title: Influence of surface charge of gold nanorods on skin penetration.
abstract: OBJECTIVE
  The skin plays an important role as a protective barrier against toxic environments and also is a route of drug administration. In spite of evidence for and interest in the skin penetration of nanoparticles, no study has examined the effect of nanoparticle surface charge on percutaneous absorption. In this study, we investigated the effect of surface charges of gold nanorods (GNs) on skin penetration.
  
  
  METHODS
  Using transmission electron microscopy (TEM) and image analysis, we quantitatively measured the ability of GNs to penetrate the skin.
  
  
  RESULTS
  Our results showed that the area density of the electron-dense dots of GNs, which penetrated into the stratum corneum, significantly increased for negatively charged GNs compared to those with a positive charge (P < 0.01). To investigate the percutanoues absorption of charged GNs, in vitro skin permeation studies were carried out using a Franz-type diffusion cell (FDC). The penetration of GNs through the skin was quantified by inductively coupled plasma mass spectrometry. Consistent with TEM observations, our penetration study using an FDC also revealed that negative particles were frequently detected in samples of receptor fluid at 48 h after exposure (P < 0.01).
  
  
  CONCLUSIONS
  Together our results showed that anionic GNs penetrate skin better than cationic GNs.
authors.affiliation: Department of Radiological Science, College of Natural Science, Gimcheon University, Gimcheon City, Gyeangbuk, Korea.
authors.forename: Onseok
authors.initials: O
authors.lastname: Lee
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Jeong
authors.forename: Won Ung
authors.initials: WU
authors.lastname: Shin
authors.forename: Gunwoo
authors.initials: G
authors.lastname: Lee
authors.forename: Chilhwan
authors.initials: C
authors.lastname: Oh
authors.forename: Sang Wook
authors.initials: SW
authors.lastname: Son
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D000838:Anions / Q000737:chemistry / Q000493:pharmacokinetics; D002412:Cations / Q000737:chemistry / Q000493:pharmacokinetics; D004058:Diffusion; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D006046:Gold / Q000737:chemistry / Q000493:pharmacokinetics*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D008812:Mice, Hairless; D046529:Microscopy, Electron, Transmission; D043942:Nanotubes / Q000737:chemistry*; D012869:Skin Absorption / Q000187:drug effects* / Q000502:physiology*; D013499:Surface Properties
chemical_list: D000838:Anions; D002412:Cations; D006046:Gold