ZnO Nanoparticles Protect RNA from Degradation Better than DNA.

Gene therapy and RNA delivery require a nanoparticle (NP) to stabilize these nucleic acids when administered in vivo. The presence of degradative hydrolytic enzymes within these environments limits the nucleic acids' pharmacologic activity. This study compared the effects of nanoscale ZnO and MgO in the protection afforded to DNA and RNA from degradation by DNase, serum or tumor homogenate. For double-stranded plasmid DNA degradation by DNase, our results suggest that the presence of MgO NP can protect DNA from DNase digestion at an elevated temperature (65 °C), a biochemical activity not present in ZnO NP-containing samples at any temperature. In this case, intact DNA was remarkably present for MgO NP after ethidium bromide staining and agarose gel electrophoresis where these same stained DNA bands were notably absent for ZnO NP. Anticancer RNA, polyinosinic-polycytidylic acid (poly I:C) is now considered an anti-metastatic RNA targeting agent and as such there is great interest in its delivery by NP. For it to function, the NP must protect it from degradation in serum and the tumor environment. Surprisingly, ZnO NP protected the RNA from degradation in either serum-containing media or melanoma tumor homogenate after gel electrophoretic analysis, whereas the band was much more diminished in the presence of MgO. For both MgO and ZnO NP, buffer-dependent rescue from degradation occurred. These data suggest a fundamental difference in the ability of MgO and ZnO NP to stabilize nucleic acids with implications for DNA and RNA delivery and therapy.

Enzyme and Cancer Cell Selectivity of Nanoparticles: Inhibition of 3D Metastatic Phenotype and Experimental Melanoma by Zinc Oxide.

Biomedical applications for metal and metal oxide nanoparticles are rapidly increasing. Here their functional impact on two well-characterized model enzymes, Luciferase (Luc) or ß-galactosidase (ß-Gal) was quantitatively compared. Nickel oxide nanoparticle (NiO-NP) activated ß-Gal (>400% control) and boron carbide nanoparticle (B4C-NP) inhibited Luc(<10% control), whereas zinc oxide (ZnO-NP) and cobalt oxide (Co3O4-NP) activated ß-Gal to a lesser extent and magnesium oxide (MgO) moderately inhibited both enzymes. Melanoma specific killing was in the order; ZnO > B4C ≥ Cu > MgO > Co3O4 > Fe2O3 > NiO, ZnO-NP inhibiting B16F10 and A375 cells as well as ERK enzyme (>90%) and several other cancer-associated kinases (AKT, CREB, p70S6K). ZnO-NP or nanobelt (NB) serve as photoluminescence (PL) cell labels and inhibit 3-D multi-cellular tumor spheroid (MCTS) growth and were tested in a mouse melanoma model. These results demonstrate nanoparticle and enzyme specific biochemical activity and suggest their utility as new tools to explore the important model metastatic foci 3-D environment and their chemotherapeutic potential.