Formation of High-Order Structures in Solution by CBS-Pyrophosphatase from D. hafniense

To solve the question about the oligomeric state of wild-type CBS-pyrophosphatase (CBS-PPase) from D. hafniense, this enzyme has been studied using two independent structural methods: small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryoTEM). The formation of stable high-order structures (large helical associates) in a concentrated protein solution has been observed for the first time. It is also shown for the first time that the formation of these structures is a reversible process and the protein passes to the tetramer form (in which it usually exists in diluted solutions) at ligand attachment. The obtained results are important for understanding the functional features of CBS-PPase (in particular, gaining insight into the pathogenesis of some diseases)

Halloysite nanotubes: Prospects in electrorheology

Electrorheological fluids based on polydimethylsiloxane filled with halloysite nanotubes were studied. The filler structure was characterized by TEM, SEM, and X-ray diffraction. When an electric field is applied to suspensions, their rheological behavior changes – the contribution of the elastic component becomes significant and samples behave like a solid body. The effect of the electric field and filler concentration on the electrorheological behavior was investigated. The influence of water content on the filler structure, as well as on electrorheological and electrophysical properties of suspensions, was considered. Electrorheological fluids filled by halloysite with small water content exhibit slightly higher rheological characteristics under an electric field than dried ones. This study shows the prospects of using halloysite nanotubes as a dispersed phase for electrorheological fluids

Silver Alginate Hydrogel Micro- and Nanocontainers for Theranostics: Synthesis, Encapsulation, Remote Release, and Detection

We have designed multifunctional silver alginate hydrogel microcontainers referred to as loaded microcapsules with different sizes by assembling them via a template assisted approach using natural, highly porous calcium carbonate cores. Sodium alginate was immobilized into the pores of calcium carbonate particles of different sizes followed by cross-linking via addition of silver ions, which had a dual purpose: on one hand, the were used as a cross-linking agent, albeit in the monovalent form, while on the other hand they have led to formation of silver nanoparticles. Monovalent silver ions, an unusual cross-linking agent, improve the sensitivity to ultrasound, lead to homogeneous distribution of silver nanoparticles. Silver nanoparticles appeared on the shell of the alginate microcapsules in the twin-structure as determined by transmission electron microscopy. Remote release of a payload from alginate containers by ultrasound was found to strongly depend on the particle size. The possibility to use such particles as a platform for label-free molecule detection based on the surface enhanced Raman scattering was demonstrated. Cytotoxicity and cell uptake studies conducted in this work have revealed that microcontainers exhibit nonessential level of toxicity with an efficient uptake of cells. The above-described functionalities constitute building blocks of a theranostic system, where detection and remote release can be achieved with the same carrier

Effect of Composition and Molecular Structure of Poly( l -lactic acid)/Poly(ethylene oxide) Block Copolymers on Micellar Morphology in Aqueous Solution

The effect of the hydrophobic block length in diblock (PLLA$_x$-b-PEO$_{113}$, x = 64, 166, 418) and triblock (PLLA$_y$-b-PEO$_{91}$-b-PLLA$_y$, y = 30, 52, 120) copolymers of l-lactic acid and ethylene oxide on the structure of micelles prepared by dialysis was studied by wide- and small-angle X-ray scattering in dilute aqueous solution, dynamic light scattering, transmission electron microscopy, atomic force microscopy, and force spectroscopy. It was found that the size of the crystalline PLLA core is weakly dependent on the PLLA block length. In addition to individual micelles, a number of their micellar clusters were detected with characteristic distance between adjacent micelle cores decreasing with an increase in PLLA block length. This effect was explained by the change in the conformation of PEO chains forming the micellar corona because of their overcrowding. Force spectroscopy experiments also reveal a more stretched conformation of the PEO chains for the block copolymers with a shorter PLLA block. A model describing the structure of the individual micelles and their clusters was proposed

In vitro assessment of electrospun polyamide-6 scaffolds for esophageal tissue engineering

© 2018 Wiley Periodicals, Inc. Artificial tissue-engineered grafts offer a potential alternative to autologous tissue grafts for patients, which can be traumatic. After decellularizing Papio hamadryas esophagus and studying the morphology and physical properties of the extracellular matrix (ECM), we generated electrospun polyamide-6 based scaffolds to mimic it. The scaffolds supported a greater mechanical load than the native ECM and demonstrated similar 3D microstructure, with randomly aligned fibers, 90% porosity, 29 μm maximal pore size, and average fiber diameter of 2.87 ± 0.95 µm. Biocompatibility studies showed that human adipose- and bone marrow-derived mesenchymal stromal cells (AD-MSC and BMD-MSC) adhered to the scaffold surface and showed some proliferation: scaffold cell coverage was 25% after 72 h of incubation when seeded with 1000 cells/mm 2 ; cells elongated processes along the polyamide-6, although they flattened 1.67–4 times less than on cell culture plastic. Human umbilical vein endothelial cells, however, showed poor adherence and proliferation. We thus provide in vitro evidence that polyamide-6 scaffolds approximating the esophageal biomechanics and 3D topography of nonhuman primates may provide a biocompatible substrate for both AD-MSC and BMD-MSCs, supporting their adhesion and survival to some degree. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 253–268, 2019

In vitro assessment of electrospun polyamide-6 scaffolds for esophageal tissue engineering

© 2018 Wiley Periodicals, Inc. Artificial tissue-engineered grafts offer a potential alternative to autologous tissue grafts for patients, which can be traumatic. After decellularizing Papio hamadryas esophagus and studying the morphology and physical properties of the extracellular matrix (ECM), we generated electrospun polyamide-6 based scaffolds to mimic it. The scaffolds supported a greater mechanical load than the native ECM and demonstrated similar 3D microstructure, with randomly aligned fibers, 90% porosity, 29 μm maximal pore size, and average fiber diameter of 2.87 ± 0.95 µm. Biocompatibility studies showed that human adipose- and bone marrow-derived mesenchymal stromal cells (AD-MSC and BMD-MSC) adhered to the scaffold surface and showed some proliferation: scaffold cell coverage was 25% after 72 h of incubation when seeded with 1000 cells/mm 2 ; cells elongated processes along the polyamide-6, although they flattened 1.67–4 times less than on cell culture plastic. Human umbilical vein endothelial cells, however, showed poor adherence and proliferation. We thus provide in vitro evidence that polyamide-6 scaffolds approximating the esophageal biomechanics and 3D topography of nonhuman primates may provide a biocompatible substrate for both AD-MSC and BMD-MSCs, supporting their adhesion and survival to some degree. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 253–268, 2019

Development of Submicrocapsules Based on Co-Assembled Like-Charged Silica Nanoparticles and Detonation Nanodiamonds and Polyelectrolyte Layers

Capsules with shells based on nanoparticles of different nature co-assembled at the interface of liquid phases of emulsion are promising carriers of lipophilic drugs. To obtain such capsules, theoretically using the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and experimentally using dynamic light-scattering (DLS) and transmission electron microscopy (TEM) methods, the interaction of like-charged silica nanoparticles and detonation nanodiamonds in an aqueous solution was studied and their ratios selected for the formation of submicron-sized colloidosomes. The resulting colloidosomes were modified with additional layers of nanoparticles and polyelectrolytes, applying LbL technology. As a model anti-cancer drug, thymoquinone was loaded into the developed capsules, demonstrating a significant delay of the release as a result of colloidosome surface modification. Fluorescence flow cytometry and confocal laser scanning microscopy showed efficient internalization of the capsules by MCF7 cancer cells. The obtained results demonstrated a high potential for nanomedicine application in the field of the drug-delivery system development