UCLA

Mesoporous silica nanoparticles (MSNs) have been shown to be useful in numerous applications, because the surface can be easily modified with various functional groups. MSNs can also be modified with respect to the interior or exterior of the particles: materials can be condensed within the silica framework, attached along the pore walls, or bound to the outer surface of the nanoparticles. Surface modifications with molecular machines can act to contain cargo molecules within the porous structure for stimulated release of the cargo. Additionally, materials have been developed that contain small metal oxide nanocrystals (d = 10-20 nm) encapsulated within a single MSN. These core-shell mesoporous materials can be used to examine toxicological properties of dissolved ions apart from their cell-surface interactions, since the porous shell allows for diffusion of ions through the porous channels, while also physically isolating the nanocrystal surface from direct contact with the biological material. Additionally, the outer surface of these core-shell MSNs can be modified with molecular machines for cargo storage and release. When iron oxide nanocrystals are encapsulated within MSNs that are equipped with nanovalves and exposed to high-frequency magnetic fields, the valves open and release cargo molecules from the nanoparticles. This property is used to deliver drug molecules in vitro. Furthermore, molecules can be covalently attached to the surface to direct the nanoparticles into certain cells. Cancer cells overexpressing transferrin receptors show enhanced uptake toward MSNs functionalized with surface-attached transferrin. When examined in vitro, these particles show increased uptake of MSNs compared to MSNs without surface-attached transferrin. This dissertation will include research on these two major research aims using MSNs: biological aims of specific drug delivery into target cells; and examining the environmental toxicity of engineered nanomaterials.