Composites of peptide nucleic acids with ttitanium dioxide nanoparticles. I. Construction of nanocomposites containing DNA/PNA duplexes and their delivery into HeLa cells

In order to study the possibility of using titanium dioxide (TiO2) nanoparticles to deliver peptide nucleic acids (PNA) in eukaryotic cells, a PNA oligomer was synthesized, and a method of PNA immobilization in the form of hybrid DNA/PNA duplexes on the surface of TiO2 nanoparticles covered with polylysine (PL) was developed. The attachment of a DNA/PNA duplex to TiO2 · PL nanoparticles occurs due to electrostatic interactions between the negatively charged DNA chain and the positively charged amino groups of PL. The binding of the PNA to the nanocomposite is achieved through noncovalent Watson-Crick interactions between PNA and complementary DNA. The capacity of the obtained TiO2 · PL · DNA/PNA nano-composites depending on immobilization conditions was 10–30 nmol PNA per 1 mg of TiO2 particles, which corresponds to ∼1–3 PNA molecules per one TiO2 particle with a size of 4–6 nm. It was shown by confocal laser scanning microscopy that fluorescently-labeled PNA molecules in the TiO2 · PL · DNA/FluPNA nano-composites effectively penetrate into HeLa cells without transfection agents, electroporation, or other auxiliary procedures.