Delivery of bleomycin A5 into cells using TiO2 nanoparticles to enhance the degradation of intracellular DNA

Different types of bleomycins are used extensively in cancer therapy. Antibiotics scarcely penetrate through cell membranes, leading to the necessity of using high concentrations of the drug and, therefore, overall body toxicity. To study the penetration of an antibiotic into cells, the fluorescein residue (Flu) was introduced in bleomycin A5 (Blm) to form BlmFlu. It was shown by confocal fluorescent microscopy that BlmFlu in the presence of titanium dioxide nanoparticles (TiO2, 3–5 nm), in contrast to free BlmFlu, efficiently penetrate the cell cytoplasm. After being delivered into cells in the presence of TiO2, Blm appeared to be 7–10 times more efficient than free Blm in the fragmentation of intracellular nucleic acids. The results suggest that nanoparticles are very promising to promote the delivery of antibiotics into cells, which will allow reducing their therapeutic dose.