title: Enhanced detection with spectral imaging fluorescence microscopy reveals tissue- and cell-type-specific compartmentalization of surface-modified polystyrene nanoparticles.
abstract: BACKGROUND
  Precisely targeted nanoparticle delivery is critically important for therapeutic applications. However, our knowledge on how the distinct physical and chemical properties of nanoparticles determine tissue penetration through physiological barriers, accumulation in specific cells and tissues, and clearance from selected organs has remained rather limited. In the recent study, spectral imaging fluorescence microscopy was exploited for precise and rapid monitoring of tissue- and cell-type-specific distribution of fluorescent polystyrene nanoparticles with chemically distinct surface compositions.
  
  
  METHODS
  Fluorescent polystyrene nanoparticles with 50-90 nm diameter and with carboxylated- or polyethylene glycol-modified (PEGylated) surfaces were delivered into adult male and pregnant female mice with a single intravenous injection. The precise anatomical distribution of the particles was investigated by confocal microscopy after a short-term (5 min) or long-term (4 days) distribution period. In order to distinguish particle-fluorescence from tissue autofluorescence and to enhance the detection-efficiency, fluorescence spectral detection was applied during image acquisition and a post hoc full spectrum analysis was performed on the final images.
  
  
  RESULTS
  Spectral imaging fluorescence microscopy allowed distinguishing particle-fluorescence from tissue-fluorescence in all examined organs (brain, kidney, liver, spleen and placenta) in NP-treated slice preparations. In short-time distribution following in vivo NP-administration, all organs contained carboxylated-nanoparticles, while PEGylated-nanoparticles were not detected in the brain and the placenta. Importantly, nanoparticles were not found in any embryonic tissues or in the barrier-protected brain parenchyma. Four days after the administration, particles were completely cleared from both the brain and the placenta, while PEGylated-, but not carboxylated-nanoparticles, were stuck in the kidney glomerular interstitium. In the spleen, macrophages accumulated large amount of carboxylated and PEGylated nanoparticles, with detectable redistribution from the marginal zone to the white pulp during the 4-day survival period.
  
  
  CONCLUSIONS
  Spectral imaging fluorescence microscopy allowed detecting the tissue- and cell-type-specific accumulation and barrier-penetration of polystyrene nanoparticles with equal size but chemically distinct surfaces. The data revealed that polystyrene nanoparticles are retained by the reticuloendothelial system regardless of surface functionalization. Taken together with the increasing production and use of nanoparticles, the results highlight the necessity of long-term distribution studies to estimate the potential health-risks implanted by tissue-specific nanoparticle accumulation and clearance.
authors.affiliation: School of PhD Studies, Semmelweis University, Üllői Street 26, Budapest, 1085, Hungary. kenesei.kata@koki.mta.hu.|Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony Street 43, Budapest, 1083, Hungary. kenesei.kata@koki.mta.hu.
authors.forename: Kata
authors.identifier: http://orcid.org/0000-0001-5711-885X
authors.initials: K
authors.lastname: Kenesei
authors.affiliation: School of PhD Studies, Semmelweis University, Üllői Street 26, Budapest, 1085, Hungary.|Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony Street 43, Budapest, 1083, Hungary.
authors.forename: Kumarasamy
authors.initials: K
authors.lastname: Murali
authors.affiliation: Soft Flow Hungary Kft., Kedves u. 20, Pecs, 7628, Hungary.
authors.forename: Árpád
authors.initials: Á
authors.lastname: Czéh
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Piella
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Victor
authors.initials: V
authors.lastname: Puntes
authors.affiliation: Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony Street 43, Budapest, 1083, Hungary.
authors.forename: Emília
authors.initials: E
authors.lastname: Madarász
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002451:Cell Compartmentation / Q000502:physiology; D004622:Embryo, Mammalian; D005260:Female; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism*; D061848:Optical Imaging / Q000295:instrumentation / Q000379:methods*; D009928:Organ Specificity; D010316:Particle Size; D010920:Placenta / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry / Q000493:pharmacokinetics*; D011247:Pregnancy; D013154:Spleen / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D011137:Polystyrenes; D011092:Polyethylene Glycols
keywords: In vivo distribution; Macrophage; Nanoparticle surface; Polystyrene nanoparticle; Spectral imaging fluorescence microscopy; Toxicity