Magnetic Bead-Based Multiplex DNA Sequence Detection of Genetically Modified Organisms Using Quantum Dot-Encoded Silicon Dioxide Nanoparticles

In this study, we report the multiplex DNA detection of genetically modified organisms (GMOs) based on fluorescence and magnetic nanostructures built up with quantum dot-encoded silicon dioxide nanoparticles (QD-encoded SiO2 NPs) and magnetic nanoparticles (MNPs). Detection was achieved by fluorescence spectrophotometry without auxiliary instruments. GMOs, including corn, soybean, colza, and cotton, were simultaneously detected, and the quantitative detection of soybean with a limit of detection of low femtomolar concentrations was successfully achieved. SiO2 NPs were encoded by different colored QDs at various ratios through a reverse microemulsion. QD-encoded SiO2 NP-labeled probe DNAs and MNP-labeled capture DNAs were used to hybridize with the corresponding targets at the same time. After magnetic separation, the sandwich structures were measured by fluorescence spectrophotometry. According to the overlay spectra of QDs, we estimated the presence of corresponding targets by analyzing the results via X-ray photoelectron spectroscopy peak software. Multiplex label-free DNA detection of GMOs based on QD-encoded SiO2 NPs showed high sensitivity and can be applied in other samples.