Presentation day

Thursday  8:20 PM

TITLE

Intracellular delivery of fluorescent nanoparticles self-assembled from a cytidylic acid-appended
fluorescein dye

Abstract

The development of techniques for intracellular delivery of materials has attracted the
attention of many researchers owing to the potential application of these techniques in biomedical and
pharmaceutical uses. Particularly, the delivery of materials to the nucleus is considered an important
technique because that is where genetic information is stored; however, most nanomaterials reported so far
remain trapped in the cytoplasm after penetrating the cell membrane.
We studied the self-assembly of nucleotide-appended bolaamphiphiles, which are amphiphilic molecules
with a hydrophilic nucleotide moiety at each end of a long hydrophobic chain.1 In the present study, we
synthesized a cytidylic acid-appended fluorescent dye 1, and demonstrated that it spontaneously formed
fluorescent nanoparticles. We examined the cellular uptake of these nanoparticles into Caco-2 and
BALB/3T3 cells.
The synthesis of 1 and the preparation of the nanoparticles were carried out using a similar procedure as
reported previously.1, 2 Cells were cultured using a medium containing the nanoparticles formed from 1.
Flow cytometry and fluorescent microscopy demonstrated that the nanoparticles entered Caco-2 and
BALB/3T3 cells with efficiencies of 80% and 55%, respectively. We observed the accumulation of
fluorescence in the nuclei of Caco-2 cells after 7 days of culture, but not in the nuclei of BALB/3T3 cells.
The accumulation of fluorescence was observed mainly after the plateau phase of Caco-2 cell growth,
indicating that 1 permeated the nuclear envelope without nuclear-localizing signal tags in a cell dependent
manner. We hypothesize that 1 nanoparticles attach to or near nuclear pores in Caco-2 cells, dissociate,
and are then transported into the nucleus as 1 molecules or clusters.3
(1) R. Iwaura et al, Small, 2010, 6, 1131; R. Iwaura et al Chem. Commun., 2012, 6633.
(2) R. Iwaura et al, J. Photochem. Photobiol. B: Biology, 2014, 130, 199.
(3) R. Iwaura et al, Chem. Commun., 2014, 50, 9295.