Nanochemistry and Nanobiotechnology 

Phosphate – nucleotide – nucleic acid: adsorption onto nanocrystalline ceria surface
Markitan O. V.,1  Vlasova N.N.1
1 O.O.Chuiko Institute of Surface Chemistry of the NAS of Ukraine. Generala Naumova Str., 17, Kyiv-03164, Ukraine. 
E-mail: kammar@ukr.net

The high biological activity of ceria nanoparticles has been proved [1, 2]. But an unambiguous explanation of the mechanism of this activity is still absent. Undoubted is the importance of understanding the mechanism of the interaction between nanoceria and biomolecules such as proteins and nucleic acids.
The adsorption of deoxyribonucleic acid (DNA) and its constituents (inorganic phosphate and nucleotides) from aqueous solution onto nanoceria surface has been studied as a function of pH. On the ceria surface in aqueous electrolyte solutions, an electric double layer is formed as a result of the interaction of functional ≡CeOH groups with protons and electrolyte ions. In an acidic solution till pH 6.3 (point of zero charge) the surface hydroxyl groups are mostly protonated. The pH-adsorption edges of DNA, inorganic phosphate, and nucleotides were compared with the state of surface functional groups of cerium oxide. It was shown that inorganic phosphate form either inner sphere covalent or outer sphere electrostatic surface complexes;  the nucleotides bind to the oxide surface predominantly  by electrostatic interaction; and the adsorption of double-stranded DNA occurs mainly with the participation of the phosphate backbone of the molecule, namely because of electrostatic interaction between protonated surface groups and ionized phosphate anions. Heterocyclic bases of nucleotides do not appear to be involved in the adsorption of DNA. The proximity of DNA to the oxide surface due to electrostatic attraction makes possible other types of interactions, for example, dispersion and hydrogen bonds formation.

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