title: Gold nanoparticle penetration and reduced metabolism in human skin by toluene.
abstract: OBJECTIVE
  To measure penetration and metabolic effects of ion-stabilized, polar, 15 nm gold nanoparticles in aqueous solution (AuNP-Aq) and sterically stabilized, non-polar, 6 nm gold nanoparticles in toluene (AuNP-TOL) on excised human skin.
  
  
  METHODS
  Gold nanoparticles were characterized with dynamic light scattering and transmission electron microscopy (TEM). Skin penetration studies were done on frozen or fresh excised skin using static Franz diffusion cells. Viable treated skin was assessed by dermoscopy, reflectance confocal microscopy (RCM), multiphoton tomography (MPT) with fluorescence lifetime imaging microscopy (FLIM), and TEM.
  
  
  RESULTS
  Dermoscopy and RCM showed large aggregates in the furrows of AuNP-Aq-treated skin. Treatment of thawed and viable skin only showed enhanced permeability to nanoparticles in the AuNP-TOL group with MPT and FLIM imaging to stratum spinosum of epidermis. TEM analysis revealed gold nanoparticles within AuNP-treated stratum corneum. FLIM analysis of NAD(P)H showed a significant decrease in total NAD(P)H in all toluene-treated groups.
  
  
  CONCLUSIONS
  Gold nanoparticles, 15 nm, in aqueous solution aggregated on the skin surface. Toluene treatment eliminated skin metabolism; skin treated with toluene/gold nanoparticles (6 nm) for 24 h, but not at 4 h, showed increased nanoparticle permeability. These results are of value to nanotoxicology.
authors.affiliation: Department of Pharmaceutical Nanotechnology, Saarland University, Saarbrücken, Germany.
authors.forename: Hagar I
authors.initials: HI
authors.lastname: Labouta
authors.forename: David C
authors.initials: DC
authors.lastname: Liu
authors.forename: Lynlee L
authors.initials: LL
authors.lastname: Lin
authors.forename: Margaret K
authors.initials: MK
authors.lastname: Butler
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Grice
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Raphael
authors.forename: Tobias
authors.initials: T
authors.lastname: Kraus
authors.forename: Labiba K
authors.initials: LK
authors.lastname: El-Khordagui
authors.forename: H Peter
authors.initials: HP
authors.lastname: Soyer
authors.forename: Michael S
authors.initials: MS
authors.lastname: Roberts
authors.forename: Marc
authors.initials: M
authors.lastname: Schneider
authors.forename: Tarl W
authors.initials: TW
authors.lastname: Prow
mesh_terms: D000279:Administration, Cutaneous; D004339:Drug Compounding; D016503:Drug Delivery Systems; D004353:Drug Evaluation, Preclinical; D004817:Epidermis / Q000378:metabolism; D006046:Gold / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry*; D009249:NADP / Q000032:analysis / Q000378:metabolism; D010316:Particle Size; D010539:Permeability; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D012997:Solvents / Q000378:metabolism*; D014050:Toluene / Q000378:metabolism*
chemical_list: D012997:Solvents; D014050:Toluene; D009249:NADP; D006046:Gold