Electrochemical genoassays on gold-coated magnetic nanoparticles to quantify genetically modified organisms (GMOs) in food and feed as GMO percentage

• Published in: Biosensors & bioelectronics Vol. 110; pp. 147 - 154
• Main Authors: Plácido, Alexandra, Pereira, Clara, Guedes, Alexandra, Barroso, M. Fátima, Miranda-Castro, Rebeca, de-los-Santos-Álvarez, Noemí, Delerue-Matos, Cristina
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.07.2018
• Subjects: Biosensing Techniques - methods; Core-shell Fe3O4@Au magnetic nanoparticles; DNA, Plant - genetics; Electrochemical genoassay; Electrochemical Techniques - methods; Genetically modified soybean; Glycine max - genetics; GMO quantification; Gold - chemistry; GTS 40-3-2; Magnetite Nanoparticles - chemistry; Magnetite Nanoparticles - ultrastructure; Nucleic Acid Hybridization; Plants, Genetically Modified - genetics; GTS 40-3-2; Electrochemical genoassay; Genetically modified soybean; GMO quantification; Core-shell Fe3O4@Au magnetic nanoparticles; Core-shell FeO@Au magnetic nanoparticles
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2018.03.042

The integration of nanomaterials in the field of (bio)sensors has allowed developing strategies with improved analytical performance. In this work, ultrasmall core-shell Fe3O4@Au magnetic nanoparticles (MNPs) were used as the platform for the immobilization of event-specific Roundup Ready (RR) soybean and taxon-specific DNA sequences. Firstly, monodisperse Fe3O4 MNPs were synthesized by thermal decomposition and subsequently coated with a gold shell through reduction of Au(III) precursor on the surface of the MNPs in the presence of an organic capping agent. This nanosupport exhibited high colloidal stability, average particle size of 10.2 ± 1.3 nm, and spherical shape. The covalent immobilization of ssDNA probe onto the Au shell of the Fe3O4@Au MNPs was achieved through a self-assembled monolayer (SAM) created from mixtures of alkane thiols (6-mercapto-1-hexanol and mercaptohexanoic acid). The influence of the thiols ratio on the electrochemical performance of the resulting electrochemical genoassays was studied, and remarkably, the best analytical performance was achieved for a pure mercaptohexanoic acid SAM. Two quantification assays were designed; one targeting an RR sequence and a second targeting a reference soybean gene, both with a sandwich format for hybridization, signaling probes labelled with fluorescein isothiocyanate (FITC), enzymatic amplification and chronoamperometric detection at screen-printed carbon electrodes (SPCE). The magnetogenoassays exhibited linear ranges from 0.1 to 10.0 nM and from 0.1 to 5.0 nM with similar detection limits of 0.02 nM and 0.05 nM for the event-specific (RR) and the taxon-specific (lectin) targets, respectively. The usefulness of the approach was demonstrated by its application to detect genetically modified organisms (GMOs) in feed and food. •Core-shell Fe3O4@Au magnetic nanoparticles as a platform for two hybridization based assays.•Controlled synthesis yielded monodisperse and highly stable magnetic nanoparticles.•Pure mercaptohexanoic acid SAM needed no blocking agents.•Genoassays for soybean GTS 40-3-2 event and lectin gene were designed with subnM limit of detections.•Seed and feed samples quantified as GMO percentage accordingly to legislation.