Gold nanoparticles capped by a GC-containing peptide functionalized with an RGD motif for integrin targeting.

Gold nanoparticles were obtained by reduction of a tetrachloroaurate aqueous solution in the presence of a RGD-(GC)2 peptide as stabilizer. As comparison, the behavior of the (GC)2 peptide has been studied. The (GC)2 and RGD-(GC)2 peptides were prepared ad hoc by Fmoc synthesis. The colloidal systems have been characterized by UV–visible, TGA, ATR-FTIR, mono and bidimensional NMR techniques, confocal and transmission (TEM) microscopy, ζ-potential, and light scattering measurements. The efficient cellular uptake of Au-RGD-(GC)2 and Au-(GC)2 stabilized gold nanoparticles into U87 cells (human glioblastoma cells) were investigated by confocal microscopy and compared with the behavior of (GC)2 capped gold nanoparticles. A quantitative determination of the nanoparticles taken up has been carried out by measuring the pixel brightness of the images, a measure that highlighted the importance of the RGD termination of the peptide. Insight in the cellular uptake mechanism was investigated by TEM microscopy. Various...