Multifunctional polypyrrole@maghemite@silver composites: synthesis, physico-chemical characterization and antibacterial properties

Maghemite (gamma-Fe2O3) nanoparticles were synthesized by coprecipitation of ferrous and ferric salts with ammonia and oxidation with sodium hypochlorite. Polypyrrole (PPy) was obtained, by the chemical oxidative polymerization of pyrrole in an aqueous solution in the presence of iron oxide nanoparticles. The morphology of PPy was turned from globular to nanofibers by addition of dyes. The resulting PPy@gamma-Fe2O3 hybrid composites were characterized by transmission electron microscopy, magnetic and electrical conductivity measurements and energy dispersive X-ray spectroscopy. Both the electrical conductivity and magnetic properties of the PPy@gamma-Fe2O3 nanocomposites were controlled by the maghemite content due to the insulating properties of magnetic iron oxide nanoparticles added to the conducting polymer. Antibacterial activity of all materials was defined by determination of minimal inhibitory concentration. Antibacterial properties of native materials were improved by the reduction of silver ions from an aqueous solution to obtain PPy@gamma-Fe2O3@silver composites. Due to the antibacterial properties of these composites, especially of those with silver particles, they can be considered for the applications where bacterial contamination can deteriorate the functionality of material.