Advances in peptide nucleic acid for targeting RNA and genomic DNA

Peptide nucleic acid (PNA) is a synthetic mimic of DNA where the deoxyribose-phosphodiester backbone is replaced with N-(2-aminoethyl) glycine units. The lack of deoxyribose-phosphodiester bonds enhances enzymatic stability and improves binding affinity of PNA with complementary DNA and RNA strands. To enhance target binding, conformational stability, and pharmacological activity, several chemical modifications have been introduced into PNA. Modified PNAs have demonstrated promising preclinical potential as antisense and anti-gene agents, supporting their use in diverse biomedical applications. The limited <i>in vivo</i> biodistribution and cellular uptake of PNA have significantly hindered its clinical development. Enhancing PNA biodistribution using nanoformulations and bioconjugate-based delivery strategies has resulted in substantial <i>in vivo</i> pharmacological effects. Further, with advancements in chemistry and delivery techniques, PNA holds promise in treating genetic diseases, metabolic disorders, cancers, and infectious diseases. This review summarizes PNA's pharmacological mechanisms, chemical modifications, delivery strategies, and therapeutic applications while addressing limitations for clinical translation.