Layer-by-layer self-assembly for fabrication of recyclable magnetic antimicrobial nanocomposites

Layer-by-layer (LbL) assembly is a prevalent approach for coating material with functional thin films. In this work, we report on high-efficient antibacterial nanofilms constructed by direct assembly of sodium citrate with synthetic N-halamine precursor containing quaternary ammonium salt (QAS) moieties, and deposited on the iron oxide nanoparticles (IO NPs) (size 20~30 nm) using the LbL method. The chlorinated magnetic nanoparticles were characterized by Transmission electron microscopy, Thermogravimetric analysis, Zeta Potential analyses, Fourier transform infrared spectroscopy, X-Ray powder diffraction and Saturation magnetization value measurement. The biocidal kinetic test showed that the as-prepared nanoparticles had excellent biocidal activity towards both S. aureus (gram-positive) and E.coli (gram-negative) with short contact. In addition, functionalized magnetic nanocomposites can be easily recycled by an external magnetic field. The LbL assembly strategy provides possibility for the development of novel antimicrobial coatings via an eco-friendly approach.