The Influence of Magnetic Composite Capsule Structure and Size on Their Trapping Efficiency in the Flow

A promising approach to targeted drug delivery is the remote control of magnetically sensitive objects using an external magnetic field source. This method can assist in the accumulation of magnetic carriers in the affected area for local drug delivery, thus providing magnetic nanoparticles for MRI contrast and magnetic hyperthermia, as well as the magnetic separation of objects of interest from the bloodstream and liquid biopsy samples. The possibility of magnetic objects’ capture in the flow is determined by the ratio of the magnetic field strength and the force of viscous resistance. Thus, the capturing ability is limited by the objects’ magnetic properties, size, and flow rate. Despite the importance of a thorough investigation of this process to prove the concept of magnetically controlled drug delivery, it has not been sufficiently investigated. Here, we studied the efficiency of polyelectrolyte capsules’ capture by the external magnetic field source depending on their size, the magnetic nanoparticle payload, and the suspension’s flow rate. Additionally, we estimated the possibility of magnetically trapping cells containing magnetic capsules in flow and evaluated cells’ membrane integrity after that. These results are required to prove the possibility of the magnetically controlled delivery of the encapsulated medicine to the affected area with its subsequent retention, as well as the capability to capture magnetically labeled cells in flow.     

A One-Pot Approach for Bio-Based Arylamines via a Combined Photooxidative Dearomatization-Rearomatization Strategy

The synthesis of arylamines from renewable resources under mild reaction conditions is highly desired for the sustainability of the chemical industry, where the production of hazardous waste is a prime concern. However, to date, there are very few tools in chemists’ toolboxes that are able to produce arylamines in a sustainable manner. Herein, a robust one-pot approach for constructing bio-based arylamines via a combined photooxidative dearomatization-rearomatization strategy is presented. The developed methodology enables the synthesis of structurally complex amines in moderate-to-good isolated yields using biomass-derived phenols, natural α-amino acids, and naphthols under remarkably mild reaction conditions. For the photooxygenation of phenols, a novel chrysazine-based catalyst system was introduced, demonstrating its efficiency for the synthesis of natural products – hallerone, rengyolone, and the pharmaceutically relevant prodrug DHED.     

Recent advances in the preparation of adsorbent layers for thin‐layer chromatography combined with matrix‐assisted laser desorption/ionization mass‐spectrometric detection

This review is focused on planar chromatography hyphenated with mass‐spectrometric detection for analysis of low‐molecular‐mass solutes. Various kinds of hyphenations are discussed with attention paid to the preparation of thin layer plates suited both for the mass‐spectrometric detection of the resolved solutes direct from thin‐layer plates and for indirect mass‐spectrometric detection of the resolved solutes, performed by scraping, extracting, purifying, and concentrating the analyte from the thin‐layer chromatography plate. Plates with monolithic layers are relatively new for thin‐layer chromatography but they can successfully be combined with mass‐spectrometric technique in a pursuit of comprehensive local sample composition information. Preparation of monolithic layers of different porosity and structure based on organic, inorganic, and composite materials is illustrated together with examples of successful separation and detection of low‐molecular‐mass solutes by means of matrix‐assisted and surface‐assisted laser desorption mass spectrometry.     

Prospects for Using Styrene-Isobutylene-Styrene (SIBS) Triblock Copolymer as a Cusp Material for Leaflet Heart Valve Prostheses: Evaluation of Physicochemical and Mechanical Properties

Search for promising polymer materials as a base for cusps of leaflet heart valve prostheses is a topical problem from the viewpoint of limited durability of fixed biological material. For this purpose, styrene-isobutylene-styrene (SIBS) triblock copolymer was prepared by controlled cationic polymerization. The synthesized SIBS is characterized by the number-average molecular mass M_n = 33 000 and narrow monodisperse molecular-mass distribution (M_w/M_n = 1.3). The ultimate strength of the polymer film was lower than that of xenopericard and ePTFE in the longitudinal direction by a factor of 3.30 and 6.36, respectively (p < 0.05); it was lower than that of ePTFE in the transverse direction by a factor of 4.58 (p < 0.05) and did not differ significantly (p = 0.65) from that of xenopericard in the transverse direction. The relative elongation and Young’s modulus of the SIBS film exceeded those of ePTFE and xenopericard in the longitudinal direction by a factor of 3.00 and 5.68 and in the transverse direction by a factor of 6.50 and 3.86, respectively (p < 0.05). The contact angle for different sides of the SIBS film was 101.6° ± 2.9°/104.4° ± 0.9°. According to the data of atomic force microscopy, the height difference on the SIBS surface usually did not exceed 1 µm, with separate pits of 20–40 µm size. The results of studying the physical properties of the surface and the mechanical properties determining the primary biocompatibility factors in comparison with control materials show that SIBS polymers are promising for making leaflet heart valve prostheses.

     

Navigating α-Synuclein Aggregation Inhibition: Methods,Mechanisms, and Molecular Targets

Parkinson's disease is a yet incurable, age-related neurodegenerative disorder characterized by the aggregation of small neuronal protein α-synuclein into amyloid fibrils. Inhibition of this process is a prospective strategy for developing a disease-modifying treatment. We overview here small molecule, peptide, and protein inhibitors of α-synuclein fibrillization reported to date. Special attention was paid to the specificity of inhibitors and critical analysis of their action mechanisms. Namely, the importance of oxidation of polyphenols and cross-linking of α-synuclein into inhibitory dimers was highlighted. We also compared strategies of targeting monomeric, oligomeric, and fibrillar α-synuclein species, thoroughly discussed the strong and weak sides of different approaches to testing the inhibitors.     

Monolithic capillary columns based on pentaerythritol acrylates for molecular‐size‐based separations of synthetic polymers

Monolithic capillary columns based on pentaerythritol triacrylate and pentaerythritol tetraacrylate were synthesized using different compositions of polymerization mixtures and different polymerization conditions. The impact of porogen type and porogen/monomer ratio on the porosity of synthesized monoliths was investigated. Porogen type appears to be the main factor influencing the separating properties of the monolithic sorbent. Using optimal polymerization conditions (porogen type, porogen/monomer ratio, reaction temperature, time etc.) monoliths with a porous structure optimized for polymer separations can be obtained. The monolithic capillary columns containing porous sorbents with optimized porosity are capable of separating 10 to 12 polystyrene standards in one chromatographic run utilizing both size exclusion chromatography and hydrodynamic chromatography separation mechanisms.     

The effect of anomalous transparency of the water-air interface for a volumetric sound source

Anomalous transparency consists in the passage at certain frequencies of the majority of a source’s radiated energy through an interface, which usually gives strong reflection. Earlier, this effect was established for low-frequency point sources located in a fluid bounded by an air medium. In the case of volumetric sources, additional scattering of waves occurs between the interface of the media and the emitter surface; and the character of the manifestation of this effect is unclear. This work, using the solution to the integral equation corresponding to a boundary value problem, examines the emission of wave energy by spherical sources of different radius and its distribution between the energy flow passing through the water-air interface into the upper half-space and the energy flow going to infinity in the lower half-space. It has been established that the size of the source has virtually no effect on the energy distribution in the low-frequency range, i.e., on the anomalous transparency effect. We also analyze how the relative dimensions of spherical sources affect the energy characteristics in the mid- and high-frequency range.     

An efficient method for selective oxidation of (oxime)Pt(II) to (oxime)Pt(IV) species using <Emphasis Type="Italic">N,N</Emphasis>-dichlorotosylamide

The oxidation of (oxime)Pt^II species using the electrophilic chlorine-based oxidant N,N-dichlorotosylamide (4-CH₃C₆H₄SO₂NCl₂) was studied. The reactions of trans-[PtCl₂(oxime)₂] (where oxime = acetoxime, cyclopentanone oxime, or acetaldoxime) with this oxidant led to trans-[PtCl₄(oxime)₂] products. The oxidation of trans-[Pt(o-OC₆H₄CH = NOH)₂] at room temperature gave trans-[PtCl₂(o-OC₆H₄CH = NOH)₂], whereas the same reaction upon heating was accompanied by electrophilic substitution of the benzene rings.     

Nanostructured crystals of fluorite phases Sr1 ? xRxF2 + x (R = Y, La-Lu) and their ordering: Part III. A study of the refractive indices

The refractive indices n of Sr_{1 − x} R _x F_{2 + x} crystals (R = Y, La-Lu; 0 ≤ x ≤ 0.5) have been measured at wavelengths of 0.436, 0.546, and 0.589 μm. It is established that n increases when there is an increase in the RF₃ content x according to a weakly quadratic law for each R. For the isoconcentration series of Sr_0.9 R _0.1F_2.1 crystals, the change in n in the series of rare earth elements has a pronounced nonlinear character, which reflects the nonmonotonous change in the properties of compounds in the R series. It is shown that the method of molecular refraction additivity can be used to calculate n for Sr_{1 − x} R _x F_{2 + x} crystals. By varying the RF₃ content in them, one can obtain optical media with a gradually varied refractive index n in the range 1.44–1.55, thus filling the gap in the n values between high ones for RF₃ crystals and low ones for crystals of alkaline earth fluorides MF₂. Original Russian Text ? T.M. Glushkova, D.N. Karimov, E.A. Krivandina, Z.I. Zhmurova, B.P. Sobolev, 2009, published in Kristallografiya, 2009, Vol. 54, No. 4, pp. 642–647.     

Alkoxy-derived fine powders of simple and complex oxides

Fine powders of ZrO₂, ZrO₂-Y₂O₃, BaTi_1–x Zr _x O₃ have been obtained by hydrolysis of alkoxides. For preparation of ZrO₂-based materials precipitation from the partially hydrolyzed alkoxides solutions (sols) has been used. Barium titanate-based materials were obtained by hydroxide-alkoxide route with quick hydrolysis of titanium butoxide by excess of water on the first stage. The effect of the hydrolysis conditions on the size, shape, and specific surface area of the oxide powders has been discussed. Some considerations on comparison of the two hydrolytic techniques have been suggested.