Antimicrobial applications of electroactive PVK-SWNT nanocomposites

The antibacterial properties of a nanocomposite containing an electroactive polymer, polyvinyl-N-carbazole (PVK) (97 wt %), and single-walled carbon nanotubes (SWNT) (3 wt %) was investigated as suspensions in water and as thin film coatings. The toxic effects of four different PVK-SWNT (97:3 wt %) nanocomposite concentrations (1, 0.5, 0.05, and 0.01 mg/mL) containing 0.03, 0.015, 0.0015, and 0.0003 mg/mL of SWNT, respectively, were determined for planktonic cells and biofilms of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis). The results showed that the nanocomposite PVK-SWNT had antibacterial activity on planktonic cells and biofilms at all concentration levels. Higher bacterial inactivation (94% for E. coli and 90% for B. subtilis) were achieved in planktonic cells at a PVK-SWNT concentration of 1 mg/mL. Atomic force microscopy (AFM) imaging showed significant reduction of biofilm growth on PVK-SWNT coated surfaces. This study established for the first time that the improved dispersion of SWNTs in aqueous solutions in the presence of PVK enhances the antimicrobial effects of SWNTs at very low concentrations. Furthermore, PVK-SWNT can be used as an effective thin film coating material to resist biofilm formation.