Magnetic antimicrobial nanocomposite based on bacterial cellulose and silver nanoparticles

A facile method was developed to prepare a magnetic Ag nanocomposite. The 3-D nanofibrous structure of bacterial cellulose (BC) was homogenized with a ferric and ferrous mixture by a high speed blender. Magnetite nanoparticles were precipitated and incorporated into BC nanostructure by adjusting the homogenate to alkaline pH. The magnetic BC nanofiber soaked in dopamine solution will be coated with an adherent self-polymerized polydopamine layer. Since the polydopamine surface is very effective for reducing silver ion, Ag nanoparticles were incorporated into the dopamine treated magnetic BC by soaking in silver nitrate solution. The magnetization of the as-prepared Ag nanocomposite was well maintained. The magnetic Ag nanocomposite possesses a high antimicrobial activity against the model microbes Escherichia coli and Bacillus subtilis. It also has potential as a mild fermentation medium sterilizing agent that a freshly prepared LB medium shows no appreciable contamination after incubating with Ag nanocomposite for 4 h and removed by an external magnet.