The Zinc oxide (ZnO) nanoparticle is a promising inclusion into the chitosan matrix as this metal oxide has low toxicity while being foulant-destroying. The anti-biofilm action of the chitosan/ZnO coating comes mainly from the inclusion of the ZnO into the chitosan matrix.
When exposed to light, ZnO undergoes photocatalytic reactions to produce reactive oxygen species (ROS) which act locally to damage and destroy microbes to reduce biofouling. Silver (Ag) nanoparticles are included into the chitosan-ZnO formulation to catalyze this light reaction.
Polyethylene glycol (PEG) is a non-toxic coating that consists of polymers end-attached to a surface forming a polymer 'brush' creating a physical barrier to biofouling. The high hydration level of this brush also makes microbial adhesion energetically unfavorable which therefore reduces biofilm formation.
Benzophenone-3 (BP-3) is a compound that is included in the chitosan matrix due to its hydrophobic nature. It is a UV-filter that is used commercially in sunscreen and cosmetic products.
This coating makes it difficult for bacteria to attach to the surface. The effect stems from the inclusion of a hydrophobic nanoparticle which affects the boundary layer of water close to the surface.
Bacteria will only attach loosely to this surface facilitating easy mechanical cleaning. This property results from the inclusion of a polymer brush border which makes bacterial attachment unfavorable due to steric repulsion.
This coating degrades bacteria within the biofilm. This occurs as reactive oxygen species are released into the biofilm where they destroy bacteria.
This formulation is a mixture of the base chitosan coatings and various nanoparticle inclusions. This generates an "ambiguous" interface between the surface and bacteria with the benefits of all included functionalities.
