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Proceedings Paper

Toxoplasma gondii DNA detection with a magnetic molecular beacon probe
Author(s): Shichao Xu; Cuicui Yao; Shuoming Wei; Jimei Zhang; Zhao Dai; Guo Zheng; Bo Sun; Qing Han; Fei Hu; Hongming Zhou
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Paper Abstract

Toxoplasma Gondii infection is widespread in humans worldwide and reported infection rates range from 3%-70%, depending on the populations or geographic areas, and it has been recognized as a potential food safety hazard in our daily life. A magnetic molecular beacon probe (mMBP), based on theory of fluorescence resonance energy transfer (FRET), was currently reported to detect Toxoplasma Gondii DNA. Nano-sized Fe3O4 were primarily prepared by coprecipitation method in aqueous phase with NaOH as precipitator, and was used as magnetic core. The qualified coreshell magnetic quantum dots (mQDs), i.e. CdTe(symbol)Fe3O4, were then achieved by layer-by-layer method when mol ratio of Fe3O4/CdTe is 1/3, pH at 6.0, 30 °C, and reactant solution was refluxed for 30 min, the size of mQDs were determined to be 12-15 nm via transmission electron microscopy (TEM). Over 70% overlap between emission spectrum of mQDs and absorbance spectrum of BHQ-2 was observed, this result suggests the synthesized mQDs and BHQ-2 can be utilized as energy donor and energy acceptor, respectively. The sensing probe was fabricated and a stem-loop Toxoplasma Gondii DNA oligonucleotide was labeled with mQDs at the 5' end and BHQ-2 at 3' end, respectively. Target Toxoplasma gondii DNA was detected under conditions of 37 °C, hybridization for 2h, at pH8.0 in Tris-HCl buffer. About 30% recovery of fluorescence intensity was observed via fluorescence spectrum (FS) after the Toxoplasma gondii DNA was added, which suggested that the Toxoplasma Gondii DNA was successfully detected. Specificity investigation of the mMBP indicated that relative low recovery of fluorescence intensity was obtained when the target DNA with one-base pair mismatch was added, this result indicated the high specificity of the sensing probe. Our research simultaneously indicated that mMBP can be conveniently separated from the unhybridized stem-loop DNA and target DNA, which will be meaningful in DNA sensing and purification process.

Paper Details

Date Published: 2 February 2009
PDF: 5 pages
Proc. SPIE 7157, 2008 International Conference on Optical Instruments and Technology: Advanced Sensor Technologies and Applications, 715710 (2 February 2009); doi: 10.1117/12.806932
Show Author Affiliations
Shichao Xu, Tianjin Polytechnic Univ. (China)
Cuicui Yao, Tianjin Polytechnic Univ. (China)
Shuoming Wei, Heilongjiang Univ. (China)
Jimei Zhang, Tianjin Polytechnic Univ. (China)
Zhao Dai, Tianjin Polytechnic Univ. (China)
Guo Zheng, Tianjin Polytechnic Univ. (China)
Bo Sun, Nankai Univ. (China)
Qing Han, Tianjin Polytechnic Univ. (China)
Fei Hu, Tianjin Polytechnic Univ. (China)
Hongming Zhou, Tianjin Polytechnic Univ. (China)

Published in SPIE Proceedings Vol. 7157:
2008 International Conference on Optical Instruments and Technology: Advanced Sensor Technologies and Applications
Anbo Wang; YanBiao Liao; AiGuo Song; Yukihiro Ishii; Xudong Fan, Editor(s)

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