The interaction of nanoparticles with mucosal barriers

Abstract

The aim of this thesis was to assess the safety profile of different novel nanoparticles when interacting with lung bronchial epithelial cells in vitro, especially their role in inflammation and cytotoxicity. In addition, the permeation behaviour of self-nanoemulsifying drug delivery systems (SNEDDS) was measured by a novel mucus diffusion model utilizing standardized transwell diffusion plates. Methods: Primary bronchial epithelial and Calu-3 cells were cultured in 24 and 96 well plates. Different formulations of nanoparticles (NPs) were used to measure IL-8 production by cells as a marker of inflammation (measured by sandwich ELISA). The Celltitre blue (CTB) and MTT assays were used to test cell viability. The effect of cell density on the CTB assay was studied (500k, 400k, 300k, 200k, 100k, 50k, 42k, 33k, 25k, 17k, and 8.3k) in 24 well plates. Permeation studies were examined by using a mucus diffusion model. The rheology of the mucus was investigated to evaluate the gel structure of the mucus. Results: The viability of cell exposed to 52nm polystyrene NPs showed no statistical difference between cells with NPs and cells without NPs after 24 hour of exposure. The nanoparticles were shown to interfere with both the CTB and MTT assays. The standard curves in the CTB assay vary as the cell density decreased. Although IL-8 was shown to be slightly increased in human primary cells after exposure to different concentrations of NPs, IL-8 increased significantly after exposures to the same proportion of sterile water as these nanoparticles were delivered in (a control for osmolarity). The composition of SNEDDS might play a major role in their capacity to permeate the mucus such as lauroglycol. The small intestine mucus gels have some degree of frequency dependency; between 0.1 and 1 Hz, there was a decline in both iv G` and Gʺ followed by a rise over 1-10Hz. Gʺ increased relative to G` suggesting a tendency to flow. This change at high frequency is verified by an increase in the phase angle, demonstrating a weaker gel. This biphasic behaviour may be explained by the gel forming interactions having time to break and make at a low frequency but at a high frequency, they do not have time to reform. Conclusion: I have found that both CTB and MTT assays may not be sensitive enough to test viability of cells exposed to nanoparticles. Therefore, other assay systems are required to test these NPs with respect to cytotoxicity. The composition of the SNEDDS played an important role in determining the permeation of the mucus gel layer.