A sensitive optical sensor based on DNA-labelled Si@SiO2 core-shell nanoparticle for the detection of Hg2+ ions in environmental water samples

摘要

Si@SiO2 core-shell nanoparticles were proposed for the development of fluorescent mercury sensor, which also offers a promising alternative to toxic quantum dots (QD)-based heavy metal detection tools. In this study, a sensitive fluorescent assay based on DNA-labelled Si@SiO2 core-shell nanoparticles for the detection of mercury (II) in environmental samples was investigated. Probe DNA was conjugated on the surface of the Si@SiO2 core-shell nanoparticles via 5'-terminal-SH (thiol group) reaction. The detection protocol was based on the DNA hybridization resulted from the formation of mercury-mediated (thymine-Hg2+-thymine) base pairs which leave a fluorescent QD on the surface of quartz glass. The synthesized Si@SiO2 core-shell nanoparticle showed a broad emission peak with strong intensity in the UV range around 423 nm. Transmission electronic microscope (TEM) images confirmed the presence of a uniform core-shell structure with Si core nanoparticles with a particle size ranging from 70 to 80 nm and silica shell thickness of about 10 +/- 2 nm. Overall, our findings highlighted that the developed assay can detect Hg2+ ions in aqueous solution as low as 0.92 nM concentration. In addition, the labelled Si@SiO2 core-shell nanoparticles showed prominence sensitivity, acceptable precision, reproducibility and stability, and could be readily applied to environmental sampling systems for Hg2+ monitoring.