In vivo penetration of bare and lipid-coated silica nanoparticles across the human stratum corneum

- Hydrophilic colloidal silica skin penetration was quantified on humans.
- Surface polarity plays a predominant role on the size in silica penetration process.
- Hydrophobic surface polarity of silica promotes skin penetration.
- Hair follicle density affects skin penetration of hydrophobized silica.