Nanoparticles having amphiphilic silane containing Chlorin e6 with strong anti-biofilm activity against periodontitis-related pathogens

The objectives of this study were to: (1) develop the multifunctional nanoparticles containing Chlorin e6 (Ce6), Coumarin 6 (C6) and Fe3O4 nanoparticles (NPs); and (2) investigate the inhibitory effects of the nanoparticles via antibacterial photodynamic therapy (aPDT) against three species of periodontitis-related pathogens for the first time. Ce6 and C6 were co-loaded into the Fe3O4-silane core-shell structure to form multifunctional nanoparticles (denoted “Fe3O4[email protected]/C6 MNPs”). The physical and chemical properties of nanoparticles were characterized. Biofilm properties of Streptococcus sanguinis, Porphyromonas gingivalis and Fusobacterium nucleatum were tested. Colony-forming units (CFU), live/dead assay, and metabolic activity of biofilms were determined to evaluate the aPDT function mediated by the Fe3O4[email protected]/C6 MNPs. Fluorescence imaging and the targeted antibacterial effects were also investigated. Fe3O4[email protected]/C6 MNPs showed superparamagnetic properties, chemical stability and water-solubility, with no cytotoxicity. Fe3O4 NPs did not compromise the emission peaks of C6 and Ce6. The Fe3O4[email protected]/C6-mediated aPDT had much greater reduction in biofilms than the control groups (p < 0.05). Biofilm CFU was reduced by about 4–5 orders of magnitude via Fe3O4[email protected]/C6-mediated aPDT. The co-loading of Ce6 and C6 enabled the real-time aPDT monitoring by ratio emissions with the same wavelength. Fe3O4 with magnetic field enabled the targeting of infection sites by killing bacteria via magnetic field. The multifunctional nanoparticles exerted strong anti-biofilm activity against periodontitis-related pathogens, with excellent biocompatibility, real-time monitoring, and magnetically-targeting capacities. The multifunctional nanoparticles have great potential in antibacterial applications to inhibit the occurrence and progression of periodontitis.