Management of oral biofilms by nisin delivery in adhesive microdevices.

Numerous beneficial microbes thrive in the oral cavity where they form biofilms on dental and mucosal surfaces to get access to nutrients, and to avoid being carried away with the saliva. However, biofilm formation is also a virulence factor as it also protects pathogenic bacteria, providing them with an environment for proliferation causing oral infections. Oral hygiene relies on mechanical removal of biofilms. Some oral care products also contain antimicrobials, but effective eradication of biofilms with antimicrobials requires both a high concentration and long exposure time. In the present communication, we investigate the potential of using miniaturized drug delivery devices, known as microcontainers (MCs), to deliver the antimicrobial peptide, nisin to an oral multi-species biofilm. MCs are loaded with nisin and X-ray micro-computed tomography reveals a full release of nisin through a chitosan lid within 15 min. Chitosan-coated MCs display substantial bioadhesion to the buccal mucosa compared to non-coated MCs (68.6 ± 14.3% vs 33.8 ± 5.2%). Confocal monitoring of multi-species biofilms reveals antibacterial effects of nisin-loaded chitosan-coated MCs with a faster onset (after 3 h) compared to solution-based delivery (after 9 h). Our study shows the potential of using MCs for treatment of multi-species oral biofilms and is encouraging for further design of drug delivery devices to treat oral diseases.

Mucin dispersions as a model for the oromucosal mucus layer in in vitro and ex vivo buccal permeability studies of small molecules.

The mucus layer is believed to play a part in drug permeation across the oral mucosa. Human freeze-dried saliva (HFDS) and porcine gastric mucin (PGM) was evaluated as model for mucus layer per se or in conjunction with in vitro and ex vivo buccal permeability models. Four small molecules (nicotine, mannitol, propranolol, caffeine) showed decreased permeability across mucin dispersions, compared to controls, and a greater effect was seen with HFDS than with PGM. Permeability of propranolol and caffeine across filter-grown TR146 cells was decreased by the presence of mucin, whereas no effect was found on nicotine and mannitol. Incubation of porcine buccal mucosa with mucin dispersions for 24 h compromised the integrity of the tissue, whereas 30 min incubation did not affect tissue integrity. Tissue incubation with mucin dispersions did not decrease nicotine permeability. For the studied model drugs, it is concluded that mucin dispersions constitute a minor barrier for drug diffusion compared to the epithelium.