Extracellularly synthesized ZnO nanoparticles interact with DNA and augment gamma radiation induced DNA damage through reactive oxygen species

The present study proposes a green synthesis of highly stable and biocompatible ZnO nanoparticles (ZnONPs) using ferulic acid as the reductant. The biosynthesized nanoparticles were characterized by UV-visible spectroscopy, photoluminescence spectroscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, atomic mass spectroscopy, energy dispersive X-ray spectroscopy and elemental mapping. The characterization results elucidate the formation of crystalline wurtzite structured acicular shaped ZnONPs. Furthermore, the intricate mechanism of ZnONPs-DNA interaction was studied. The binding affinity and mechanism of ZnONPs with calf thymus-DNA interactions were scrutinized and the conformational changes were analyzed. The results reveal the interaction of ZnONPs with DNA in intercalation mode and the values of the binding constant (K) and Stern-Volmer quenching constant (Ksv) were found to be 5.8 x 10(5) M-1 and 4.1 x 10(5) M-1, respectively. Furthermore, gamma radiation induced reactive oxygen species (ROS) generation and DNA damage by ZnONPs were analyzed by various spectrophotometric methods, which unveiled the radiosensitizer role of ZnONPs through the significantly increased generation of ROS. Our current experimental evidence explores the ZnONPs' dual role capacity as DNA binders as well as radiosensitizers. Based on the present research findings we conclude that ZnONPs can be excellent anticancer agents, warranting in vivo studies.