against *Escherichia coli* and *Pseudomonas aeruginosa*.

Main Methods:

• Synthesis of mixed polymeric micelles (MPMs) using cationic (PDMAEMA-PCL-PDMAEMA) and non-ionic (PEO-PPO-PEO) triblock copolymers.
• Loading MPMs with ciprofloxacin or azithromycin.
• Application of MPMs on pre-formed *E. coli* and *P. aeruginosa* biofilms.
• Assessment of biofilm destruction, bacterial viability, and host tissue interaction using scanning electron microscopy and an ex vivo skin model.

Main Results:

• MPMs demonstrated significant biofilm destructive capabilities.
• Viability experiments confirmed successful drug delivery through the disrupted biofilm.
• Distinct patterns of bacterial cell alteration and host immune response (nitric oxide, IL-17A) were observed.
• MPMs showed efficacy against both laboratory strains and clinical isolates.

Conclusions:

• Developed MPMs are effective biofilm-ECM-destructive drug delivery systems.
• These MPMs offer a promising strategy for treating chronic bacterial infections associated with biofilms.
• The study highlights the potential of tailored polymeric micelles for advanced therapeutic applications.