Abstract: A novel fluorescent core-shell nanoparticle has been developed by encapsulating the fluorophore into silica shell with a reverse microemulsion technique. The FITC encapsulation is greatly enhanced by conjucting a water-soluble protein IgG which significantly reduces FITC leaching from the nanoparticles when immersed inside water. The FITC leaching problem of the nanoparticles prepared with IgG has been much less severe than that with the FITC nanoparticles prepared with unmodified dye or dye modified with dextrans of higher molecular weight. The fluorescent core-shell nanoparticles are also pH sensible. They can be used as pH optical sensors inside cell phagocytosed by murine macrophages.

Key words: Water-in-oil microemulsion, Fluorescein isothiocyante(FITC), Immunoglobal(IgG), Fluorescent core-shell nanoparticles