Preparation Of Silica-Shell Fluorescent Nanoparticles And Their Applications In Chemo/Biosensing

Fluorescence analytical technologies have various distinguished advantages including high sensitivity, good selectivity, easy operation, and so on, thus they are broadly used in building chemical/biological sensing system. Fluorescence reagents have some insurmountable drawbacks such as photobleaching, unstable fluorescence signal, which restrict wider application of fluoremetry. In this thesis, we prepared silica-shell fluorescent nanoparticles which use silica as shell and fluophores as core, possess some distinct advantages, such as good monodisperse, anti-photobleaching and so on. Based on these distinct characteristics, we prepared the chemosensor for pH and a biosensor for DNA hybridization detection. The details are summarized as follows:1. With the water-in-oil reverse microemulsion method, we prepared a pH sensor near-neutral value(5.50⁸.99) based on fluorescent silica nanoparticles which use fluorescent dye, 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) as core and silica as shell. The properties of the present sensor were studied and the present pH sensor was used to monitor pH in real samples, and the results are in good agreement with data obtained with a glass electrode. 2. Aminated silica nanoparticles which use fluorescent dye, fluorescein isothiocyanate (FITC) as core and silica as shell were synthesized with reverse microemulsion method, and we prepared a biosensor for sequence-specific DNA detection, which is based on fluorescence resonance energy transfer (FRET) system with fluorescein isothiocyanate (FITC)-doped silica nanoparticles (SiNPs), as donor and Au nanoparticles (AuNPs) as acceptor. Under the optimal experimental conditions, the linear range of the sensor is 0-35 nM with the detection limit (3σ) is 3.0 picomole (3×10^-12 M).