Destruction of Pseudomonas aeruginosa pre-formed biofilms by cationic polymer micelles bearing silver nanoparticles

Abstract

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen often associated with biofilm infections. This study evaluated the capacity for biofilm destruction of a novel combination of cationic polymer micelles formed from poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA-PCL-PDMAEMA) triblock copolymer either alone, or loaded with silver nanoparticles (M_AgNPs). Pre-formed P. aeruginosa biofilms were incubated with either blank micelles, AgNO₃, or M_AgNPs. Biofilm biomass (crystal violet assay), metabolic activity (Alamar blue reduction), structure (SEM) and viability (CLSM after Live/Dead staining, or plating for CFU) were checked. The results showed that the micelles alone loosened the biofilm matrix, and caused some alterations in the bacterial surface. AgNO₃ killed the bacteria in situ leaving dead biofilm bacteria on the surface. M_AgNPs combined the two types of activities causing significant biofilm reduction, and alteration and death of biofilm bacteria. Therefore, the applied PDMAEMA-based micelles appear to be a successful candidate for the treatment of P. aeruginosa biofilm infections.

Keywords:

• AgNPs-bearing cationic polymer micelles
• P. aeruginosa biofilm destruction
• PDMAEMA

Acknowledgements

A bilateral cooperation agreement between the Bulgarian Academy of Sciences and the Polish Academy of Sciences made possible the synthesis and characterization of the polymer system. The authors thank O. Stoitsov, MS in English Language, and a professional translator and interpreter for the EC, for critical reading of the English text.

Disclosure statement

The authors declare no conflict of interest in this work.

Compliance with ethics requirements

This article does not contain any studies with human or animal subjects.

Additional information

Funding

Dr Tsvetelina Paunova-Krasteva acknowledges the financial support received from the Bulgarian Ministry of Education and Science under the National Research Programme “Young scientists and postdoctoral students” approved by PMC № 577/17.08.2018.