Previous studies have shown that functionalized gold nanoparticles (AuNPs) can be used as a general platform for loading and delivering DNA oligonucleotides and short hairpin RNA to living systems. Here, we report the ability of functionalized AuNP to deliver RNA aptamers into the nuclei of human cells. An in vitro-synthesized RNA aptamer specific to the p-catenin protein was delivered into the HepG2 human cell line more efficiently via functionalized AuNP than liposome-based delivery, and resulted in nearly complete inhibition of beta-catenin binding to the p50 subunit of NF-kappa beta in the nucleus. This inhibition led to repression of NF-kappa beta p50-dependent transcription of CRP. Also, the p-catenin aptamer in the nucleus led to down-regulation of p-catenin-mediated transcriptional activity through the TCF complex and resulted in decrease in the levels of cyclin D, and c-myc mRNA by similar to 47% and similar to 57%, respectively. In addition, we used functionalized AuNP to deliver another RNA aptamer targeted to the p50 subunit of NF-kappa B into the A549 human cell line, and this was sufficient to induce apoptosis of the cells. Our findings demonstrate that AuNP GDS can be used to deliver small, highly structured RNA aptamers into the nucleus of human cells where they modulate the activity of transactivators by interacting with target proteins. (C) 2011 Elsevier Inc. All rights reserved.