Antibiofilm Activity of Epoxy/Ag-TiO₂ Polymer Nanocomposite Coatings against Staphylococcus Aureus and Escherichia Coli

Dispersion of functional inorganic nano-fillers like TiO₂ within polymer matrix is known to impart excellent photobactericidal activity to the composite. Epoxy resin systems with Ag⁺ ion doped TiO₂ can have combination of excellent biocidal characteristics of silver and the photocatalytic properties of TiO₂. The inorganic antimicrobial incorporation into an epoxy polymeric matrix was achieved by sonicating laboratory-made nano-scale anatase TiO₂ and Ag-TiO₂ into the industrial grade epoxy resin. The resulting epoxy composite had ratios of 0.5–2.0 wt% of nano-filler content. The process of dispersion of Ag-TiO₂ in the epoxy resin resulted in concomitant in situ synthesis of silver nanoparticles due to photoreduction of Ag⁺ ion. The composite materials were characterized by DSC and SEM. The glass transition temperature (T_g) increased with the incorporation of the nanofillers over the neat polymer. The materials synthesized were coated on glass petri dish. Anti-biofilm property of coated material due to combined release of biocide, and photocatalytic activity under static conditions in petri dish was evaluated against Staphylococcus aureus ATCC6538 and Escherichia coli K-12 under UV irradiation using a crystal violet binding assay. Prepared composite showed significant inhibition of biofilm development in both the organisms. Our studies indicate that the effective dispersion and optimal release of biocidal agents was responsible for anti-biofilm activity of the surface. The reported thermoset coating materials can be used as bactericidal surfaces either in industrial or healthcare settings to reduce the microbial loads.