Received on May 15, 2007
Accepted on October 2, 2007

Automation and Analytical Techniques

Visual Recognition and Efficient Isolation of Apoptotic Cells with Fluorescent-Magnetic-Biotargeting Multifunctional Nanospheres

¹ College of Chemistry and Molecular Sciences and State Key Laboratory of Virology, Wuhan University, Wuhan, Peoples Republic of China
² School of Life Science and Technology, Beijing Institute of Technology, Beijing, Peoples Republic of China
³ School of Life Science and Technology, Xi'an Jiaotong University, Peoples Republic of China
⁴ Section on Molecular Morphogenesis, Program on Cell Regulation and Metabolism, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD

^* To whom correspondence should be addressed. E-mail: dwpang{at}whu.edu.cn.

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.