Polymer grafted recyclable magnetic nanoparticles

This work reports on a new combination of recyclable magnetic nanoparticles, polymers and antibiotics that show increased effectiveness in combating bacterial infections. The direct-coprecipitation of iron salts strategy was used to generate superparamagnetic nanoparticles with a saturation magnetization of 59.5 emu g−1. A silica coating was applied and used to stabilize the magnetic nanoparticles and create a convenient platform for further functionalization. A variety of PMAA brushes with different lengths and densities were prepared on the magnetic nanoparticles with an average diameter size as small as 10 nm via surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization of methacrylic acid. The polymer grafted magnetic nanoparticles were removed from water solutions after antimicrobial testing using a magnet, thereby avoiding nano-based pollution of the environment. The bioactivity of an antibiotic (penicillin-G) over bacteria (Staphylococcus aureus and Escherichia coli) was significantly enhanced when physically bound to the PMAA grafted magnetic nanoparticles. The inhibition activity of the penicillin-nanoparticle complex was retained using recycled magnetic nanoparticles that had been reloaded with penicillin-G.