Cellular uptake of phosphorothioate oligonucleotide facilitated by cationic porphyrin: A microfluorescence study

Abstract

Cationic 5,10,15,20-tetrakis (1-methyl-4-pyridyl) porphyrin was tested as a delivery agent for oligonucleotides. By using fluorescence microimaging, it has been shown that complexation of the porphyrin to the phosphorothioate analog of dT(15) labeled by rhodamine enabled its nonendocytic penetration into the cell and regular distribution in the cytoplasm and preferentially into the nucleus. Time-resolved microfluorescence spectroscopy revealed that the oligonucleotide integrity was kept. A small fraction of the porphyrin molecules seems to undergo change of the binding mode after internalization, probably due to duplex formation between the oligonucleotide and its cellular target sequences, or due to dissociation of the porphyrin from the oligonucleotide and subsequent interactions in the cellular environment.

Cellular uptake of modified oligonucleotides enhanced by porphyrins studied by time-resolved microspectrofluorimetry and fluorescence imaging techniques

“…Lifetime shortenings of both fluorophores in ATTO-dT 15 /H 2 TMPyP4 complex probably indicate noncovalent interactions in nuclear environment. However, this fact is rather in contrary to our previous experiments performed with B16 melanoma cell line, incubated with complexes of rhodamine labeled oligonucleotide and non-zinc cationic porphyrin (H 2 TMPyP4), for which two longer distinct lifetimes of porphyrin (14.4 ns and 5.8 ns) were obtained and interpreted as a consequence of its partial dissociation from oligonucleotides in the cell nucleus [11].…”