The development of effective delivery systems for antitumor drugs with increased specificity and controlled release is one of the challenges for biomedical chemistry. This paper presents studies of non-covalent interactions of human serum albumin, which may be a promising carrier for drug delivery, with antitumor antibiotic doxorubicin and folic acid, which have the potential of a guide ligand. Intermolecular interactions of doxorubicin and folic acid with human serum albumin were studied by spectroscopic methods at various pH levels and temperatures. The binding strength of doxorubicin and folic acid responded differently to pH changes. The affinity of the drug to protein increased with the transition from acidic to alkaline conditions, while pH 7.4 was optimal for binding for folic acid. In the case of the triple system, it was found that there was no significant effect of albumin complexation with folic acid on non-covalent interaction with doxorubicin. As expected, binding to these active compounds altered the conformation of the protein. At the same time, this change was minimal in physiological pH for folic acid and in alkaline for doxorubicin. Additionally, the therapeutic properties of doxorubicin, non-covalently bound to human serum albumin, were shown to be preserved in vitro.

In cubic helimagnets MnSi and Cu2OSeO3with their nearly isotropic magnetic properties, the magnetic structure undergoes helical deformation, which is almost completely determined by the helicoid wavenumberk=D/J, where magnetization field stiffnessJis associated with isotropic spin exchange, andDis a pseudoscalar value characterizing the antisymmetric Dzyaloshinskii-Moriya (DM) interaction. Another magnetic feature of these crystals, also caused by the DM interactions, are antiferromagnetic spin cantings, similar to the ferromagnetic cantings responsible for the phenomenon of weak ferromagnetism. Here we show that cantings can strongly influence the helical order through the value of the parameterD. Changing the cantings in a strong magnetic field is predicted to affect the magnon spectrum of the crystals.

We have conducted a series of scattering experiments at the uranium M4 absorption edge on low-symmetry uranium compounds (U2N3 and U3O8) produced as epitaxial films. At weak and forbidden reflections, we find a resonant signal, independent of temperature, with an energy dependence resembling the imaginary part of the scattering factor. Theory, using the FDMNES code, shows that these results can be reliably reproduced assuming that they originate from aspherical 5f electron charge distributions around the U nucleus. Such effects arise from the intrinsic anisotropy of the 5f shell and from the mixing of the 5f electrons of uranium with the outer 2p electrons of the anions. The good agreement between theory and experiment includes azimuthal scattering dependencies, as well as polarization states of the scattered photons. The methodology reported here opens the way for a deeper understanding of the role of the 5f electrons in the bonding in actinide compounds.

The possibilities provided by the use of circularly polarized X rays in transmission and diffraction geometry for studying the properties of noncentrosymmetric crystals (electronic state, optical activity, absolute chirality, and distribution of chiral domains in multiferroics) are considered.

Nanostructured submicron calcium carbonate particles with sizes of 500 ± 90 and 172 ± 75 nm have been synthesized by mass crystallization in aqueous solutions with addition of glycerol, as well as a mixture of polyethylene glycol, polysorbate, and a cellular medium. CaCO 3 :Si:Fe nanoparticles 65 ± 15 nm in size have been obtained by template synthesis in pores of silica particles. The crystal structure and polymorphism of these particles are studied, and the influence of the size and structure of particles on the efficiency of their loading with a chemotherapy agent, as well as its release under model conditions at different рН, is determined.

The use of X-ray synchrotron radiation makes it possible to observe the polarization, spectral, and angular dependences for diffraction reflections. Their theoretical study calls for application of a tensor approach to describe the interaction of X-rays with atoms of matter. Various representations of the tensor atomic scattering amplitude, results of experimental observations of the anisotropy of resonant X-ray scattering, and the relationship of the electric and magnetic multipole moments on atoms with the properties of forbidden resonant reflections are considered.

Many molecules and crystals are chiral, i.e., can exist as right- and left-handed mirror isomers. It is shown that the absolute configuration of monoatomic chiral crystals, including selenium, tellurium, and β-manganese, can be determined using multi-wavelength diffraction of circularly polarized X-ray radiation.

The possibility of controlled variation of the atomic crystal and electronic structures of a paratellurite crystal under the excitation of intense ultrasonic vibrations has been studied. The resonance diffraction of synchrotron radiation has been used for the first time for such a study. The effect of ultrasonic modulation implemented by means of an acoustic standing wave excited in a high-Q ТеО2 resonator on the structure of the forbidden X-ray 100 reflection has been experimentally demonstrated.

Paratellurite TeO 2 crystals under the application of a strong electric field demonstrate significant changes of the shape of allowed reflections, which are associated with the migration of oxygen vacancies to the surface layers [1]. Similar effect was found earlier in strontium titanate SrTiO 3 and got the name of “migration-induced field-stabilized polar phase” [2]. An experiment was carried out at P23 beamline of PETRA III synchrotron, devoted to the study of the changes in the forbidden reflections 002 and 100 in TeO 2 under applied electric field. These reflections are forbidden in conventional X-ray scattering, but can be observed at the energies close to absorption L-edges of Te, due to appearance of dipole-dipole resonant contribution to the atomic factor of Te. The experiment was carried out at the incident radiation energy, close to L 1 edge of Te 4938 eV. For both reflections the azimuthal dependence and energy spectrum were measured with and without application of electric field. For 002 reflection electric field magnitude was 500 and 750 V/mm, for 100 reflection it was 750 and 1050 V/mm. We have observed a change of azimuthal dependence (Fig.1) caused by the violation of a symmetry in electric field in accordance with the predictions of preliminary theoretical calculations. Also we have observed a change of the energy spectrum at the magnitude It is assumed that this change is caused by appearance of oxygen vacancies in the environment of Te. For reflection this change of the energy spectrum was even more obvious. is justified because in this experimental geometry migration of is

Multiple‐wave X‐ray reflections usually aggravate the measurement of Bragg reflections, especially of weak “forbidden” reflections. Accurate analysis of multiple‐wave peaks usually allows to avoid this. However, multiple‐wave reflections can also provide information about crystal structure, since crystal cell parameters determine the positions of multi‐wave peaks. The forbidden reflections 002 and 100 in paratellurite are measured and an approach based on semi‐kinematical X‐ray scattering used to handle the multiple‐wave interferences is shown here.

Absorption spectra of two orthogonal linearly polarized X-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L-23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the "average" anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

Exploitation of X-ray circular polarized beams to study forbidden Bragg reflections and new information that could be obtained in these experiments are discussed. It is shown that the intensities of such reflections can be different for the right- and left-circular polarizations (i.e. exhibiting circular dichroism) even for the dipole-dipole resonant transitions involved in the scattering process. This difference can be observed only in crystals having no center of inversion. Here, this approach is used to study helicity-dependent resonant diffraction in copper metaborate CuB2O4 single crystal, which is non-centrosymmetric but achiral. Nonetheless, a strong circular dichroism has been observed for hh0 forbidden reflections in the vicinity of the Cu K-edge. This effect is shown to originate from dipolar transitions in Cu atoms occupying the 8(d) Wyckoff position only.

The polarizing spectroscopy techniques in visible range optics have been used since the beginning of the 20th century to study the anisotropy of crystals based on birefringence and optical activity phenomena. On the other hand, the phenomenon of X-ray optical activity has been demonstrated only relatively recently. It is a selective probe for the element-specific properties of individual atoms in non-centrosymmetric materials. We report the X-ray Natural Circular Dichroism (XNCD) imaging technique which enables spatially resolved mapping of X-ray optical activity in non-centrosymmetric materials. As an example, we present the results of combining micro-focusing X-ray optics with circularly polarized hard X-rays to make a map of enantiomorphous twinning in a multiferroic SmFe3(BO3)4 crystal. Our results demonstrate the utility and potential of polarization-contrast imaging with XNCD as a sensitive technique for multiferroic crystals where the local enantiomorphous properties are especially important. In perspective, this brings a novel high-performance method for the characterization of structural changes associated with phase transitions and identification of the size and spatial distribution of twin domains.

Polarized neutron diffraction (PND) is a powerful technique to distinguish a weak magnetic contribution from the total scattering intensity. It can provide a detailed insight into the microscopic spin ordering at the unit cell level, but also into the mesoscopic magnetic ordering, like different types of domain populations. Here we report on the application of this technique to the long-standing problem of determining the absolute direction of the Dzyaloshinskii-Moriya vector in relation to the crystal structure. The proposed PND method, based on the measurement of one representative reflection, is easy to perform and straightforward to interpret. The absolute sign of the Dzyaloshinskii-Moriya interaction (DMI) in MnCO3 has been independently determined by PND and found to be in agreement with recent results obtained by resonant magnetic synchrotron scattering. This validates the method. In addition, the absolute DMI vector direction in the prototypical room-temperature weak ferromagnet alpha-Fe2O3 (hematite) has been determined for the first time. To demonstrate the generality of our method, further examples with different symmetries are also presented. Ab initio calculations of the resulting weak noncollinear magnetization using the QUANTUM ESPRESSO package, considering DMI in addition to the symmetric magnetic exchange interaction, were also conducted and found to be in agreement with the experimental results from PND.

We propose a new method to determine the absolute structure of chiral crystals, which is based on the chiral asymmetry of multiple scattering diffraction. It manifests as a difference in the azimuthal dependence of the forbidden Bragg reflection intensity measured with left and right circularly polarized X-ray beams. Contrary to the existing ones, the suggested method does not use X-ray anomalous dispersion. The difference between the Renninger scans with circularly polarized X-rays has been experimentally demonstrated for the 001 reflection intensities in the right- and left-handed quartz single crystals. A Jmulti-based code on model-independent three-wave-diffraction approach has been developed for quantitative description of our experimental results. The proposed method can be applied to various structures including opaque, organic and monoatomic crystals, even with only light elements. To determine the type of isomer, the Renninger plot of a single forbidden reflection is sufficient.

: Examining forbidden reflections provides valuable information on electronic states and the local environment of resonant atoms in crystals. Experimental studies of two forbidden reflections 002 and 100 in TeO 2 single crystals were performed at photon energies close to the L 1 tellurium absorption edge. It was found that the spectral form corresponding to these two reflections looks almost identical, which is completely unexpected for a highly anisotropic material. Theoretical consideration shows that only one component f xy of the tensor describing dipole-dipole resonance scattering contributes to the 002 reflection, while two components f xy and f xz correspond to the 100 reflection. Numerical calculations show that the latter tensor component is comparable to the first one, but the combination of several geometric factors leads to the fact that its contribution to the spectrum is negligible. This explains the experimentally observed results. The finding shows a way for targeted investigation of single tensor components and makes it possible to compare different spectra and use them the study the physical phenomena in functional materials.

Abstract A new type of surface modification of multichannel sensors on a silicon-on-insulator base, which includes the use of a carbonyldiimidazole bifunctional reagent for the formation of an interfacial layer instead of modified silanes and probes for the specific detection of fragments of matrix troponin ribonucleic acid (analyte) as a marker of the cardiac infarction, is proposed. The influence of passivating the sensor surface activated by carbonyldiimidazole with glycine and aminoethanol at the final modification state on the response of sensors and the level of the background signal is investigated. It is shown that the proposed type of surface modification with glycine treatment provides a highly specific response of ~60% in the case of a picomolar analyte concentration in the solution. Different mechanisms are responsible for an increase in the response and sensor specificity during analyte detection after passivation by glycine and aminoethanol.

Until 2009, the only known quasicrystals were synthetic, formed in the laboratory under highly controlled conditions. Conceivably, the only quasicrystals in the Milky Way, perhaps even in the Universe, were the ones fabricated by humans, or so it seemed. Then came the report that a quasicrystal with icosahedral symmetry had been discovered inside a rock recovered from a remote stream in far eastern Russia, and later that the rock proved to be an extraterrestrial, a piece of a rare CV3 carbonaceous chondrite meteorite (known as Khatyrka) that formed 4.5 billion years ago in the pre-solar nebula. At present, the only known examples of natural quasicrystals are from the Khatyrka meteorite. Does that mean that quasicrystals must be extremely rare in the Universe? In this speculative essay, we present several reasons why the answer might be no. In fact, quasicrystals may prove to be among the most ubiquitous minerals found in the Universe.