Chitosan-stabilized gold nanoparticles supported on silica/titania magnetic xerogel applied as antibacterial system

The sol-gel method is an excellent choice to produce composite materials with enhanced performance by efficiently combining the individual features of their components. In this work, chitosan-stabilized gold nanoparticles (ChAuNPs) were immobilized onto a SiO2/TiO2 magnetic xerogel, which was synthesized through hetero-condensation of silica and titania precursors in the presence of magnetite particles covered with a silica shell. This system allies the antimicrobial capacity of ChAuNP, the surface reactivity of titania, porous structure of silica, and magnetic response of the magnetite particles. The magnetite phase was characterized by X-ray diffraction and the shape and size of the particles were observed by scanning and transmission electron microscopy. ChAuNPs were obtained in spherical shape with size below 10 nm, as characterized by UV–Vis spectroscopy and transmission electron microscopy. SiO2/TiO2 magnetic xerogel containing the ChAuNP was also characterized by thermogravimetric and textural analysis, transmission electron microscopy, and magnetism. The ChAuNP-SiO2/TiO2 magnetic xerogel is mesoporous with facile magnetic recovering and its performance as antimicrobial agent was assessed against the pathogen E. coli. The ChAuNP-SiO2/TiO2 magnetic xerogel presented inhibitory effect against the tested bacteria, even with such low gold content. After the magnetic recovering, the material was reused and maintained its antibacterial activity.