Cellular interactions of surface modified nanoporous silicon particles.

In this study, the self-assembly of hydrophobin class II (HFBII) on the surface of thermally hydrocarbonized porous silicon (THCPSi) nanoparticles was investigated. The HFBII-coating converted the hydrophobic particles into more hydrophilic ones, improved the particles' cell viability in both HT-29 and Caco-2 cell lines compared to uncoated particles, and enhanced the particles' cellular association. The amount of HFBII adsorbed onto the particles was also successfully quantified by both the BCA assay and a HPLC method. Importantly, the permeation of a poorly water-soluble drug, indomethacin, loaded into THCPSi particles across Caco-2 monolayers was not affected by the protein coating. In addition, (125)I-radiolabelled HFBII did not extensively permeate the Caco-2 monolayer and was found to be stably adsorbed onto the THCPSi nanoparticles incubated in pH 7.4, which renders the particles the possibility for further track-imaging applications. The results highlight the potential of HFBII coating for improving wettability, increasing biocompatibility and possible intestinal association of PSi nanoparticulates for drug delivery applications.