[Composites of peptide nucleic acids with titanium dioxide nanoparticles. II+. Dissociation of DNA/PNA duplexes within TiO2 x polylysine x DNA/PNA nanocomposites and in solution. Effect of polylysine].

When creating effective drugs it is important not only to transport them into the cells, but also important to have the possibility of release them from the "transporter" after delivery into the cell. It was shown that peptide nucleic acids (PNA) in nanocomposite TiO2 x PL x DNA/PNA dissociate with typical shape of the thermal denaturation curve, and polylysine (PL) in the nanocomposite has practically no effect on the dissociation of the DNA/PNA duplexes. These data suggest that the PNA in the nanocomposite TiO2 x PL x DNA/PNA have been immobilized reversible and able to dissociate and be released from TiO2-carrier into solution. In contrast that, the dissociation of DNA/DNA and DNA/PNA duplexes in physiological solution at the presence of PL--was not observed. PL in solution abnormally strong influences on the nature of the optical density dependence on temperature and time for D-duplexes and in a less degree--for P-duplexes. It has been suggested, that PL with DNA/DNA duplexes in physiological solution forms triple polycomplexes (-DNA/DNA x PL)m, consisting of several (m) chains of PL connected with DNA/DNA duplexes. And such polycomplexes able to aggregate and precipitate. PL in solution can interact with DNA/PNA duplexes to form monocomplexes PL x (DNA/PNA)n consisting of one chain PL and one or more (n) DNA/PNA duplexes that do not precipitate, however the dissociation of DNA/PNA duplexes from such monocomplexes is difficult.