DETECTION OF CANDIDATUS PHYTOPLASMA AURANTIFOLIA WITH A QUANTUM DOTS FRET-BASED BIOSENSOR

F. Rad, A. Mohsenifar, M. Tabatabaei, M.R. Safarnejad, F. Shahryari, H. Safarpour, A. Foroutan, M. Mardi, D. Davoudi, M. Fotokian

Abstract


The witches’ broom disease of lime (WBDL) supposedly caused by Candidatus Phytoplasma aurantifolia (Ca. P. aurantifolia) is the most devastating disease of lime in Oman and southern parts of Iran. The present study describes developing a quantum dot (QD)-based nano-biosensor for the highly sensitive detection of phytoplasma in infected trees. The immunodominant membrane protein (IMP) expressed in the surface of phytoplasma was selected as a target protein for construction of a specific binding antibody. The antibody (anti-IMP) was effectively conjugated to tioglicolic acid-modified cadmium-telluride quantum dots (CdTe-QDs) synthesized in an aqueous solution via electrostatic interaction. Dye (rhodamine) molecules were attached to the IMP, then, the donor-acceptor complexes (QDs-Ab-IMPRhodamine) were formed based on the antigen-antibody interaction. The mutual affinity of the antigen and the antibody brought the CdTe QDs and rhodamine together close enough to allow the fluorescence resonance energy transfer (FRET) to occur. The immunosensor constructed showed a high sensitivity and specificity of 100%, a detection limit of 5 ca. P. aurantifolia/µl, and acceptable stability, so it could be used for detection with consistent results.

Keywords


biosensing; detection;Candidatus Phytoplasma aurantifolia;quantum dots (QDs);FRET;immunodominant membrane protein (IMP)

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DOI: http://dx.doi.org/10.4454/JPP.FA.2012.054

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