Materials Highlights

There is a growing interest in the use of melatonin in preventing radiation-induced mucositis with potential beneficial effects including prevention of mucosal damage, the emergence of ulcers and the loss of proliferative progenitor stem cells caused by radiation. Local drug delivery to the oral cavity is influenced by the oral mucosal pellicle which serves as a protective barrier between the oral epithelial surface and the external environment. In this study, we explore two key areas. Firstly, the use of thermal inkjet printing to improve the precision of drug deposition on polymeric oral films. Secondly, investigate melatonin release and penetration across an ex vivo oral mucosal pellicle model into the epithelial cancer cell line (TR146 cells). Our findings show that the deposited melatonin crystallized on the surface of the Polyvinyl Alcohol (PVA) film as the jetted droplets dried, consistent with previous work on in-jetted pharmaceutical solutions. The solid state of the deposited melatonin was further confirmed in attenuated total reflection Fourier transform infrared studies as crystalline. In addition, no new bonds detected which indicates the absence of new chemical bonds and interactions between melatonin and PVA. Investigating melatonin release and penetration across ex vivo oral mucosal pellicle model into the epithelial cancer cell line (TR146 cells) found that the amount of melatonin released was lower in the presence of saliva, likely due to the saliva initiating the formation of the mucosal pellicle through mucin–mucin interactions.