Preparation, characterization and long-term antibacterial activity of nisin anchored magnetic cellulose beads

Along with the concerns for food safety and environment, the demand of cost-effective and biodegradable materials in food treatment is increasing. In order to solve the problem of certain spoilage microorganisms, nisin anchored cellulose beads were prepared by a sol-gel transition method. By mixing gamma-Fe2O3 nanoparticles with cellulose in 8% LiOH center dot H2O/15% urea aqueous solution precooled at - 20 degrees C, regenerated cellulose beads mixed with gamma-Fe2O3 nanoparticles (RC) were fabricated via a dropping technology. Subsequently, cellulose beads were oxidized by sodium periodate in dark room and nisin was anchored on the beads (NCs) through Schiff base reaction. The oxidization process and grafting reaction between the amino groups of nisin and the aldehyde groups of oxidized cellulose were confirmed via Fourier transform infrared spectra, field emission scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction. The beads containing gamma-Fe2O3 nanoparticles exhibits the sensitive magnetic response and excellent thermal stability with decomposition temperature over 200 degrees C. A long-term antimicrobial activity against Alicyclobacillus acidoterrestris DSM 3922 were investigated. To the best of our knowledge, this is the first report of such nisin-anchored beads. The biodegradable nisin-anchored beads are novel antimicrobial materials with great potential in food industry.