Highly Monodisperse Fe3O4@Au Superparamagnetic Nanoparticles as Reproducible Platform for Genosensing Genetically Modified Organisms

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• 作者：Maria Freitas ; Maria Sá Couto ; Maria Fátima Barroso ; Clara Pereira ; Noemí de-los-Santos-Álvarez ; Arturo J. Miranda-Ordieres ; María Jesús Lobo-Castañón ; Cristina Delerue-Matos
• 刊名：ACS Sensor
• 出版年：2016
• 出版时间：August 26, 2016
• 年：2016
• 卷：1
• 期：8
• 页码：1044-1053
• 全文大小：688K
• ISSN：2379-3694

文摘

Several routes have been developed to prepare magnetic core–shell Fe₃O₄@Au nanoparticles (MNPs). However, only highly monodisperse MNPs are suitable for analytical applications. Herein, we describe the detection of GMO through the use of gold-coated MNPs with fine-tuned properties as platforms. The MNPs were prepared through a procedure that involves the preparation of Fe₃O₄ cores by thermal decomposition and their coating through reduction of a gold precursor. Different Fe₃O₄:Au precursor molar ratios (1:1; 1:4; 1:7) were tested on the Fe₃O₄ encapsulation. Monodisperse quasi-spherical core–shell Fe₃O₄@Au were obtained for the 1:4 and 1:7 ratios, in contrast, the 1:1 ratio did not lead to complete encapsulation of Fe₃O₄ cores. Therefore, the Fe₃O₄@Au obtained from higher Fe₃O₄:HAuCl₄ ratios were tested as platforms for an electrochemical genoassay to detect MON810. The best performance was achieved with the Fe₃O₄@Au prepared from 1:4 ratio (10.0 ± 1.7 nm). A DNA probe covalently linked to a carboxylated self-assembled monolayer and a fluorescein isothiocyanate (FITC) signaling probe were used in a sandwich assay format. Labeling with anti-FITC-peroxidase Fab fragment conjugate allowed chronoamperometric measurements of the enzyme activity captured on Fe₃O₄@Au placed on screen-printed electrodes upon the hybridization event. The genoassay provided a linear range from 0.25 to 2.5 nM, LOD of 0.15 nM, with a reproducibility <4%. Certified samples containing the transgenic event were measured without further purification after PCR amplification. The results highlight the efficiency of the genoassay for the MON810 detection, opening new horizons to achieve a low-cost analysis out of large laboratory facilities to verify the compliance of GMO regulations.