This would either suppress diffusion of particles larger than the salivary mesh size or lead to immobilization because of interaction filtering. NP agglomeration, because of interactions with, e.g., salivary proteins and ions, would implicate a significant increase in size.
Thus, it still remains unclear whether NPs interact with components of UWMS, and how size and surface functionalization (charge) impact the colloidal stability and, consequently, the mobility of NPs as a function of the salivary microstructure. Thereby, the bound mucosal pellicle is formed, which is a supra-molecular film that functions as lubricant with high moisture retention capacity.Īlthough the impact of physicochemical properties of NPs on colloidal stability in artificial media simulating, e.g., salivary pH and ionic conditions and buccal cell uptake using serum-free culture medium or phosphate buffer has been demonstrated, to the best of the authors’ knowledge, no systematic investigation of well-defined NPs (i.e., NPs of nominal size, surface charge, and hydrophilicity) dispersed in relevant media including unstimulated whole-mouth saliva (UWMS) has been performed. These mucins, together with the membrane-associated epithelial MUC1, as well as sIgA, and cystatin adsorb on the epithelial cell surface by hydrophobic interactions, which was previously shown by Gibbins et al. This network is responsible for the gel-like structure and the viscoelastic properties of saliva, since the linked mucin fibers (elastic component) possess a high water binding capacity (viscous component). Moreover, the high-molecular-weight mucin MUC5B forms an entangled mucus network due to different intermolecular interactions, including calcium-mediated cross-links, hydrophobic interactions, and carbohydrate–carbohydrate interactions. Various proteins such as MUC7, secretory IgA, and lactoferrin are present in saliva, constituting the salivary immune defense system that promotes the clearance of xenobiotics due to agglomeration effects. Saliva is a hypotonic fluid with low ionic strength that contains calcium, phosphate, carbonate, and thiocyanate ions. However, during medical application, NPs encounter saliva as the first protective biological barrier. Thereby, transport of nanoparticles (NPs) occurs either via the transcellular or the paracellular pathway. The lining mucosa represents the larger part of the oral cavity and allows better absorption of drugs than the keratinized mucosa. Such systems can be transferred into films or gels that can be applied to the lining mucosa, e.g., to the inner side of the cheek.
One highly promising technological approach in this rapidly emerging field is the design of nanocarriers. Hence, there is a need for improvements of treatment strategies that will increase the efficiency of oral therapy. This is because the environmental conditions in the oral cavity, such as saliva-washing effects associated with accidental swallowing or enzymatic degradation of the drug, limit the usefulness of existing medications such as mouthwashes, gels, solutions, and oral suspensions. For example, infections, oral cancer, periodontal disease, and tooth decay are among the most common oral diseases that present a huge health problem.Īlthough significant advances in understanding the cellular and molecular events of oral diseases have been made, only a few approved therapies are available at present. However, general conditions may change this homeostasis and increase the risk of oral diseases and disorders.
Moreover, it facilitates chewing, biting, speaking, smiling, and, consequently, psychosocial well-being. It has a variety of functions, which closely work together, to prevent absorption of foreign substances, maintain the oral ecosystem, and support the digestion process. The mouth is a well-organized system, often referred as the mirror of the body that reflects and supports human health.
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