Biomimetic modification of silica nanoparticles for highly sensitive and ultrafast detection of DNA and Ag+ ions

Highly sensitive and selective detection of specific DNA or metal ions based on sensor platform of dye-labeled single-stranded DNA (named as ssDNA) and functional materials has attracted great research interest over the past few decades. Herein, we reported for the first time that polydopamine (PDA) modified SiO2 nanoparticles (PDA-co-SiO2 NPs) could be severed as effective fluorescent quenchers for fabrication of fluorescent DNA sensor systems for detection of functional nuclear acids and Ag+. To prepare PDA-co-SiO2 NPs, we just need mix SiO2 nanoparticles with dopamine in aqueous solution under rather mild experimental conditions. These PDA-co-SiO2 NPs-based sensor systems possess excellent sensitivity and selectivity, fast response for detection of target ssDNA and Ag+ based on different fluorescence quenching effect of PDA-co-SiO2 NPs towards ssDNA and dsDNA. Furthermore, the high fluorescence quenching ability of PDA-co-SiO2 NPs allows quantitative detection of target ssDNA with a low detection limit of 1 nM. More importantly, this method would also be easily extended for preparation of many other PDA-based materials for fabrication of fluorescent DNA sensors owing to the universal attachment of PDA with various materials and surfaces. Therefore, this work will open up a new direction for analytical detection of PDA-based functional materials.