Facile synthesis of fluorescent Au@SiO2 nanocomposites for application in cellular imaging

A novel fluorescent Au@SiO2 nanocomposite, with average size of ca. 30 nm in the diameter, was prepared via a simple microemulsion method. Additionally, transmission electron microscopy (TEM), UV-Vis absorption spectra, Fourier transform infrared (FT-IR) spectra and fluorescence spectra were used to characterize this nanocomposite. This newly synthesized, silica-wrapped, gold nanocluster has the following advantages: good water solubility, exceptional biocompatibility, favorable surface properties and excellent fluorescence properties. Because of these advantages, a Au@SiO2 nanocomposite is exceptionally suitable for biological applications. In this study, cellular imaging, as a form of biological application, has been fully investigated, and it was discovered, after covalent conjugation of folic acid (FA), that the nanocomposite effectively recognized over expressed folic acid receptors (FARs) on the HeLa cell's surface. Therefore, this fluorescent Au@SiO2 nanocomposite could be used as a new fluorescent probe for selective biological imaging. (C) 2011 Elsevier BM. All rights reserved.