ABSTRACT
A problem of intermolecular interactions of biologically active molecules with nanomaterials, addressed by approaches of modern nanobiophysics, is of both basic and applied importance. Useful functional properties of nanocomposites of redox-active organic dyes with carbon nanoparticles and nanotextured surfaces of inorganic materials are provided namely by their peculiar intermolecular interactions. A novel mass spectrometric approach to study such interactions at the nano-level is overviewed and discussed in the present review. The novelty of the method is in the possibility of evaluating elementary steps of electrons and
proton transfer within the nanocomposites of redox-sensitive dyes, essential for their functioning. Recent achievements of the proposed mass spectrometric approach in monitoring of reduction reactions of imidazophenazine derivatives and cationic methylene blue dye deposited on carbon nanoparticles, mesoporous dioxide films, nanostructured graphite surface, and organic monolayers are highlighted. 7.1 IntroductionElaboration of nanocomposites produced from inorganic nanomaterials and biologically active molecules, dyes in particular, is aimed at the creation of biocompatible materials for pharmacology and biomedicine, as well as biomimetic and functional materials for nanodevices and nanosensors for medical diagnostics [11, 40, 50, 64, 76, 100]. Information on intermolecular interactions in such nanocomposites, required for more efficient design of advanced materials, can be obtained by modern methods of nanobiophysics.A certain range of functions of biomolecules and biologically active compounds involves oxidation/reduction reactions. While the most important example of oxidation is biological breathing, the reduction reactions accompany functioning of proteins and enzymes. Monitoring of the occurrence of reduction reactions during the enzymes interaction with target compounds is employed in some types of biosensors for detection of various biomolecules. Redox-active dyes are used as mediator compounds in such biosensors; their function is to shuttle electrons between the biomolecular component and electrodes of the sensor [25, 66, 68, 103, 106, 109]. To be used in the nanosensors, the redox-sensitive dye must be immobilized on nanomaterials, such as graphene, carbon nanotubes (CNTs), inorganic nanoparticles, or organic layers.In our recent studies, we have developed an approach for evaluating the effect of dye-nanomaterial interactions on redox properties of redox-sensitive dyes, including methylene blue, phenazine, and imidazophenazine derivatives using up-to-date mass spectrometric techniques [7, 13, 19, 27, 28, 31, 55-58, 91, 92, 95-97].
