Peptide Nucleic Acids (PNAs) are nanostructures similar to nucleic acid molecules (synthetic DNA/RNA analogs) wherein the negatively charged backbone (sugar-phosphate) present in DNA/RNA molecules is replaced by a backbone without polyamide or peptide charge. Later, it was found that PNAs containing both purine and pyrimidine bases form highly stable duplexes with DNA and RNA. Although it is not as stable as 2PNA/DNA triplexes containing a homopyrimidine strand, it is still more stable than DNA/DNA and/or DNA/RNA duplexes. The unique characteristics of PNAs add new aspects to these nanostructures relative to conventional analogs to make them appropriate for molecular biology studies. The most important applications include the use of these nanostructures in the detection and treatment of diseases caused by threatening biological agents using the antisense/antigen technology and as genetic regulator drugs.