Binding of Polycitydylic Acid to Graphene Oxide: Spectroscopic Study and Computer Modeling

Abstract

Hybridization of nucleic acids with graphene nanomaterials is of great interest due to its potential application in genosensing and nanomedicine. In this work we study the interaction between polyribocytidylic acid (poly­(rC)) and graphene oxide (GO). The study involves comparing the UV absorption spectra of the free polymer and the polymer bonded to graphene oxide and analyzing the vibrational structure of the systems and their components using FTIR spectroscopy. Spectral shifts of the electronic and vibrational bands of the poly­(rC) and changes of their thermostability due to the adsorption on GO are observed. Molecular dynamics simulation of the adsorption process of the r­(C)10 and r­(C)30 oligomers on graphene demonstrates their disordering due to the π–π stacking of cytosines on graphene and shows that the longer oligomer adsorbs slower. The binding energies of a single cytosine stacked with graphene in water and in vacuum were determined. The calculated IR lines of the stacked cytosine with graphene are red-shifted by up to 20 cm–1 compared to free cytosine. A strong decrease of the intensities of the cytosine vibrations in the 1800–1400 cm–1 range resulting from the interaction with graphene is revealed in the spectra. When cytosine is adsorbed to graphene oxide, their complex is additionally stabilized by H-bonding. It leads to an increase of the red shifting of the cytosine lines.

Change in the Microviscosity of Erythrocyte Membranes and Proteins in Blood Plasma after Graphene Oxide Addition: The ESR Spectroscopy Study

“…Note that the ultrasound action used in these experiments for preparation of GO aqueous suspensions does not lead to the quantity increase of oxygen-containing groups. Our previous analysis of the size of the GO akes in water suspension prepared by similar method [17] showed that we obtained mainly single layers or bilayers of GO with a lateral size ranging from 0.5 to 2 μm (the average ake size is about 1 μm).…”

“…For more detailed analysis of content of oxygen-containing groups in the GO structure, which may in uence the ESR spectra, the FTIR spectroscopy was exploited. Up to now, the main characteristic absorption bands, which allow unique identi cation of GO, are known [16,17]. In accordance with this assignment, the GO absorption bands of the IR spectrum in the range of 1750-1600 cm −1 are attributed to stretch vibrations of ](C O) mainly of the carbonyl and carboxylic groups ( Figure 3), and the bands in the range of 1600-1500 cm −1 are assigned to stretch vibrations of ](C S) involving fragments of the sp 2hybridized graphene domains.…”

“…In accordance with this assignment, the GO absorption bands of the IR spectrum in the range of 1750-1600 cm −1 are attributed to stretch vibrations of ](C O) mainly of the carbonyl and carboxylic groups ( Figure 3), and the bands in the range of 1600-1500 cm −1 are assigned to stretch vibrations of ](C S) involving fragments of the sp 2hybridized graphene domains. Near 1250 cm −1 , the bands are attributed to the vibrations of (C-O-C) epoxy groups, and near 1100 cm −1 to stretch vibrations of hydroxyl and carboxylic groups (](C-OH)) [16,17]. In GO lm spectra used in our experiments, the most intensive absorption band is located at 1586 cm −1 (Figure 3), which is assigned to stretch ](C S) vibrations of the graphene domain.…”

Graphene Oxide as an Enhancer of Fluorescence

“…. In recent years several researchers have investigated the adsorption phenomenon of biomolecules on GO surface …”

“…[11] Nowadays, GO has been utilized with great interest in the field of near-infrared photothermal treatment of cancer, Alzheimer diseases etc.. [12][13][14] In recent years several researchers have investigated the adsorption phenomenon of biomolecules on GO surface. [6,[15][16] It is deeply-rooted that fluorescence of the organic fluorophore, [17,18] and biomolecules [19,20] were quenched in the presence of graphene oxide. Electron transfer, fluorescence resonance energy transfer (FRET), non-radiative dipole-dipole interaction are commonly responsible for this quenching phenomena.…”