Abstract
Oral ulcers are widely prevalent, affecting approximately 20-25% of the global population. Current treatment primarily focuses on pain reduction highlighting the need for new treatment options that focus on healing. Mānuka oil has been used for centuries by Māori and possesses antimicrobial and anti-inflammatory properties with low minimum inhibitory concentrations(MIC) against a range of bacteria. We aimed to design and produce oral fast disintegrating wafers with <1 mm thickness profile that incorporated mānuka oil or β-triketone loaded nanoparticles that can adhere to an ulcer site, disintegrate in <60 seconds and release nanoparticles that remain on the wound site promoting healing. D-mannitol, gelatine, peppermint extract and nanoparticles encapsulating mānuka oil/β-triketone were dissolved at 37°C in dH2O and allowed to set in 1 cm diameter moulds, then lyophilised to produce orally fast disintegrating wafers. Wafer thickness and disintegration time were measured to meet the thresholds of <1mm and <60 s observed in the literature. Contact angle was measured over 60 seconds to assess hydrophobicity and wettability of the wafers. Characterisation was also conducted using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to examine the surface morphology and identify components within each wafer. Muco-adhesion and retention were tested by attaching the wafers to pig buccal mucosa, artificial saliva was pumped over the top at 410 μL/min for 3 minutes at 37°C. The cytotoxicity of the wafers was investigated via a PrestoBlue® assay using primary gingival keratinocytes after 24 hours of exposure with the wafers, and fluorescence measured at 590 nm. Disc diffusion assays were conducted against Streptococcus mitis (S. mitis) and Oxford strain Staphylococcus aureus (S. oxford) to determine antimicrobial activity of the wafers compared to nanoparticles alone. Inhibition zones were measured using ImageJ after a 24-hour incubation. The final wafers possessed desirable characteristics including a disintegration time of <60 seconds and thickness <1 mm. The successful incorporation of β-triketone and mānuka oil nanoparticles was confirmed by SEM and FTIR, confirming their presence via bands indicative of individual components associated with nanoparticles, and surface SEM allowing visualisation of nanoparticles embedded into the surface of the matrix. Contact angles <90° demonstrated the hydrophilic nature of the wafers. Wafers containing nanoparticles adhered and retained to ii the pig mucosa after 3 minutes of salivary flow, whilst wafers containing no nanoparticles started to dissolve. Disc diffusion assays displayed antimicrobial activity against S. mitis and S. oxford for mānuka oil/β-triketone wafers with a stronger antimicrobial effect being elicited against S. mitis. PrestoBlue® assay results showed potential cytotoxic effects of mānuka oil/β-triketone wafers with a decrease in fluorescence observed in comparison to the control after 24 hours. In conclusion, oral disintegrating wafers containing encapsulated mānuka/β-triketone oil nanoparticles can successfully be produced with desirable characteristics for intraoral applications. Future studies would examine in vivo efficacy and safety data and explore other potential applications for the wafer technology.