Investigation into the physicochemical interactions of silica nanoparticles and EPS biomolecules within the biofilm matrix of Pseudomonas spp.

Difficulties in the removal of bacterial biofilms in the industrial and biomedical sectors have driven the development of new technologies. Although numerous studies have highlighted the use of nanoparticles (NPs) as antibiofilm agents, the fundamental physicochemical interactions between NPs and the biofilm matrix is still poorly understood 1. The development of ‘smart nanoparticles’ for biofilm removal requires an in-depth understanding of the complex interactions between NPs and biomolecules within the extracellular polymeric substances (EPS) of the biofilm matrix. These interactions are highly dependent on the physical and chemical properties of the NPs 2. In order to identify and characterize the specificity of binding and the direct interaction between silica NPs (SiNPs) and EPS matrix components of Pseudomonas spp. biofilms, a range of experiments were carried out. Biofilms were exposed to SiNPs of different sizes, charges and surface functionalization while biomolecules such as proteins, polysaccharides, and eDNA were fluorescently labelled and their distribution, relative abundance and their colocalization with SiNPs within the biofilm was quantitatively assessed using CLSM microscopy. Changes to the SiNPs size and surface-chemistry dramatically affected their interactions with biomolecules in the biofilm matrix. This includes the increased affinity (or interaction) of SiNPs to preferentially bind to proteins and beta-linked polysaccharides and also lead to changes in the degree to which aggregation of SiNPs occurs within and on the surface of the biofilm.

1. Ikuma K et al. (2015). Front. Microbiol. 6, 591

2. Bewersdorff, et al. (2017). Int. J. Nanomed. 12, 2001–2019