Studies on interaction of ribonucleotides with zinc ferrite nanoparticles using spectroscopic and microscopic techniques

Interaction of ribonucleotides with zinc ferrite nanoparticles (∼15 nm) prepared by the sol–gel method was studied at physiological pH (∼7.0). Ultra-violet (UV–Vis), Fourier transform infrared (FT-IR), Raman spectroscopy and field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were employed to investigate the interaction of ribonucleotides with zinc ferrite surface. Langmuir and Freundlich adsorption models were used to describe the equilibrium isotherms in the concentration range of 1.0 × 10−4 M−4.0 × 10−4 M of ribonucleotides. The maximum adsorption capacity determined for 5′-GMP, 5′-AMP, 5′-UMP, 5′-CMP was 22.37 mg/g, 17.42 mg/g, 16.03 mg/g and 14.03 mg/g, respectively. Langmuir model was found to show the best fit for experimental data. Adsorption kinetics were studied by pseudo-first order and pseudo-second order kinetic models, and the adsorption process was best described by the pseudo-second order kinetic model. FE-SEM images clearly showed that ribonucleotide adheres onto the zinc ferrite nanoparticles surface. AFM analysis demonstrated that the root mean square roughness (Rms, Sq) and average roughness (Sa) increased from 0.98 nm to 1.80 and 0.67 nm–1.38 nm, respectively following exposure to ribonucleotide. FT-IR spectroscopy revealed that the zinc ferrite nanoparticles interact strongly with the phosphate, carbonyl and amino groups of ribonucleotides. Raman spectra of 5′-AMP-zinc ferrite adduct showed the participation of amino and a phosphate group with zinc ferrite nanoparticles surface.