Targeting and detecting cancer cells using spontaneously formed multifunctional dendrimer-stabilized gold nanoparticles.

We develop a facile approach to fabricating multifunctional dendrimer-stabilized gold nanoparticles (Au DSNPs) for cancer cell targeting and imaging. In this work, amine-terminated generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers pre-functionalized with folic acid (FA) and fluorescein isothiocyanate (FI) are complexed with Au(III) ions, followed by acetylation of the amine groups on the dendrimer surfaces. This one-step process leads to the spontaneous formation of 6 nm-sized Au nanoparticles stabilized by multifunctional dendrimers bearing both targeting and imaging functionalities. The multifunctional Au DSNPs are characterized by UV-Vis spectrometry, 1H NMR, and transmission electron microscopy (TEM). The formed Au DSNPs are water-soluble, stable, and biocompatible. Combined flow cytometry, confocal microscopy, silver staining, and inductively coupled plasma-mass spectrometry (ICP-MS) analyses show that the FA- and FI-functionalized Au DSNPs can specifically target to cancer cells expressing high-affinity FA receptors in vitro. This approach to functionalizing Au DSNPs may be extended to other targeting molecules, providing a unique nanoplatform for targeting and imaging of a variety of biological systems.