Fundamental nanoparticle interactions with biofilms of Pseudomonas species

The use of engineered nanoparticles (NPs) as a technique for antimicrobial delivery aimed at biofilm treatment is an emerging field of research. There have been numerous studies involving a wide range of NPs showing varying results regarding anti-bacterial effects (1). However, research focusing on specific interactions between functionalized nanoparticles and the extracellular polymeric substances (EPS) of biofilms are limited. The complexity of the biofilm matrix may be hindering the understanding of the fundamentals which govern biofilm – nanoparticle interactions. There are a wide range of physicochemical properties which influence the uptake and retention of nanoparticles within the matrix including NP size and charge properties, biofilm topography and porosity and EPS composition (2). These aspects must be considered when studying biofilm – nanoparticle interactions. In order to identify these specific interactions, a series of experiments were carried out using mCherry-expressing Pseudomonas fluorescens and GFP-expressing Pseudomonas putida biofilms. Using high throughput fluorescent intensity measurements and confocal microscopy, it was possible to investigate the uptake of surface functionalized silica NPs by the two biofilms and obtain valuable information regarding biofilm – nanoparticle interactions. The results suggest that specific NP surface functionalization has a major role in guiding the interaction and binding of EPS components, possibly due to electrostatic interactions between NPs and the EPS. The findings of this research will help with the future design of nanoparticles with specific modes of action towards components in the EPS.1. Ramos M., et al. (2018). International Journal of Nanomedicine13 : 1179–1213.2. Nevius BA., et al.(2012). Ecotoxicology21 : 2205–2213.