Penetration of Gold Nanoparticles Across the Stratum Corneum Layer of Thick-Skin

A major hurdle for transdermal drug delivery, is the passage of drugs across the stratum corneum (SC) layer of the epidermis. The SC comprises of thick keratinized epithelium that blocks entry of most hydrophobic and hydrophilic drugs [1]. Of special interest is the skin over the palmar and plantar areas, where the overall thickness of skin, along with the SC is much higher than other anatomical sites [2,3]. Further, the epidermis in the plantar and palmar areas is 3–4 fold thicker, thus making topical drug absorption highly dependent on the site of application [4].