Spectral and structural features of bio-composite films of graphene oxide and molybdenum disulphide with molecules of 5-bromouracyl and 5-bromo-2’-deoxyuridine

Abstract

Background: Recently, composite materials based on nanoparticles and biological molecules have been intensively studied due to the unique physicochemical and biophysical properties and prospects of application in various fields of technology, engineering and medicine. Many laboratories conduct experiments with composite materials based on carbon nanoparticles and various 2D nanomaterials in order to create sensitive biosensors based on them, to develop new functional materials for biology and medicine. A wide range of practical applications requires fundamental knowledge about the structure of the created composites, the interaction energy between the components and their spectral characteristics. Objectives: The purpose of the work was to study the structural features of biocomposite films of graphene oxide (GO) and molybdenum disulfide MoS2 with 5-bromouracil (5BrU) and 5-bromo-2'-deoxyuridine (5BrdU) and to obtain information on the interaction between their components based on data from the infrared Fourier spectroscopy and quantum chemical calculations. Materials and methods: For the measurements, a vacuum infrared Fourier spectrometer was used. The composite films were created by the drop casting method based on graphene oxide from GRAPHENEA, an aqueous suspension of MoS2 molybdenum disulfide powder, as well as 5BrU and 5BrdU biomolecules. For the quantum-chemical calculations of model structures the Gaussian 09 and the Firefly 8.0 programs were used. In last one the GAMESS (USA) program code was partially used. Results: The frequencies and intensities of infrared absorption bands of the biocomposite films (5BrU/GO, 5BrU/MoS2, 5BrdU/GO and 5BrdU/MoS2) with different numbers of biomolecules were obtained. The absorption bands of composite films are assigned to the corresponding types of normal vibrations. The interaction energies in model structures are determined. The amorphous (disordered) structure of 5BrU clusters in 5BrU/GO composites at a low concentration of biomolecules has been established. It is shown that the MoS2 composites are more heterogeneous than the GO composites. Conclusions: The absorption band of CO vibrations with a frequency of 1783 cm–1 as well as the bands of the out-of-plane deformation vibrations γNH of 5BrU are sensitive to the structure of 5BrU clusters in composite films. It has been demonstrated that graphene oxide in the composite films affects the conformational equilibrium of 5BrdU. It has been established that structures with stacking between the pyrimidine ring of a nucleoside and the basal plane of graphene oxide are the most energetically favorable.