An Annexin V-based biosensor for quantitatively detecting early apoptotic cells

In this paper, we reported that a novel biosensor was developed to detect early apoptotic cells by the specific interaction between Annexin V and phosphatidylserine based on electrochemical impedance. Annexin V was immobilized on a self-assembled layer of gold nanoparticles, which allowed stable and high loading of Annexin V on the electrode surface, offering the possibility of sensitivity enhancement. Early apoptotic cells showed an increased exposition of phosphatidylserine on the cell membrane caused by physiological and pathological response reaction, leading to a strong interaction between the apoptotic cells and the electrode surface, which could be probed by electrochemical impedance spectroscopy. As examined using a model system of cells integrated by phosphatidylserine-modified liposome and a real one of early apoptotic cell induced by 5-fluorouracil, this biosensor demonstrated the great potential for rapid detection of cell apoptosis and drug screening. The results agreed well with those obtained using fluorescence microscopy and flow cytometry. (C) 2008 Published by Elsevier B.V.