Theranostic materials for MRI and targeted delivery based on functionalized magnetite nanoparticles

In the last decades, the synthesis of magnetic nanoparticles, in particular magnetite nanoparticles (MNPs), has received increased attention due to their wide range of applications in biomedicine and technology. MNPs can be effectively used for diagnostics and treatment of various diseases. Size, shape, charge and surface chemistry of NPs are fundamental characteristics that determine substantially their properties. Moreover, these characteristics have a big role in the processes of pharmacokinetics and pharmacodynamics. Magnetite nanoparticles are nontoxic, biocompatible and degradable material. Considering current demographic trends in the world and the nature of the dynamics of morbidity, we can expect that even if the average level of cancer incidence will occur more than 15 million new cases of malignant neoplasms in the population each year. It is obviously that the increase of cancer incidence will be occur substantially due to prostate cancer in men, tumors of the colon and rectum in men and women. Thus the problem of creating universal drug (theranostic materials) for early diagnosis and treatment of malignancy becomes more and more actual. The opportunity of application of magnetite nanoparticles in MRI and drug delivery is highly dependent on their sizes and magnetic characteristics. In this work we attempted to create materials based on MNPs for prostate cancer therapy and diagnostics. We carried out synthesis of magnetite nanoparticles with different morphology (cubes, rod-like, star-like and flower-like) and with average size from 10 to 50 nm. Obtained nanoparticles were synthesized by thermal decomposition of iron-containing precursors in high-boiling organic solvents, as well as the aging method in aqueous medium. All nanoparticles were characterized by different physicochemical methods such as: transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, ICP - MS. Also magnetic measurements of samples were carried out. For transfer of MNPs from the organic into the aqueous medium and to prevent aggregation MNPs were functionalized and coated with biocompatible copolymers based on polyethyleneglycol and pluronic. Please click Additional Files below to see the full abstract

Magnetic materials for smart therapy and diagnostics

large potential for a variety of applications. Gold-coated magnetic nanoparticles are a class of nanoparticles that have attracted much attention because of their advantageous characteristics, such as their inertness, non-toxicity, super magneticity, ease of detection in the human body, a magnetic core that is protected against oxidation, their facilitated bio-conjugating ability, catalytic surface, and their potential for a variety of biological applications. Gold-coated nanoparticles have great biocompatibility with the human body with the ability to interact with biomolecules such as polypeptides, DNA, and polysaccharides. Herein we report a synthetic procedure for the preparation of water-soluble Fe3O4, Fe3O4@Au core-shell and dumbbell nanoparticles, simple protocol for their synthesis, purification by exclusion chromatography and method for functionalization of gold surface with a number of sulfur-containing ligands (L-cystein, 3-mercaptopropionic acid, 11-mercaptoundecanoic acid, lipoic acid, HS-PEG-COOH, 2-aminoethanethiol, and others). Finally, magnetic nanoparticles were functionalized by immobilization of enzymes, PSMA targeted ligands, fluorescent dyes. These magnetic nanoparticles were characterized by transmission electron microscopy (TEM), FTIR, DLS and UV-Vis spectroscopy. We describe a distinct effect of non-heating superlow-frequency magnetic fields on the kinetics of chemical reactions catalyzed by the enzymes immobilized on core-shell nanoparticles.The observation is unprecedented and suggests the significance of magneto-mechanochemical effects induced by realignment of MNP magnetic moments in an AC magnetic field rather than traditional heating. Such low frequency and amplitude fields are safe and are not expected to cause any damage to biological tissues. The authors knowledge financial support from Ministry of Education and Science of the Russian Federation (14.607.21.0132, RFMEFI60715X0132)

Розробка електропровідних полімерних гібридних композитів на основі полівінілхлориду та поліетилену

Interest to electrically conducting polymer composite materials in recent times has grown considerably, which is associated with the design of new branches of science and technology. The existing analogues are different in the complexity of production and high cost. One of the ways of solving the problem may be designing polymer composite materials with a combined filler. The research was carried out on creating electrically conducting hybrid polymer composites, based on emulsion polyvinyl chloride and polyethylene, using fillers of varying nature and dimensions. We studied the dependence of electrical conductivity of mono­ and binary­filled polymer composites on the type and content of fillers. It was found that the binary filling allows designing electrically conducting polymer composites, which are more promising economically compared to mono­filled ones. We defined physical and mechanical characteristics: tensile strength and relative elongation at break of obtained polymer composites. A method to improve them was proposed by introduction of a compatibilizer – graft­polymer of polyethylene with maleic anhydride.Depending on the value of the electrical conductivity, polymer hybrid composites can be used for: at a value of of elecrical conductivity 10–4–10–7Cm/cm as anti­static materials; at 101–10–4 Cm/cm – as scattering anti­static materials, at 101– 104 Cm/cm as current­conducting materials.Разработаны электропроводящие полимерные гибридные композиты на основе эмульсионного поливинилхлорида (ЭПВХ) и линейного полиэтилена (ПЭ). Исследована зависимость электропроводности моно- и бинарнонаполненных полимерных композитов от вида и содержания наполнителей. Определены физико-механические характеристики полученных полимерных композитов и предложен способ их улучшения. Приведены области применения полученных полимерных гибридных композитов (ПГК) в соответствии со свойственными им значениями электропроводности.Розроблено електропровідні полімерні гібридні композити на основі емульсійного полівінілхлориду (ЕПВХ) та лінійного поліетилену (ПЕ). Досліджено залежність електропровідності моно- та бінарнонаповнених полімерних композитів від виду та вмісту наповнювачів. Визначено фізико-механічні характеристики отриманих полімерних композитів та запропоновано спосіб їх покращення. Наведено сфери застосування отриманих полімерних гібридних композитів (ПГК) відповідно до властивих їм значень електропровідності

HN- та N-метиліміни формальдегіду, ацетальдегіду й ацетону: електронна будова та бар’єри інверсії атома нітрогену

Методом DFT розраховано геометричні та електронні параметри імінів, досліджено передачу електронних ефектів і фактори, які впливають на бар’єри інверсії атома N (ΔEi¹). Установлено, що зменшення негативних зарядів на атомах N та =С під час N- і С-метилування відповідно обумовлене більшою електронегативністю атома С порівняно з атомом Н; зростання значень qN зі збільшенням ступеня С-метилування викликане збільшенням надспряження метильних груп з розпушувальними орбіталями зв’язку С=N. Розглянуто основні дво- та чотириелектронні взаємодії, які впливають на зміни бар’єрів інверсії атома N; домінуючий вплив на величину  ΔEi¹ має електронегативність N-замісників та стеричне напруження, а не внутрішньомолекулярні взаємодії

Stacks of Azobenzene Stars: Self-Assembly Scenario and Stabilising Forces Quantified in Computer Modelling

In this paper, the columnar supramolecular aggregates of photosensitive star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core and azobenzene arms are analyzed theoretically by applying a combination of computer simulation techniques. Without a light stimulus, the azobenzene arms adopt the trans-state and build one-dimensional columns of stacked molecules during the first stage of the noncovalent association. These columnar aggregates represent the structural elements of more complex experimentally observed morphologies-fibers, spheres, gels, and others. Here, we determine the most favorable mutual orientations of the trans-stars in the stack in terms of (i) the p - p distance between the cores lengthwise the aggregate, (ii) the lateral displacements due to slippage and (iii) the rotation promoting the helical twist and chirality of the aggregate. To this end, we calculate the binding energy diagrams using density functional theory. The model predictions are further compared with available experimental data. The intermolecular forces responsible for the stability of the stacks in crystals are quantified using Hirshfeld surface analysis. Finally, to characterize the self-assembly mechanism of the stars in solution, we calculate the hydrogen bond lengths, the normalized dipole moments and the binding energies as functions of the columnar length. For this, molecular dynamics trajectories are analyzed. Finally, we conclude about the cooperative nature of the self-assembly of star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core in aqueous solution

Stacks of Azobenzene Stars: Self-Assembly Scenario and Stabilising Forces Quantified in Computer Modelling

In this paper, the columnar supramolecular aggregates of photosensitive star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core and azobenzene arms are analyzed theoretically by applying a combination of computer simulation techniques. Without a light stimulus, the azobenzene arms adopt the trans-state and build one-dimensional columns of stacked molecules during the first stage of the noncovalent association. These columnar aggregates represent the structural elements of more complex experimentally observed morphologies—fibers, spheres, gels, and others. Here, we determine the most favorable mutual orientations of the trans-stars in the stack in terms of (i) the π – π distance between the cores lengthwise the aggregate, (ii) the lateral displacements due to slippage and (iii) the rotation promoting the helical twist and chirality of the aggregate. To this end, we calculate the binding energy diagrams using density functional theory. The model predictions are further compared with available experimental data. The intermolecular forces responsible for the stability of the stacks in crystals are quantified using Hirshfeld surface analysis. Finally, to characterize the self-assembly mechanism of the stars in solution, we calculate the hydrogen bond lengths, the normalized dipole moments and the binding energies as functions of the columnar length. For this, molecular dynamics trajectories are analyzed. Finally, we conclude about the cooperative nature of the self-assembly of star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core in aqueous solution

New Approach for Extrusion Additive Manufacturing of Soft and Elastic Articles from Liquid-PVC-Based Consumable Materials

The article deals with the experimental development of a novel additive manufacturing (AM) process using a liquid consumable based on polyvinyl chloride plastisol. A conventional additive manufacturing system designed for deposition of melt filaments was converted to deposition of liquid material. Additive manufacturing with liquid plastisol enables the production of parts with low Shore A hardness and high ductility, surpassing the performance of the conventional filament process. The novel AM process enables the production of articles with a Shore A hardness of 5 to 60, and the mechanical properties of the additively manufactured articles are similar to those produced in the mold. This was achieved by varying the parameters of the AM process as well as the composition of the plastisol composition, including those filled with an inorganic filler. The application of different material distribution patterns also has a significant effect on the mechanical properties of the samples. A potential application of the investigated AM method was proposed and practically evaluated

Design of Electrically Conducting Polymer Hybrid Composites Based on Polyvinyl Chloride and Polyethylene

Interest to electrically conducting polymer composite materials in recent times has grown considerably, which is associated with the design of new branches of science and technology. The existing analogues are different in the complexity of production and high cost. One of the ways of solving the problem may be designing polymer composite materials with a combined filler. The research was carried out on creating electrically conducting hybrid polymer composites, based on emulsion polyvinyl chloride and polyethylene, using fillers of varying nature and dimensions. We studied the dependence of electrical conductivity of mono­ and binary­filled polymer composites on the type and content of fillers. It was found that the binary filling allows designing electrically conducting polymer composites, which are more promising economically compared to mono­filled ones. We defined physical and mechanical characteristics: tensile strength and relative elongation at break of obtained polymer composites. A method to improve them was proposed by introduction of a compatibilizer – graft­polymer of polyethylene with maleic anhydride.Depending on the value of the electrical conductivity, polymer hybrid composites can be used for: at a value of of elecrical conductivity 10–4–10–7Cm/cm as anti­static materials; at 101–10–4 Cm/cm – as scattering anti­static materials, at 101– 104 Cm/cm as current­conducting materials

Effect of “ColdArc” WAAM Regime and Arc Torch Weaving on Microstructure and Properties of As-Built and Subtransus Quenched Ti-6Al-4V

Defect-free thin-walled samples were built using wire arc additive manufacturing (WAAM) combined with the “coldArc” deposition technique by feeding a Ti-6Al-4V welding wire and using two deposition strategies, namely with and without the welding torch weaving. The microstructures formed in these samples were examined in relation to mechanical characteristics. The arc torch weaving at 1 Hz allowed us to interfere with the epitaxial growth of the β-Ti columnar grains and, thus, obtain them a lower aspect ratio. Upon cooling, the α/α′+β structure was formed inside the former β-Ti grains, and this structure proved to be more uniform as compared to that of the samples built without the weaving. The subtransus quenching of the samples in water did not have any effect on the structure and properties of samples built with the arc torch weaving, whereas a more uniform grain structure was formed in the sample built without weaving. Quenching resulted also in a reduction in the relative elongation by 30% in both cases