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Melanoma cells have a poor ability to mediate oxidative stress, which may be attributed to constitutive abnormalities in their melanosomes. We hypothesize that disorganization of the melanosomes will allow chemical targeting of the melanin within. Chemical studies show that under oxidative conditions, synthetic melanins demonstrate increased metal affinity and a susceptibility to redox cycling with oxygen to form reactive oxygen species. The electron paramagnetic resonance (EPR)-active 5,5'-dimethyl-pyrollidine N-oxide spin adduct was used to show that binding of divalent Zn or Cu to melanin induces a pro-oxidant response under oxygen, generating superoxide and hydroxyl radicals. A similar pro-oxidant behaviour is seen in melanoma cell lines under external peroxide stress. Melanoma cultures grown under 95% O2/5% CO2 atmospheres show markedly reduced viability as compared with normal melanocytes. Cu- and Zn-dithiocarbamate complexes, which induce passive uptake of the metal ions into cells, show significant antimelanoma activity. The antimelanoma effect of metal- and oxygen-induced stress appears additive rather than synergistic; both treatments are shown to be significantly less toxic to melanocytes.

Here, we present the investigation of the magnetic properties of Li3V2(PO4)3/Li3PO4 composites, which can be potentially used as a cathode material in lithium-ion batteries. Li3V2(PO4)3/Li3PO4 was synthesized by the thermal hydrolysis method and has a granular mesoporous structure. Magnetic properties of the composite were investigated using magnetometry and electron spin resonance methods. Based on magnetization measurements, the simultaneous existence of the paramagnetic phase with antiferromagnetic interactions between spins of V3+ ions and magnetically correlated regions was suggested. Most probably, magnetically correlated regions were formed due to anti-site defects and the presence of V4+ ions that was directly confirmed by electron spin resonance measurements.

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy (VB−). To explore and utilize the properties of this defect, one needs to design a robust way for its creation in an hBN crystal. We investigate the possibility of creating VB− centers in an hBN single crystal by means of irradiation with a high-energy (E = 2 MeV) electron flux. Optical excitation of the irradiated sample induces fluorescence in the near-infrared range together with the electron spin resonance (ESR) spectrum of the triplet centers with a zero-field splitting value of D = 3.6 GHz, manifesting an optically induced population inversion of the ground state spin sublevels. These observations are the signatures of the VB− centers and demonstrate that electron irradiation can be reliably used to create these centers in hBN. Exploration of the VB− spin resonance line shape allowed us to establish the source of the line broadening, which occurs due to the slight deviation in orientation of the two-dimensional B-N atomic plains being exactly parallel relative to each other. The results of the analysis of the broadening mechanism can be used for the crystalline quality control of the 2D materials, using the VB− spin embedded in the hBN as a probe.

Decomposition of triphenylbismuth dicrotonate in diffused light in bensene in the presence of spin trap of C-phenyl-N-tert-butylnitrone leads to formation of phenyl radicals which are registered as the adduct PhCH(Ph)N(O•)Bu-t. Triphenylbismuth dicrotonate Ph3Bi(O2CCH=CHCH3)2 in benzene solition in the presence of C-phenyl-N-tert-butylnitrone PhCH=N(O)Bu-t decomposes in light. An adduct of phenyl radical and spin trap PhCH(Ph)N(O•)Bu-t was registered by ESR method.

Background: Sea cucumber is a seafood of high nutritional value. During its processing, sea cucumber processing liquor is routinely produced, which is usually discarded as waste. The chemical composition of this processing liquor is similar to sea cucumbers themselves. Hence, valuable ingredients, such as functional polysaccharides, could be obtained from them. Results: Biologically active polysaccharides from sea cucumber processing liquor were extracted through protease hydrolysis and electroosmosis. The analysis revealed that the polysaccharide extract from sea cucumber processing liquor (PESCPL) is predominantly composed of mannose, in addition to some glucose and fucose. The antioxidant activity of PESCPL was analyzed using in vitro. It was demonstrated that PESCPL could effectively scavenge 1,1-diphenyl-2-picrylhydrazyl radicals, hydroxyl radicals, and superoxide anion radicals. The effect of PESCPL was investigated in vivo by using mice model fed with high-fat diets with/without PESCPL supplement. It was shown that PESCPL could increase the catalase and superoxide dismutase activity in the serum and decrease serum malonaldehyde content. Furthermore, mice fed with PESCPL diet showed a considerable decrease in the serum cholesterol and triglyceride levels and an increase in high-density lipoprotein cholesterol levels. Conclusions: Our research highlights that PESCPL is a natural antioxidant and could be utilized as a therapeutic supplement for dyslipidemia.

Understanding of physicochemical interactions of proteins and other biologically significant molecules with shungite nanocarbon (ShC), a graphene family nanomaterial, is required to provide biosafety in various fields of its application including biomedicine. Dynamic characteristics of potential bio-nano interface, characteristics of interaction with the solvent (hydration) carry important information about the types of arising bonds and interactions, the interaction of ligand transfer among them, as well as about the properties of the corresponding bio-nano hybrid forms. The dynamic state of the interface (surface) of carbon nanoclusters in ShC dispersions and protein (bovine serum albumin, BSA) and other biologically significant molecules and ions (sucrose, urea, NaCl, HCl, NaOH) that can affect hydration have been studied using electron spin resonance (ESR) of spin probe based on stearic fatty acid (FA) molecule. A transfer of spin probe (FA) from protein to nanocarbon and vice versa in a mixed dispersion of ShC and BSA has been shown to occur depending on their concentration ratio. Nanoparticle protein corona is probably involved in the transfer. The effect has been observed at ShC concentration an order of magnitude lower than that of protein. This signifies the possibility to influence FA binding and transport by serum albumin using ShC dispersion. This effect can be regulated by additional solutes, as has been observed in the case of sucrose. Nonlinearities of Arrhenius dependences of ESR spin probe spectrum parameters in mixed ShC dispersions may indicate the phase transition as in polymer solutions.

Antibacterial activity of a food conveyor belt is an essential property in some cases. However, every antibacterial chemical is not suitable to contact with food materials. Many metal oxides are suitable option for this purpose. The aim of this study was to investigate antibacterial properties of zinc oxide doped PVC polymer coated with electron spin resonance technique. Therefore, optimum zinc oxide containing PVC paste was prepared and applied to textile surface. Coating construction was designed as double layered, first layer did not contain antibacterial agent, thin second layer contained zinc oxide at 10-35% concentration. Oxygen radicals released from zinc oxide containing polymeric coated surface were spin trapped with DMPO (dimethylpyrroline-N-oxide) spin trap and measured with Electron Spin Resonance (ESR). Besides conveyor belt samples, oxygen radical release from zinc oxide surface was measured with ESR under UV light and dark conditions. Oxygen radical release was determined even at dark conditions. Antibacterial properties were tested with ISO 22196 standard using Listeria innocua species. Measured antibacterial properties were related with ESR results. Higher concentration of zinc oxide resulted in higher antibacterial efficiency. DCFH-DA flourometric assay was carried out to determine oxidative stress insidebacteria. It is tought that, this technique will lead to decrease on the labour and time needed for conventional antibacterial tests.

Abstract A low-temperature electron spin resonance study has been carried out on large-area high-purity polycrystalline two-dimensional few monolayer (ML) 2H MoS2 films synthesized by sulfurization of Mo layers, with intent to atomically assess mobility-degrading detrimental point defects. This reveals the presence of a distinct previously unreported anisotropic defect of axial symmetry about the c-axis characterized by g // = 2.00145 and g ⊥ = 2.0027, with corresponding density (spin S = ½) ~3 × 1012 cm−2 for a 4 ML thick film. Inverse correlation of the defect density with grain size points to a domain boundary associated defect, inherently incorporated during sample growth. Based on the analysis of ESR signal features in combination with literature data, the signal is tentatively ascribed to the a (di)sulfur antisite defect (S or S2 substituting for a Mo atom). Beset by these defects, the grain boundaries thus emerge as an intolerable threat for the carrier mobility and layer functionality.

Electron paramagnetic resonance (EPR) and optical absorption studies of xMgO- (25-x) Li2O-50B2O3-25As2O3 glasses were made by introducing Cu2+ as a spin probe. The EPR spectra of all the glass samples recorded at X-band frequencies have similar spectral features. The Cu2+ ions are in well-defined axial sites, but subjected to small distortion leading to the broadening of the spectra. The spin-Hamiltonian parameter values indicate that the ground state of Cu2+ is dx2- y2 and the site symmetry around Cu2+ ions is tetragonal distorted octahedral. The optical absorption spectra exhibited a broadband corresponding to the d-d transition bands of Cu2+ ion. By correlating EPR and optical data, the bond parameters were evaluated and the values show purely ionic nature for the in-plane σ bonding and in-plane π bonding. The out-of-plane π bonding is moderately covalent.