|M.Sc Student||Otmazgin Shani|
|Subject||Permeation of Macromolecules Through the Mucosa Layer|
|Department||Department of Chemical Engineering||Supervisor||Professor Havazelet Bianco-Peled|
|Full Thesis text|
Peptides and proteins are becoming important therapeutic agents, but only few of them are being used as drugs because of obstacles related to their delivery. Oral delivery is not suitable for these sensitive drugs molecules since they might be damaged by the low pH in the stomach. An interesting alternative is transmucosal drug delivery which involves transport of pharmaceuticals through the nasal, buccal, vaginal, pulmonary, and other mucosa covered organs. This non-invasive rout of delivery has the potential to preserve macromolecule’s structure, however the mucous layer is a barrier that limits their diffusion. The mucous barrier does not have a significant effect on small uncharged molecule, as opposed to a large or charge molecule. In an attempt to overcome this limitation, it was suggested to transfer polypeptides and proteins drugs through the mucosa using substances termed penetration enhancers. Enhancers are known to increase the penetration rate of drugs through the epithelial cells layer found beneath the mucosa, but their influence on the mucosa itself is largely unexplored. Understanding the transport propertied of mucous and the effect that penetration enhancers have on it can help designing products able to overcome the mucosa barrier for delivery of macromolecules.
In this work, we investigated the effect of two penetration enhancers, Taurine (TAU) and N-Acetylcysteine (NAC), on the transport of the model macromolecule Blue Dextran (BD) through a mucous layer. We used home-made glass vertical Franz diffusion cell to study the permeation rates. Our results showed that BD permeation in the presence of TAU is greater than in the absence of TAU, while the permeability of BD was not improved at all in the presence of NAC. Small Angle X-ray Scattering measurements were used to characterize solutions of mucin, TAU, NAC, and their mixtures. These results showed that the X-ray scattering pattern of mucin did not change as a result of adding the permeation enhancers. Adding TAU and NAC to mucin decreased its viscosity. The viscosity of mucin in the presence of NAC was lower than mucin viscosity in the presence of TAU. FTIR spectroscopy was used to further characterize the interaction between the mucin and TAU or NAC. The results showed that TAU interacts with oligosaccharide in the mucin, as oppose to NAC which interacts with the proteins backbone of mucin. Based on our results it was suggested that TAU interacts with mucin’s oligosaccharides due to its positive charge. It affects BD diffusion by decreasing the resistance to transport through the dense oligosaccharide network and hence it increases the BD permeability. In contrast, NAC interacts with the sulfide group between the proteins in the mucous layer. However the resistance to transport induced by this protein network is small and therefore decreasing it further does not improve BD permeability.