Репозиторий Университета

© 2021 Elsevier Ltd The functionalization of the bacterial cellulose (BC) surface with a chitosan biopolymer to expand the areas of possible applications of the modified BC is an important scientific task. The creation of such composites in the carbonic acid solutions that were performed in this work has several advantages in terms of being biocompatible and eco-friendly. Quantitative analysis of chitosan content in the composite was conducted by tritium-labeled chitosan radioactivity detection method and this showed three times increased chitosan loading. Different physicochemical methods showed successful incorporation of chitosan into the BC matrix and interaction with it through hydrogen bonds. Microscopy results showed that the chitosan coating with a thickness of around 10 nm was formed in the bulk of BC, covering each microfibril. It was found that the inner specific surface area increased 1.5 times on deposition of chitosan from the solutions in carbonic acid.

© 2020 Elsevier Ltd A laser technology has been developed for fabricating structures from composite layers based on biopolymers: albumin, collagen, and chitosan with single-walled carbon nanotubes (SWCNT). The structures are intended for cardiovascular devices and tissue-engineered implants. This is evidenced by the results of studies. The composite layers were fabricated due to the phase transition of biopolymers and SWCNT aqueous dispersion under the influence of laser pulses. At the same time branched 3D networks of SWCNT were formed in the biopolymer matrix. The threshold energy fluence of laser pulses was determined (0.032–0.083 J/cm2) at which a bimodal distribution of pores was observed. The calculation of contact resistances between nanotubes at percolation units of 3D networks (20–100 kOhm) was carried out. Composite layers fabricated by laser demonstrated conductivity values that were higher (12.4 S/m) than those for layers by thermostat (4.7 S/m). The maximum hardness of the composite layers with SWCNT (0.01 wt%) by laser was 482 ± 10, 425 ± 10, and 407 ± 15 MPa for albumin, collagen and chitosan, respectively. The hardness of the thermostat layers was less than 100 MPa. The viability of endothelial cells in composite layers was improved. The composite layers ensured a normal level of hemolysis during interaction with erythrocytes.

© 2020 Wiley Periodicals LLC A modern immunofluorescence analysis based on spectrally encoded microspheres has found numerous and constantly growing applications in disease diagnosis, environmental supervision, and fundamental science. Here we present an overview of microsphere-based methods of multiplex immunofluorescence analysis and consider such important parameters of beads, that are crucial in most microsphere-based immunoassays, as size distribution, fluorescence stability, magnetic properties, and particle material. The preparation methods of the microspheres with tunable diameter, the introduction of various types of fluorochromes, and magnetic particles into the microspheres are discussed in details. This review also addresses the advantages and disadvantages of different approaches to implement technically bead-based immunofluorescence analysis.

© 2020 Cigarette butts (CBs) represent the most common, though poorly biodegradable, type of waste on Earth. Thrown on the soil surface, they can remain unchanged for years, poisoning surrounding ecosystems with toxins accumulated during the smoking process. However, there is practically no data on the effect of smoked CBs on soil biota or soil animals in particular, nor on the potential of edaphic fauna to facilitate their decomposition. One of the most promising agents among soil animals are earthworms, which are known to be beneficial in the processes of recalcitrant organic matter degradation and stimulation of microbial activity in detrital food webs. In a microcosm experiment with the sod podzolic soil, we aimed at testing the effect of the commonly cultured epigeic earthworm Eisenia fetida (Savigny 1826) on the biodegradation rate of CBs and the possible adverse effects of this waste on the species. The experiment had a full-factorial design with three categorical predictors: CB number (0, 1 and 3 per microcosm); smoking condition (smoked and unsmoked CBs) and two levels of earthworm amendment (0 and 4 per microcosm). During 70 days of the experiment, we did not observe any smoked CB-induced mortality of earthworms. The addition of E. fetida significantly increased the CB mass loss across all treatment combinations. Specifically, earthworms improved the decomposition rate from 30 to 36% (p < 0.05), on average. However, this improvement was mainly associated with CB paper wrapping consumption. The inhibition of CO2 emission in microcosms with CBs and earthworms suggested the direct consumption of this waste by E. fetida, rather than modulation of the degradation potential of a microbial community. E. fetida appears to thus be a moderately promising agent for CB biodegradation with the simultaneous reduction in carbon loss from soil through the microbial channel in the studied soil type. These results open perspectives for the further evaluation of the role of soil macroinvertebrates in recalcitrant organic waste management in general and CBs in particular. We demonstrated that earthworms can efficiently decompose smoked and unsmoked cigarette butts regardless of their toxic potential and simultaneously reduce associated microbial activity.

© 2019 Elsevier B.V. Application of restructured collagen-based biomaterials is generally restricted by their poor mechanical properties, which ideally must be close to those of a tissue being repaired. Here, we present an approach to the formation of a robust biomaterial using laser-induced curing of a photosensitive star-shaped polylactide. The created collagen-based structures demonstrated an increase in the Young's modulus by more than an order of magnitude with introduction of reinforcing patterns (from 0.15 ± 0.02 MPa for the untreated collagen to 51.2 ± 5.6 MPa for the reinforced collagen). It was shown that the geometrical configuration of the created reinforcing pattern affected the scaffold's mechanical properties only in the case of a relatively high laser radiation power density, when the effect of accumulated thermomechanical stresses in the photocured regions was significant. Photo-crosslinking of polylactide did not compromise the scaffold's cytotoxicity and provided fluorescent regions in the collagen matrix, that create a potential for noninvasive monitoring of such materials' biodegradation kinetics in vivo.

© 2019 by the authors. Superior polymers represent a promising alternative to mechanical and biological materials commonly used for manufacturing artificial heart valves. The study is aimed at assessing poly(styrene-block-isobutylene-block-styrene) (SIBS) properties and comparing them with polytetrafluoroethylene (Gore-texTM, a reference sample). Surface topography of both materials was evaluated with scanning electron microscopy and atomic force microscopy. The mechanical properties were measured under uniaxial tension. The water contact angle was estimated to evaluate hydrophilicity/hydrophobicity of the study samples. Materials' hemocompatibility was evaluated using cell lines (Ea.hy 926), donor blood, and in vivo. SIBS possess a regular surface relief. It is hydrophobic and has lower strength as compared to Gore-texTM (3.51 MPa vs. 13.2/23.8 MPa). SIBS and Gore-texTM have similar hemocompatibility (hemolysis, adhesion, and platelet aggregation). The subcutaneous rat implantation reports that SIBS has a lower tendency towards calcification (0.39 mg/g) compared with Gore-texTM (1.29 mg/g). SIBS is a highly hemocompatible material with a promising potential for manufacturing heart valve leaflets, but its mechanical properties require further improvements. The possible options include the reinforcement with nanofillers and introductions of new chains in its structure.

© 2019 WILEY-VCH Verlag GmbH  &  Co. KGaA, Weinheim Hydrophobic segments made of oligo(l,l- or d,l-lactides) or poly(l,l-lactide) are grafted onto chitosan backbone in order to use their amphiphilic behavior to prepare degradable microcarriers intended to be used for tissue engineering. Hydrophilic–lipophilic balance of these copolymers is adjusted playing on the respective length of their hydrophilic and hydrophobic moieties. Thanks to their self-emulsifying properties, these graft copolymers are processed into microspheres in the absence of hydrophilic emulsifier commonly added in the aqueous phase of the oil/water emulsion. The copolymers containing amorphous oligolactide segments of medium length are demonstrated to be the most effective ones for microparticle fabrication. The microparticles are characterized using SEM, EDX, and FTIR. The reactivity of amine group is demonstrated using fluorescein isothiocyanate staining. The resulting microspheres disclose a porous core and a shell enriched by the hydrophilic polysaccharide moieties. Stabilization of the oil/water interface during the microsphere fabrication, total yield, size distribution, and microparticle surface morphology are mainly affected by the macromolecular features of the copolymers.

© 2019 Elsevier Ltd The anionic ring-opening polymerization of carbazole-containing monomers, (9-carbazolylmethyl)thiirane (M1)and (3,6-di-tert-butyl-9-carbazolylmethyl)thiirane (M2), with hexanethiol or pentaerythritol tetrakis(3-mercaptopropionate)(PETMP)as initiators and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)as catalyst at 20 °C in tetrahydrofuran or N,N-dimethylformamide as solvents has been studied. The polymerization of these monomers proceeds in a living fashion affording linear and star-shaped polymers with controlled molecular weight (Mn = 4000–15,000 g mol−1)and relatively low polydispersity (Đ < 1.3). It was demonstrated that end-capping of polymers by trifluoroacetic anhydride allowed to protect thiol end groups from oxidative coupling, which typically leads to the broadening of molecular weight distribution of the synthesized polymers. The thermal, photophysical and electrochemical properties of the synthesized linear and star-shaped polymers were estimated.

© 2018 Elsevier Ltd Human stem cells, including pluripotent, embryonic and mesenchymal, stem cells play pivotal roles in cell-based therapies. Over the past decades, various methods for expansion and differentiation of stem cells have been developed to satisfy the burgeoning clinical demands. One of the most widely endorsed technologies for producing large cell quantities is using microcarriers (MCs) in bioreactor culture systems. In this review, we focus on microcarriers properties that can manipulate the expansion and fate of stem cells. Here, we provide an overview of commercially available MCs and focus on novel stimulus responsive MCs controlled by temperature, pH and field changes. Different features of MCs including composition, surface coating, morphology, geometry/size, surface functionalization, charge and mechanical properties, and their cellular effects are also highlighted. We then conclude with current challenges and outlook on this promising technology.

© 2018 Elsevier B.V. Aiming to explore elevated temperatures as a tool for miniaturization of biodegradable polymer multilayer capsules, assembled on spherical vaterite micron- and submicron-sized particles, we subject the shells composed of dextran sulfate (DS) and poly-L-arginine (Parg) to a heat treatment. Changes of the capsule size are studied at various temperatures and ionic strengths of the continuous phase. Unlike some synthetic polymer multilayer shells (their response to heat treatment depends on the number of layers and their arrangement), the biodegradable Parg/DS capsules exhibit size reduction and profound compaction regardless of their initial size, number of polymer layers and polymer layer sequence. The capsule response to heat is stable at ionic strengths of the continuous phase not exceeding 0.1 M NaCl.

© 2018 Izdatel'stvo Meditsina. All rights reserved. Indomethacin, a non-steroid anti-inflammatory drug (NSAID), has been used in different spheres of medicine since the 1960s. It is successfully administered as an anti-inflammatory and pain-relieving medication in rheumatoid and other diseases. According to recent research, indomethacin may become a promising drug enhancing endogenous remyelination in patients with multiple sclerosis. Also, indomethacin affects cell proliferation and invasion, thus it is used to manage pancreatic cancer in patients with hyperglycemia. In addition, indomethacin can inhibit protein synthesis in colorectal carcinoma and other types of cancer cells. The article reviews modern indomethacin medications and the different dosage forms on the Russian pharmaceutical market. Indomethacin poor water solubility is one of the reasons for decreasing its biopharmaceutical characteristics. According to the conducted research, a prospective way to improve indomethacin solubility and bioavailability is the Solid Dispersion (SD) method. SDs are bi- or multicomponent systems consisting of the drug and the carrier. They are a highly dispersed solid phase of the drug or molecular-dispersed solid solutions with a partial formation of a variable composition complex and a carrier. The article provides a brief overview on different aspects of obtaining, investigating, and applying indomethacin SDs with various polymers.