title: Fluorescence imaging of APP in Alzheimer's disease with quantum dot or Cy3: a comparative study.
abstract: OBJECTIVE
  To compare the fluorescence intensity and duration of qdots streptavidin conjugate (QDs-SA) with Cy3 as the molecular probe of β-amyloid precursor protein (APP), and to provide evidence for early molecular imaging and diagnosis of Alzheimer's disease (AD).
  
  
  METHODS
  With the help of laser scanning confocal microscope and flow cytometry, the flurescence probe based on the QDs-SA was used to detect APP in HEK293 cells stably transfected pcDNA3.1/APP, and to compare with conventional fluroimmunoassay Cy3.
  
  
  RESULTS
  The immunofluorescence staining detection indicated APP expression was mainly located in the plasma membrane. The mean fluorescence intensity of QDs-SA (34.2336±4.2455) was greater than that of Cy3 (21.6023±3.0102)under the confocal fluorescence microscope (P<0.05). After persistent exciting for 12 min, the fluorescence intensity of APP stained by QDs-SA decreased by 27.87%. The other stained by Cy3 decreased by 79.60%. The positive rate of APP staining had no significant difference between the QDs-SA(54.4700±3.4433)% and Cy3 (54.3800±8.5229)% by flow cytometry, but the mean fluorescence intensity had statistical significance(P<0.05). The QDs-SA (1 045.4167±47.3623) was significantly higher than the mean fluorescence intensity of Cy3 (658.5467±55.0591).
  
  
  CONCLUSIONS
  QDs-SA fluorescence probes can effectively recognize APP and are sensitive and exceptionally photostable, suggesting that QDs-SA fluorescence probes could be a potential method in APP detection and offer a novel way for the diagnosis of Alzheimer's disease.
authors.affiliation: Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Li
authors.initials: L
authors.lastname: Feng
authors.forename: Shuyu
authors.initials: S
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Xiao
authors.forename: Si
authors.initials: S
authors.lastname: Chen
authors.forename: Renkai
authors.initials: R
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000544:Alzheimer Disease / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism*; D002232:Carbocyanines; D005456:Fluorescent Dyes; D018014:Gene Transfer Techniques; D057809:HEK293 Cells; D006801:Humans; D057054:Molecular Imaging; D045663:Quantum Dots
chemical_list: C545487:APP protein, human; D016564:Amyloid beta-Protein Precursor; D002232:Carbocyanines; D005456:Fluorescent Dyes; C089187:cyanine dye 3