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

V A Karachevtsev,Ya O Cherkashina,O A Nardid,N T Kartel,A N Lyapunov,A Yu Ivanov,L V Ivanov

doi:10.1155/2019/8083207

Abstract

The change in the microviscosity of erythrocyte membranes and the proteins in blood plasma after graphene oxide addition is studied by the ESR spectroscopy exploiting two spin probes with different lipophilic components in the structures. Experiments with charged spin probe 2 embedded into the erythrocyte membrane showed that the introduction of graphene oxide in small concentrations (∼70 μg/ml) into a suspension of erythrocytes did not lead to significant changes in the microviscosity of their membranes. Correlation times of hydrophobic spin probe 1 adsorbed to hydrophobic pockets of plasma proteins demonstrate a gradual slowdown at the graphene oxide injection into blood plasma that indicates a small deformation of the hydrophobic cavity of protein at the adsorption. However, this protein binding with graphene oxide does not cause the displacement of the spin probe from their hydrophobic cavities, which is evidence about small changes in the protein secondary structure. The obtained results indicate the insignificant cytotoxicity effect of small concentrations of graphene oxide for erythrocytes and blood plasma.

Highlights

In recent years, manufactured graphene nanomaterials have received increasing attention owing to their unique physical and chemical properties, such as high electronic conductivity, good thermal and chemical stability, and excellent mechanical strength
An evaluation of the membranes microviscosity was controlled on the basis of analysis of the intensity and the width of lines assigned to the electron transitions in the triplet state of two stable nitroxyl radicals observed in electron spin (paramagnetic) resonance (ESR) spectra. ese spin probes interacted with external environment; in our case, it was a lipid bilayer of erythrocyte membranes and hydrophobic cavities of proteins of blood plasma or water
We evaluated a environment polarity close to the nitroxyl fragment of spin probe 2 in the erythrocyte membrane by measuring parameter an isotropic splitting constant (Aiso) which is determined as the distance (in gausses (Gs) units) between the low- eld (h+1) and central (h0) components of ESR spectra

Summary

Introduction

In recent years, manufactured graphene nanomaterials have received increasing attention owing to their unique physical and chemical properties, such as high electronic conductivity, good thermal and chemical stability, and excellent mechanical strength. In additional to the above indicated properties, an oxidized form of graphene (graphene oxide (GO)) has a good water dispersibility, a facile surface functionalization, and attractive optical features. All these characteristics make this nanomaterial very attractive in many biomedical applications including biosensing, drug delivery, photothermal and photodynamic therapy, tissue engineering, and imaging of different biological processes in vitro and in vivo [1,2,3,4,5,6,7,8,9]. Important fact is that the SA interaction with GO does not cause the displacement of lipophilic probes from the SA hydrophobic cavities, which indicates preservation of the native structure Sample Probe

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Conclusion