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 SiO 2 nanoparticles (PDA- co -SiO 2 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 -SiO 2 NPs, we just need mix SiO 2 nanoparticles with dopamine in aqueous solution under rather mild experimental conditions. These PDA- co -SiO 2 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 -SiO 2 NPs towards ssDNA and dsDNA. Furthermore, the high fluorescence quenching ability of PDA- co -SiO 2 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.