title: Visual recognition and efficient isolation of apoptotic cells with fluorescent-magnetic-biotargeting multifunctional nanospheres.
abstract: BACKGROUND
  Fluorescent-magnetic-biotargeting multifunctional nanospheres are likely to find important applications in bioanalysis, biomedicine, and clinical diagnosis. We have been developing such multifunctional nanospheres for biomedical applications.
  
  
  METHODS
  We covalently coupled avidin onto the surfaces of fluorescent-magnetic bifunctional nanospheres to construct fluorescent-magnetic-biotargeting trifunctional nanospheres and analyzed the functionality and specificity of these trifunctional nanospheres for their ability to recognize and isolate apoptotic cells labeled with biotinylated annexin V, which recognizes phosphatidylserine exposed on the surfaces of apoptotic cells.
  
  
  RESULTS
  The multifunctional nanospheres can be used in combination with propidium iodide staining of nuclear DNA to identify cells at different phases of the apoptotic process. Furthermore, we demonstrate that apoptotic cells induced by exposure to ultraviolet light can be isolated simply with a magnet from living cells at an efficiency of at least 80%; these cells can then be easily visualized with a fluorescence microscope.
  
  
  CONCLUSIONS
  Our results show that fluorescent-magnetic-biotargeting trifunctional nanospheres can be a powerful tool for rapidly recognizing, magnetically enriching and sorting, and simultaneously identifying different kinds of cells.
authors.affiliation: College of Chemistry and Molecular Sciences and State Key Laboratory of Virology, Wuhan University, Wuhan, Peoples Republic of China.
authors.forename: Er-Qun
authors.initials: EQ
authors.lastname: Song
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Wang
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Xie
authors.forename: Zhi-Ling
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Jun
authors.initials: J
authors.lastname: Peng
authors.forename: Dao-Cheng
authors.initials: DC
authors.lastname: Wu
authors.forename: Yun-Bo
authors.initials: YB
authors.lastname: Shi
authors.forename: Dai-Wen
authors.initials: DW
authors.lastname: Pang
mesh_terms: D017304:Annexin A5; D017209:Apoptosis; D001360:Avidin; D001710:Biotin; D002469:Cell Separation / Q000379:methods*; D004396:Coloring Agents; D005290:Ferric Compounds; D005434:Flow Cytometry / Q000379:methods; D005456:Fluorescent Dyes; D006367:HeLa Cells; D006801:Humans; D008280:Magnetics; D054118:Nanospheres; D010718:Phosphatidylserines / Q000378:metabolism; D011419:Propidium; D045663:Quantum Dots
chemical_list: D017304:Annexin A5; D004396:Coloring Agents; D005290:Ferric Compounds; D005456:Fluorescent Dyes; D010718:Phosphatidylserines; D001360:Avidin; C000499:ferric oxide; D011419:Propidium; D001710:Biotin