Preparation of aminated core-shell fluorescent nanoparticles and their application to the synchronous fluorescence determination of γ-globulin

Amino-modified silica nanoparticles (FSNPs) doped with fluorescein isothiocyanate (FITC) were synthesized by using an aqueous core of reverse-micelle microemulsion as the nanoreactor in an easy one-pot method. Due to the FITC conjugating with (3-aminopropyl)triethoxysilane (APTS), the nanoparticles prevent the FITC from leaching from the silica matrix when immersed in aqueous solution. SEM, FTIR, fluorescence lifetime, a photobleaching experiment and synchronous fluorescence spectra were used to characterize the FSNPs. The synchronous fluorescence signal of FSNPs was enhanced when trace amounts of gamma-globulin (gamma-G) were added. Under the optimal experimental conditions, the enhanced fluorescence intensity (Delta F) was linear with the concentration of gamma-G (c) in the range 0.3-4.8 mu g/ml., with a detection limit of 0.04 mu g/mL. The proposed method is simple, sensitive for the determination of trace amounts of gamma-G and used to determine the content of gamma-G in synthetic samples with satisfactory results. Copyright (c) 2008 John Wiley & Sons, Ltd.