Vancomycin-modified LaB6@SiO2/Fe3O4 composite nanoparticles for near-infrared photothermal ablation of bacteria.

LaB6 nanoparticles possess excellent near-infrared (NIR) photothermal conversion properties. Vancomycin can interact strongly with a broad range of Gram-positive and Gram-negative bacteria. Fe3O4 nanoparticles could be used as the carrier for magnetic separation. In this work, vancomycin and Fe3O4 nanoparticles were successfully bound onto the surface of LaB6 nanoparticles with a silica coating and carboxyl functionalization to fabricate vancomycin-modified LaB6@SiO2/Fe3O4 (Van-LaB6@SiO2/Fe3O4) composite nanoparticles as a novel nanomaterial for the NIR photothermal ablation of bacteria. From the analyses of absorption spectra, transmission electron microscopy images and X-ray diffraction patterns, the formation of Van-LaB6@SiO2/Fe3O4 composite nanoparticles was confirmed. The resulting Van-LaB6@SiO2/Fe3O4 composite nanoparticles possessed nearly superparamagnetic properties, retained the excellent NIR photothermal conversion property of LaB6 nanoparticles and could capture the bacteria Staphylococcus aureus and Escherichia coli efficiently. Owing to these capabilities, they were demonstrated to be quite efficient for the magnetic separation and NIR photothermal ablation of S. aureus and E. coli. Furthermore, the magnetic property made the Van-LaB6@SiO2/Fe3O4 composite nanoparticles useful for the magnetic assembling of bacteria, which could further enhance the photothermal ablation efficiency.