title: Time-correlated single photon counting for simultaneous monitoring of zinc oxide nanoparticles and NAD(P)H in intact and barrier-disrupted volunteer skin.
abstract: OBJECTIVE
  There is a lack of relevant, non-animal alternatives for assessing exposure and toxicity of nanoparticle-containing cosmetics, e.g. sunscreens. Our goal was to evaluate timecorrelated single photon counting (TCSPC) for simultaneous monitoring of zinc oxide nanoparticles (ZnO-NP) and the metabolic state of volunteer skin.
  
  
  METHODS
  We separated the fluorescence lifetime signatures of endogenous fluorophore signals (i.e. nicotinamide adenine dinucleotide phosphate, NAD(P)H and keratin) and the ZnO-NP signal using advanced TCSPC to simultaneously determine ZnO-NP penetration profiles and NAD(P)H changes in subjects with altered barrier function, including tape-stripped skin and in psoriasis or atopic dermatitis lesions.
  
  
  RESULTS
  We detected no ZnO-NP penetration into viable human skin in any group. ZnO-NP signal was significantly increased (p < 0.01) on the surface of tape-stripped and lesional skin after 4 and 2 h of treatment, respectively. Free NAD(P)H signal significantly increased in tape-stripped viable epidermis treated for 4 h of ZnO-NP compared to vehicle control. No significant NAD(P)H changes were noted in the lesional study.
  
  
  CONCLUSIONS
  TCSPC techniques enabled simultaneous, real-time quantification of ZnO-NP concentration and NAD(P)H via non-invasive imaging in the stratum corneum and viable epidermis of volunteers.
authors: Therapeutics Research Centre, School of Medicine Princess Alexandra Hospital, University of Queensland, Brisbane, Queensland, Australia.
authors: Lynlee L
authors: LL
authors: Lin
authors: Jeffrey E
authors: JE
authors: Grice
authors: Margaret K
authors: MK
authors: Butler
authors: Andrei V
authors: AV
authors: Zvyagin
authors: Wolfgang
authors: W
authors: Becker
authors: Thomas A
authors: TA
authors: Robertson
authors: H Peter
authors: HP
authors: Soyer
authors: Michael S
authors: MS
authors: Roberts
authors: Tarl W
authors: TW
authors: Prow
mesh_terms: D000287:Administration, Topical; D003358:Cosmetics / Q000378:metabolism; D003876:Dermatitis, Atopic / Q000188:drug therapy / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D006801:Humans; D053768:Metal Nanoparticles / Q000008:administration & dosage / Q000032:analysis* / Q000627:therapeutic use; D009249:NADP / Q000032:analysis* / Q000378:metabolism; D017785:Photons; D011565:Psoriasis / Q000188:drug therapy / Q000378:metabolism*; D012867:Skin / Q000737:chemistry* / Q000378:metabolism; D012869:Skin Absorption; D013473:Sunscreening Agents / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism / Q000627:therapeutic use; D053832:Surgical Tape; D013997:Time Factors; D018675:Toxicity Tests / Q000379:methods; D014870:Water Loss, Insensible / Q000502:physiology; D015034:Zinc Oxide / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism* / Q000627:therapeutic use
chemical_list: D003358:Cosmetics; D013473:Sunscreening Agents; D009249:NADP; D015034:Zinc Oxide