Size-Dependent Cellular Uptake of Trans-Activator of Transcription Functionalized Nanoparticles.

We investigated the cellular uptake efficiencies of differently-sized silica nanoparticles in the presence and the absence of trans-activator of transcription (TAT) peptide. Silica nanoparticles incorporating fluorescent dye molecules with diameters of 30 to 800 nm were synthesized, and the surfaces of the silica nanoparticles were functionalized with TAT peptides or 3-aminopropyltriethoxysilane (APTES). Confocal microscopy and flow cytometry were used to determine the cellular locations and the uptake efficiencies of positively-charged silica nanoparticles (APTES- and TAT-) of various sizes from 30 to 800 nm. The cellular uptake efficiencies of all the differently-sized particles were significantly increased in the presence of TAT peptides. On the basis of an efficient TAT-mediated delivery system, we were able to show that TAT peptides could be used as effective cellular-uptake reagents, particularly for large particles.