Low intensity electric field inactivation of Gram-positive and Gram-negative bacteria via metal-free polymeric composite

• Published in: Materials Science & Engineering C 2019-06, Vol.99, p.827-837
• Main Authors: da Silva Jr, Fernando A.G., Alcaraz-Espinoza, Jose Jarib, da Costa, Mateus M., de Oliveira, Helinando P.
• Format: Article
• Language: English
• Subjects: Antibacterial; Antibacterial activity; Antibacterial materials; Bacteria; Bacterial inactivation; Biofilm; Biofilms; Bioreactors; Carbon nanotubes; Composite materials; Deactivation; E coli; Electric fields; Electric potential; Electrodes; Gram-negative bacteria; Inactivation; Inhibition; Materials science; Metals; Nanotechnology; Nanotubes; Oxidation; Polypyrrole; Polypyrroles; Polyurethane; Polyurethane resins; Sandpaper; Substrates; Surgical implants; Voltage
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/j.msec.2019.02.027

The adhesion of pathogenic bacteria in medical implants and surfaces is a health-related problem that requires strong inhibition against bacterial growth and attachment. In this work, we have explored the enhancement in the antibacterial activity of metal free-based composites under external electric field. It affects the oxidation degree of polypyrrole-based electrodes and consequently the antibacterial activity of the material. A conductive layer of carbon nanotubes (graphite) was deposited on porous substrate of polyurethane (sandpaper) and covered by polypyrrole, providing highly conductive electrodes characterized by intrinsic antibacterial activity and reinforced by electro-enhanced effect due to the external electric field. The bacterial inhibition of composites was monitored from counting of viable cells at different voltage/time of treatment and determination of biofilm inhibition on electrodes and reactors. The external voltage on electrodes reduces the threshold time for complete bacterial inactivation of PPy-based composites to values in order of 30 min for Staphylococcus aureus and 60 min for Escherichia coli. [Display omitted] •Composites of polypyrrole and carbon allotropes present enhanced antibacterial capabilities.•The antibacterial efficiency of composites is enhanced by applying an electric field.•The external voltage reduces the threshold time for bacterial inactivation.