Characteristics and Applications of Peptide Nucleic Acid in the Treatment of Infectious Diseases and the Effect of Antimicrobial Photodynamic Therapy on Treatment Effectiveness

Antibiotic resistance is a growing global problem, so there is an urgent need for new antimicrobial agents and strategies. Peptide nucleic acid (PNA) oligomers could be designed and utilized as gene-specific oligonucleotides to target any infectious agents. Selectivity and high-affinity binding are the main properties of PNA. However, in therapeutic applications, intracellular delivery of peptide nucleic acids is still a challenge. In photodynamic therapy (PDT), which could be a useful adjunct to mechanical and antibiotics in removing pathogenic agents, low-power lasers are used in appropriate wavelength for killing the microorganisms that have been treated with a photosensitizer drug. Antimicrobial photodynamic therapy (aPDT) in combination with lipid-charged nanoparticles of PNA is a promising alternative therapy proposed to control infectious diseases. This review summarizes progress in the uptake of peptide nucleic acids at intracellular targets. In addition, we focus on recent nanoparticle- based strategies to efficiently deliver conventional and chemically modified peptide nucleic acids. The likely impact of using two treatment methods simultaneously, i.e., PNP and PDT, has already been discussed.