You're absolutely right -- there are some materials that would be very bad candidates here. I was pointing out only that this can be achieved with structure on

You're absolutely right -- there are some materials that would be very bad candidates here. I was pointing out only that this can be achieved with structure only (no additional hydrophobic/hydrophilic chemicals), and that it can be done with materials that have already proven themselves inert when ingested in nano-scale particle sizes.