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Porous silicon (PSi) particles have been studied for the effects they elicit in Caco-2 and RAW 264.7 macrophage cells in terms of toxicity, oxidative stress, and inflammatory response. The most suitable particles were then functionalized with a novel 18 F label to assess their biodistribution after enteral and parenteral administration in a rat model. The results show that thermally hydrocarbonized porous silicon (THCPSi) nanoparticles did not induce any significant toxicity, oxidative stress, or inflammatory response in Caco-2 and RAW 264.7 macrophage cells. Fluorescently labeled nanoparticles were associated with the cells surface but were not extensively internalized. Biodistribution studies in rats using novel 18 F-labeled THCPSi nanoparticles demonstrated that the particles passed intact through the gastrointestinal tract after oral administration and were also not absorbed from a subcutaneous deposit. After intravenous administration, the particles were found mainly in the liver and spleen, indicating rapid removal from the circulation. Overall, these silicon-based nanosystems exhibit excellent in vivo stability, low cytotoxicity, and nonimmunogenic profiles, ideal for oral drug delivery purposes.

Immunoadjuvant porous silicon (PSi)-based nanovaccines are prepared by nanoprecipitation in a glass capillary microfluidics device. Vesicles, derived from cancer cell membranes encapsulating thermally oxidized PSi nanoparticles or PSi-polymer nanosystems binding a model antigen, are biocompatible over a wide range of concentrations, and show immunostimulant properties in human cells, promoting the expression of co-stimulatory signals and the secretion of pro-inflammatory cytokines.

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