Skin penetration of silica nanoparticles (NP) currently used in pharmaceutical and cosmetic products is atopic of interest not only to evaluate their possible toxicity, but also to understand their behaviour uponcontact with the skin and to exploit their potential positive effects in drug or cosmetic delivery field.Therefore, the present work aimed to elucidate the in vivo mechanism by which amorphous hydrophilicsilica NP enter human stratum corneum (SC) through the evaluation of the role played by the nanoparticlesurface polarity and the human hair follicle density. Two silica samples, bare hydrophilic silica (B-silica,162 ± 51 nm in size) and hydrophobic lipid-coated silica (LC-silica, 363 ± 74 nm in size) were appliedon both the volar and dorsal side of volunteer forearms. Twelve repetitive stripped tapes were removedfrom the human skin and evaluated for elemental composition by Energy Dispersive X-ray (EDX) analysisand for silicon content by Inductively Coupled Plasma quadrupole Mass Spectrometry (ICP-MS). All thestripped tapes revealed nanosized structures generally located in the broad spaces between corneocytesand characterized by the same elemental composition (relative weight percentage of silicon and siliconto oxygen weight ratio) than that of the applied samples. However, only about 10% B-silica permeateduntil the deepest SC layers considered in the study indicating a silica retention in the upper layers ofSC, regardless of the hair follicle density. Otherwise, the exposure to LC-silica led to a greater silica skinpenetration extent into the deeper SC layers (about 42% and 18% silica following volar and dorsal forearmapplication, respectively) indicating that the NP surface polarity played a predominant role on that oftheir size in determining the route and the extent of penetration.
In vivo penetration of bare and lipid-coated silica nanoparticles across the human stratum corneum.
SCALIA, Santo;
2014
Abstract
Skin penetration of silica nanoparticles (NP) currently used in pharmaceutical and cosmetic products is atopic of interest not only to evaluate their possible toxicity, but also to understand their behaviour uponcontact with the skin and to exploit their potential positive effects in drug or cosmetic delivery field.Therefore, the present work aimed to elucidate the in vivo mechanism by which amorphous hydrophilicsilica NP enter human stratum corneum (SC) through the evaluation of the role played by the nanoparticlesurface polarity and the human hair follicle density. Two silica samples, bare hydrophilic silica (B-silica,162 ± 51 nm in size) and hydrophobic lipid-coated silica (LC-silica, 363 ± 74 nm in size) were appliedon both the volar and dorsal side of volunteer forearms. Twelve repetitive stripped tapes were removedfrom the human skin and evaluated for elemental composition by Energy Dispersive X-ray (EDX) analysisand for silicon content by Inductively Coupled Plasma quadrupole Mass Spectrometry (ICP-MS). All thestripped tapes revealed nanosized structures generally located in the broad spaces between corneocytesand characterized by the same elemental composition (relative weight percentage of silicon and siliconto oxygen weight ratio) than that of the applied samples. However, only about 10% B-silica permeateduntil the deepest SC layers considered in the study indicating a silica retention in the upper layers ofSC, regardless of the hair follicle density. Otherwise, the exposure to LC-silica led to a greater silica skinpenetration extent into the deeper SC layers (about 42% and 18% silica following volar and dorsal forearmapplication, respectively) indicating that the NP surface polarity played a predominant role on that oftheir size in determining the route and the extent of penetration.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
