Silicon Nanowire Coatings for Mucosal Tissue Adhesion and Drug Delivery
K.E. Fischer, M.D. Bunger, G. Nagaraj, R.H. Daniels, E.M. Li, T.A. Desai
University of California, San Francisco, US
Keywords: bioadhesion, drug delivery, nanowires
Abstract:Mucosal tissues, such as buccal, intestinal, nasal, ocular, and vaginal surfaces, are optimal for therapeutic drug delivery because of their blood supply, surface area, and accessibility. However considerable barriers, such as mucous layers, enzymes, and cellular tight junctions, often prohibit therapeutic molecules from entering via these routes. Drug delivery devices may be used to protect against degradative agents such as enzymes, but are typically removed by the motile mucous layer. To improve residence times in close proximity to mucosal tissues, it is critical to adhere directly to the underlying cells. Silicon nanowires of diameter 60 nm and lengths up to 40 um have been shown to adhere to intestinal cell culture lines. However, the mechanisms of nanowire bioadhesion have not been thoroughly characterized. In this work, we found that nanowire-coated microspheres increased adhesion in several different mucosal tissues. Furthermore, using confocal microscopy, we have observed cellular remodeling in response to the nanowire stimuli. Scanning electron microscopy indicates interactions between micro and nanostructures on the cell surface and nanowires. Thus, we conclude that nanowires adhere to cells via cellular remodeling, in addition to typical surface area-dependent forces.