**5. Nonviral vector gene delivery**

Nonviral vector consists of either natural vectors (plasmid DNA or small nucleic acids, antisense oligonucleotides, small interfering RNAs) or synthetic vectors (liposomes, cationic polymers) [40]. Naked DNA, usually in plasmid form, is the simplest form of non-viral transferring of a gene into a target cell [41–44].

Nonviral vector delivery is categorized as organic (lipid complexes, conjugated polymers, cationic polymers, etc.) and inorganic systems (magnetic nanoparticles, quantum dots, carbon nanotubes, gold nanoparticles (GNPs), etc.) [45].

To achieve the desired therapeutic efficacy, a suitable carrier system is needed. Nanoparticles can be considered as a good carrier for various therapeutic applications due to the following reasons.

