Gene therapy is a technique for correcting defective genes responsible for disease development. Gene therapy can be broadly defined as the transfer of defined genetic material to specific target cells of a patient for the ultimate purpose of preventing or altering a particular disease state. Genes and DNA are now being introduced with the use of vectors and various techniques to get high efficiency.
Sometimes, the uptake of drugs with normal cells causes the undesired side effect. To overcome these obstacles, it is necessary to equip the delivery system with various functional devices such as ligands for specific receptors.
Aptamers are artificial nucleic acid molecules that bind to molecular targets, including proteins, with high affinity and specificity. Aptamers are typically from 20 to 50 nucleotides in length and can be composed of DNA, RNA, or peptide nucleic acid (PNA) with a chemically modified sugar backbone (i.e., 2′-fluoro, 2′-O-methyl, phosphorothioate). The secondary structure of aptamers consists primarily of short helical arms and single-stranded loops which are the effective part to bind the target via vander Waals, hydrogen bonding, and electrostatic interactions.