  Peptide nucleic acids (PNAs) are artificial nucleic acids with a peptide
backbone instead of sugar phosphate backbone of DNA or RNA. Their resistance to
degradation, selectivity and greater binding affinity in comparison to usual
nucleic acids led to consideration of their great potential for different
applications. For example, they can be used in molecular diagnostics and
antisense therapeutics such as antimicrobial agents or gene regulatory tools.
On the other hand, large hydrophilic property of PNA molecules, which inhibit
them to cross cell membranes readily, is an obstacle for their delivery to
considered target cells and a limiting criterion for their applications.
Therefore, PNA delivery technologies have been developing to hurdle this
limitation. For example, addition of lysine residues, charged membrane
penetrating peptide sequences, PNAs conjugated with antibodies or steroids,
cationic liposomes as carriers of PNA conjugates, protective peptides and
technology of photochemical internalization (PCI) as well as by the recent
technology of nanoparticle-based delivery have been employed. In this article
we compared different delivery technologies which can be applicable to PNAs. As
a result nanoparticle-based delivery showed more advantages in comparison to
others and its application is growing fast. Keywords: Target cell delivery,
Peptide nucleic acid, PNA, Delivery.
