Synthesis,Characterization of Cerium Oxide Nanoparticles and Evaluation of DNA Binding Interaction

Nanotechnology is a multidisciplinary science in the field of research and development which attracts a lot of attention for fundamental studies and potential applications in biomedical field and drug delivery process. Nanoparticles of transition metal oxides exhibit unique properties with an excellent biocompatibility with biomolecules such as DNA. DNA is the primary target molecule for many anti-cancer drugs which provides different sites for binding of metals. Example of these kind of sites are bases of DNA that are electron rich or the groups of phosphate where drug molecule can bind. Rapid innovations in nanotechnology have aided the encouragement of molecular diagnostic techniques, which have substantial benefits as compared to traditional diagnostic techniques in relation to selectivity, sensitivity, and performing of bioassay of DNA and protein markers. Nanoparticles are also being studied as potential carriers of the DNA to the target in order to avoid the shortcomings of liposomes because of its intrinsic issues such as fast blood leakage, inadequate encapsulation, and low stability. Small interfering RNA (siRNA), plasmid DNA, and anti-sense oligonucleotides can all be delivered by nanoparticles, eliminating the uncertain immune response induced by viral vectors (An and Jin, 2012). Cerium oxide nanoparticle (CeO NPs) is one of the potential nanomaterial for biomedical applications. CeO NPs have shown the antibacterial activity against various microorganisms (Rajeshkumar and Naik,2018). Owing to the availability of Ce(III) sites, CeO NPs have been shown to be capable of breaking the phosphate link of para-nitrophenyl phosphate and also O-phospho L-tyrosine and hence exhibit phosphatase mimetic activity. CeO NPs are capable of eliminating peroxynitrite, hydroxyl radical and nitric oxide and hence have anti-oxidant and neuroprotective activity. Considering the various applications, the binding between DNA and CeO NPs will be a potential research domain (Singh et al., 2020). The present work focuses on investigating the DNA binding ability of Cerium Oxide nanoparticles (CeO NPs) in an attempt to design and develop nanoparticles that could be used for various biomedical applications. Cerium oxide NPs had been synthesized by using solution combustion method and hydrothermal method. The structure of NPs was determined by using Scanning electron microscopic technique and powdered Xray diffraction technique (XRD). The obtained XRD pattern for the different synthesis methods confirmed the poly-crystalline nature of CeO NPs. The crystal planes obtained were in accordance with the JCPDS(No:34-0394) of Cerium oxide crystals. The interaction between cerium oxide nanoparticles and Calf thymus-DNA(CT-DNA) was confirmed by UV-visible spectroscopy. The decrease in absorbance of CeO NPs solution on the gradual addition of CT-DNA shows that there is an interaction taking place between the CeO NPs and CT-DNA. The absorbance vs wavelength plot of interaction showed a hypochromic shift with constant absorption maxima. This type of shift indicates that the synthesized CeO NPs bind to CT-DNA by partial or non-intercalative binding. The interaction between CeO NPs and CT-DNA may possibly be due to electrostatic type of interaction and hydrogen bond formation between the nanoparticles and the phosphate groups possessing negative charge present on the DNA backbone. From binding studies, the binding constant Kb was calculated. The Kb value for CeO NPs synthesized by solution combustion method was 5.826 x 104 M-1 and the Kb value for hydrothermal method of 3 h was 0.24 x 104 M-1, for hydrothermal method of 24 h was 3.176 x 104 M-1. The binding constant for the interaction between the CeO NPs synthesized by combustion method showed the highest binding affinity. The present study shows that the method of nanoparticle synthesis has an effect on the interaction between the nanoparticles and the CT-DNA.