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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 310: 123876, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38290278

RESUMO

In this work, we study two series of the copolymers of L-lactide (LLA) and ε-caprolactone (CL) with the CL molar content of 5, 15, and 30 %. The first series was the commercial semicrystalline granules (Corbion, Netherlands), which we analyzed without any additional modification. The second series was amorphous films, prepared from the granules by hot pressing with the subsequent fast quenching in order to avoid the crystallization. We used Raman spectroscopy in conjunction with the quantum chemical modeling to evaluate the structure of the copolymers. As additional methods, we applied X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC). The main result of our study is the elaboration of the Raman methods of quantitative analysis of the relative contents of the comonomers and the crystallinity degree of the poly(L-lactide-co-ε-caprolactone). These methods are based on measurements of the ratios of the peak intensities of the poly(L-lactide) (PLLA) bands at 411 and 874 cm-1, the PLLA band at 2947 cm-1 and the poly(ε-caprolactone) band at 2914 cm-1. Raman study shows that growth of the CL content causes the monotonous decrease in the crystallinity degree of PLLA blocks. Density functional theory analysis of LLA decamer in the conformation of helix 103 allows us to assign the PLLA Raman bands. The Raman data on the composition and crystallinity degree of the copolymers correlate very well with the results of XRD and DSC studies, as well as with the information on the composition of the copolymers provided by manufacturer.

2.
Carbohydr Polym ; 277: 118792, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34893222

RESUMO

Highly anisometric α-chitin nanoparticles isolated by TEMPO-oxidation were investigated as filler for electrorheological fluids. The dimensions of rod-like particles were determined by AFM and cryo-TEM methods. The rheological behavior of α-chitin nanoparticles in polydimethylsiloxane changes from viscous to elastic under electric field. The yield stress reaches about 220 Pa at 7 kV/mm for 1.0 wt% fluid. Despite the nanosize of particles, the suspensions sedimentation ratio was found to be low (~23%). The electrorheological behavior of the fluids was discussed in terms of the Mason numbers. The stability of fluids response under switching electric field was shown. The activation energy of polarization processes in suspensions was calculated as 58 ± 2 and 64 ± 1 kJ/mol for 0.5 and 1.0 wt% filler content from the impedance spectra. The high aspect ratio (~70) and dielectric permittivity result in high electrorheological activity of α-chitin suspensions at extremely low concentrations (≤1.0 wt%).

3.
Sci Rep ; 11(1): 16004, 2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34362988

RESUMO

In this study, we employed several experimental techniques to investigate structure and magnetic properties of poly(p-xylylene)-MnSb composites synthesized by low-temperature vapor deposition polymerization technique and MnSb films deposited at various temperatures. The presence of MnSb nanocrystallites in the studied films was verified by the results of X-ray diffraction, electron microscopy and Raman spectroscopy studies. The obtained data revealed the formation of Sb-rich sublayer with well-oriented Sb grains near the susbtrate, which seems to act as a buffer for the consequent poly(p-xylylene)-MnSb or MnSb layer growth. Increasing the polymer content results in qualitative change of surface morphology of studied films. At high polymer content the hybrid nanocomposite with MnSb nanoparticles embedded into poly(p-xylylene) matrix is formed. All investigated samples demonstrated detectable ferromagnetic response at room temperature, while the parameters of this response revealed a complex correlation with nominal composition, presented crystal phases and surface morphology of studied films. Estimated values of the Curie temperature of the samples are close to that of bulk MnSb.

4.
Carbohydr Polym ; 256: 117530, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33483048

RESUMO

Novel porous filler for electrorheological fluids was fabricated from chitosan via freeze drying technique. An exceptional electrorheological effect was discovered in suspensions of polydimethylsiloxane (silicone oil) filled by highly porous chitosan particles. The electrorheological activity was studied by rotational rheometry and visualized by optical microscopy. High porosity of the filler allows preparing highly efficient electrorheological fluids at rather low (< 1 wt%) concentration of dispersed phase. The mechanism of chain-like structure formation was considered. The electrorheological behavior of suspensions and the filler structural organization at different concentration were comprehended in terms of dielectric properties. The rheological data were approximated by Bingham and Cho-Choi-Jhon equations. The sedimentation stability of chitosan suspensions in polydimethylsiloxane was significantly affected by particles porosity.


Assuntos
Quitosana/química , Dimetilpolisiloxanos/química , Eletroquímica/métodos , Reologia , Íons , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Polímeros , Porosidade , Resistência ao Cisalhamento , Óleos de Silicone/química , Suspensões , Engenharia Tecidual/métodos , Alicerces Teciduais/química
5.
Heliyon ; 6(8): e04686, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32817899

RESUMO

The article presents classification of the thermosetting materials for bone augmentation. The physical, mechanical, biological, and clinical properties of such materials are reviewed. There are two main types of curable osteoplastic materials: bone cements and hydrogels. Compared to hydrogels, bone cements have high strength features, but their biological properties are not ideal and must be improved. Hydrogels are biocompatible and closely mimic the extracellular matrix. They can be used as cytocompatible scaffolds for tissue engineering, as can protein- and nucleic acid-activated structures. Hydrogels may be impregnated with osteoinductors such as proteins and genetic vectors without conformational changes. However, the mechanical properties of hydrogels limit their use for load-bearing bone defects. Thus, improving the strength properties of hydrogels is one of the possible strategies to achieve the basis for an ideal osteoplastic material.

6.
Int J Biol Macromol ; 139: 161-169, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31369786

RESUMO

Chitin whiskers are promising reinforcing filler for composites due to their mechanical properties, renewable nature and low cost. A new method for preparation of ß-chitin fibrils from squid pens in ascorbic acid aqueous solutions (AscA) was developed. Stirring of the solution with 2 g/l AscA for 2 h disperses the swollen chitin to individualized fibrils with an aspect ratio > 250. The optimal conditions of ß-chitin exfoliation in acrylic acid (AcrA) aqueous solution were found (0.75-2 g/l, 3-4 h). TEMPO-oxidized ß-chitin fibrils were chosen as a reference sample for comparison of different methods. 0.1% chitin suspensions exfoliated in AscA and AcrA solutions show similar gel-like behavior with a storage modulus (G') of 98 ±â€¯23 and 34 ±â€¯12 Pa, respectively, whereas G' of 0.1% dispersion of the TEMPO-oxidized ß-chitin fibrils was 0.015 ±â€¯0.005 Pa only. Composites based on poly(acrylic acid) comprising 1-3 wt% of ß-chitin fibrils were fabricated by polymerization filling. Mechanical properties of the composites were investigated in dry state in the temperature range of 25-250 °C and at controlled relative humidity in the range from 53.6% to 100%. It was revealed that the maximum reinforcing effect is achieved at high temperature (>120 °C) and high relative humidity (≥75.3%RH).


Assuntos
Resinas Acrílicas/química , Quitina/química , Fenômenos Mecânicos , Reologia , Água/química , Suspensões
7.
Adv Colloid Interface Sci ; 268: 64-81, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30953976

RESUMO

Nanodiamond (ND) is one of the most attractive allotropic modification of carbon due to their unique physical and chemical properties. In the present review the current state of science and technology in the field of NDs is analyzed. ND can be used in various application and in different form e.g. as a dispersion phase in suspension, as a filler in composites, etc., so the sedimentation stability of ND in different media are under scrutiny. Thus, theoretical aspects of ND suspension coagulation mechanisms and the methods avoiding it were considered. The dependence of rheological behavior on particles modification was discussed as well. Various methods for the preparation and modification of NDs to obtain particles of various sizes on a nanometer scale with different physicochemical properties were reviewed. The area of practical application for NDs was considered on the example of polymer composites. The various manufacturing methods, mechanical properties and medical aspects for thermosetting, thermoplastic and elastomer ND composites were summarized.

8.
Dokl Biochem Biophys ; 484(1): 48-51, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31012012

RESUMO

To select the optimum method for disinfecting scaffolds before recellularization, the effects of octenisept and chlorhexidine at different concentrations on lung biological matrices before and after decellularization were studied by using morphological methods (studies of biomechanical strength of extracellular matrix fibers) and by analyzing chemiluminescence in rats. Chlorhexidine diluted 1 : 10 had the least damage on the matrix properties and to the greatest extent contributed to disinfection of scaffolds for their further storage and experimental studies.


Assuntos
Anti-Infecciosos Locais/química , Clorexidina/química , Desinfecção/métodos , Matriz Extracelular/química , Pulmão/química , Animais , Ratos
9.
Stomatologiia (Mosk) ; 98(6. Vyp. 2): 12-18, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31957416

RESUMO

Using chitosan as the basis for osteoplastic material, we were dealt with its low biocompatibility. The critical assessment of it is poorly presented in the literature and does not have systematic approaches to solving. The aim of the study was to determine the effect of factors affecting chitosan charge and its free amino groups number on the biocompatibility of hydrogels. Biocompatibility of chitosan compositions were studied in male Wistar rats (n=90). The subcutaneous implantation of chitosan discs and hydrogel caused abundant leukocyte infiltration. The addition of ß-glycerophosphate followed by dialysis slightly reduced the inflammatory response. Treatment with a solution of alkali NaOH and NaHCO3 buffer, on the contrary, intensified the inflammatory response. It is confirmed the effect of charged amino groups of chitosan on leukocyte taxis A decrease in the deacetylation degree (DD) of chitosan to 39.0% led to a statistically significant decrease in leukocyte infiltration. Saturation of chitosan hydrogels with PLA granules reduced by 16% the level of leukocyte infiltration, which was supposedly associated with a decrease in the volume of the hydrogel and an increase in the area of its interaction with blood plasma proteins, which reduce the positive charge of chitosan. The most significant reduction in leukocyte infiltration was achieved with a combination of deacetylated to 39.0% chitosan hydrogel with the addition of 16% by weight highly porous PLA granules.


Assuntos
Quitosana , Hidrogéis , Animais , Materiais Biocompatíveis , Odontologia , Masculino , Ratos , Ratos Wistar
10.
Langmuir ; 34(26): 7690-7697, 2018 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-29874084

RESUMO

This study takes a novel approach to the enhancement of receptor properties of thin-film sensors based on hemicyanine dyes with dithia-aza-crown-ionophoric moiety. By means of in situ UV-vis and X-ray reflectivity (XRR) measurements, it was revealed that the introduction of up to 0.25 mmol of Hg2+ under a preliminarily compressed monolayer, formed on pure water, does not lead to cation binding. This is due to the formation of "head-to-tail" aggregates (H-type), in which ionophoric group is blocked by the neighboring molecule. However, the presence of barium cations in the subphase under the forming Langmuir monolayer of the mentioned compound causes codirectional (head-to-head) orientation of chromoionophore fragments. This provides preorganization of a monolayer structure that facilitates the binding of complementary mercury cations, even in a compressed state: asymmetric sandwich complexes containing two dye molecules coordinate a Hg2+ cation between them. This complex structure was confirmed by molecular modeling based on the electron density distribution calculated from XRR measurement data. Such preorganization of supramolecular ensembles induced by cations, which do not participate in the complex formation with macroheterocyclic receptors, may have applications in fields where strict control of molecular orientation at the interface is required, such as nanoelectronics, sensorics, catalysis, etc.

11.
Stomatologiia (Mosk) ; 96(6): 68-74, 2017.
Artigo em Russo | MEDLINE | ID: mdl-29260770

RESUMO

The article deals with the main types of the polymers used in hydrogel preparation. Their biological, physical and chemical properties was compared. Ways of polymers hardening and prospects of medical application were considered. The prospect of use of chitosan hydrogels activated by osteoinductors as a material for bone augmentation were concluded.


Assuntos
Substitutos Ósseos/química , Hidrogéis/química , Quitosana/química , Humanos
12.
Chem Commun (Camb) ; 53(72): 10070-10073, 2017 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-28840213

RESUMO

Comprehensive analysis of the structure and phase behavior for a number of 2,3,4-tris(dodecyloxy)benzenesulfonates with alkali metal and organic focal groups revealed that the shape of the mesogenic group plays a decisive role in phase behavior of the material. Cubic and layered types of packing prevail when the size of the cation is small and, thus, the shape of the mesogenic molecule is close to conic one. With increasing cation size, the shape becomes more tapered, and columnar mesophases appear to be more stable. Interactions of the focal groups however determine the stability of mesophases. Comparatively strong interactions may, morever, provide substantial deviations from a phase diagram plotting the transition temperatures versus the radius of focal group, as in the case of pyridinium 2,3,4-tris(dodecyloxy)benzenesulfonate.

13.
Bull Exp Biol Med ; 162(4): 488-495, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28243915

RESUMO

Biocompatibility of film and fibrous scaffolds from polylactide-based polymers and the relationship between their architecture and the functional characteristics of mesenchymal stem cells were studied. Cell culturing on polylactide-based film and fibrous matrixes did not deteriorate cell morphology and their proliferation and differentiation capacities. The rate of cell proliferation and penetration in microporous 3D matrices with the same porosity parameters and pore size depended on their spatial organization. The above materials can be used as scaffolds for mesenchymal stem cells for creation of tissue engineering implants. The scaffold size and structure should be determined by the defects in the organs in which the regeneration processes have to be stimulated.


Assuntos
Materiais Biocompatíveis/farmacologia , Células da Medula Óssea/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Poliésteres/farmacologia , Alicerces Teciduais , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/fisiologia , Animais , Materiais Biocompatíveis/química , Células da Medula Óssea/citologia , Células da Medula Óssea/fisiologia , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Condrócitos/citologia , Condrócitos/efeitos dos fármacos , Condrócitos/fisiologia , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/fisiologia , Poliésteres/química , Porosidade , Cultura Primária de Células , Medicina Regenerativa , Engenharia Tecidual
14.
Bull Exp Biol Med ; 162(1): 120-126, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27882461

RESUMO

We analyzed viability of mesenchymal stem cells seeded by static and dynamic methods to highly porous fibrous 3D poly-L-lactide scaffolds with similar physical and chemical properties, but different spatial organization modified with collagen. Standard collagen coating promoted protein adsorption on the scaffold surface and improved adhesive properties of 100 µ-thick scaffolds. Modification of 600-µ scaffolds with collagen under pressure increased proliferative activity of mesenchymal stem cells seeded under static and dynamic (delivery of 100,000 cells in 10 ml medium in a perfusion system at a rate of 1 ml/min) conditions by 47 and 648%, respectively (measured after 120-h culturing by MTT test). Dynamic conditions provide more uniform distribution of collagen on scaffold fibers and promote cell penetration into 3D poly-L-lactide scaffolds with thickness >600 µ.


Assuntos
Células da Medula Óssea/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Poliésteres/farmacologia , Alicerces Teciduais , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/fisiologia , Adesão Celular/efeitos dos fármacos , Técnicas de Cultura de Células , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Colágeno/química , Colágeno/farmacologia , Fluoresceínas , Corantes Fluorescentes , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Poliésteres/química , Porosidade , Cultura Primária de Células , Propídio , Reologia , Engenharia Tecidual
15.
Dokl Biochem Biophys ; 470(1): 375-378, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27817028

RESUMO

The effect of decellularization on the biomechanical properties of macaque lungs was studied. The quality of the biological scaffold was additionally assessed by morphological methods, and the contents of extracellular matrix (ECM) fibers were determined both qualitatively and quantitatively. Histological analysis revealed no damage of structural integrity of ECM components, but the scaffold elasticity significantly decreased, which was confirmed by the changes in the hysteresis loop without a concomitant decrease in peak loads, with the mechanical strength of the samples being retained. These changes require taking additional measures to prevent a decrease in the effective lung volume.


Assuntos
Matriz Extracelular/metabolismo , Pulmão/fisiologia , Engenharia Tecidual , Animais , Fenômenos Biomecânicos , Elasticidade , Macaca mulatta , Masculino , Engenharia Tecidual/métodos , Alicerces Teciduais
16.
Bull Exp Biol Med ; 161(4): 538-41, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27591876

RESUMO

Biocompatibility of a new tracheal matrix is studied. The new matrix is based on polymeric ultra-fiber material colonized by mesenchymal multipotent stromal cells. The experiments demonstrate cytoconductivity of the synthetic matrices and no signs of their degradation within 2 months after their implantation to recipient mice. These data suggest further studies of the synthetic tracheal matrices on large laboratory animals.


Assuntos
Células-Tronco Mesenquimais/citologia , Engenharia Tecidual/métodos , Alicerces Teciduais/efeitos adversos , Alicerces Teciduais/química , Traqueia/citologia , Animais , Células Cultivadas , Masculino , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos C57BL
17.
Langmuir ; 32(2): 637-43, 2016 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-26654539

RESUMO

Supramolecular structure of ultrathin films of hemicyanine dye bearing a crown ether group (CrHCR) was tuned by lateral pressure and investigated by means of compression isotherms, UV-vis and fluorescence spectroscopies, and X-ray reflectivity. Two different types of aggregation were revealed, depending on the absence or the presence of metal cations in the water subphase. While CrHCR forms at high surface pressures head-to-tail stacking aggregates on pure water, changing the subphase to a metal-cation-containing one leads to the appearance of well-defined excimers with head-to-head orientation. The structure of monolayers transferred onto solid supports by the Langmuir-Blodgett (LB) technique was examined by use of X-ray reflectivity measurements and molecular modeling. A model of cation-induced excimer formation in hemicyanine Langmuir monolayers is proposed. Finally, fluorescence emission properties of LB films of CrHCR can be managed by appropriate changes in the subphase composition, this last one determining the type of chromophore aggregation.


Assuntos
Carbocianinas/química , Éteres de Coroa/química , Corantes Fluorescentes/química , Ionóforos/química , Tensoativos/química , Cátions , Luz , Modelos Moleculares , Processos Fotoquímicos , Termodinâmica
18.
Bull Exp Biol Med ; 159(4): 557-66, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26395628

RESUMO

We compared the structure and mechanical properties of scaffolds based on pure collagen, pure chitosan, and a mixture of these polymers. The role of the composition and structure of scaffolds in the maintenance of cell functions (proliferation, differentiation, and migration) was demonstrated in two experimental models: homogeneous tissue analogues (scaffold populated by fibroblasts) and complex skin equivalents (fibroblasts and keratinocytes). In contrast to collagen scaffolds, pure chitosan inhibited the growth of fibroblasts that did not form contacts with chitosan fibers, but formed specific cellular conglomerates, spheroids, and lose their ability to synthesize natural extracellular matrix. However, the use of chitosan as an additive stimulated proliferative activity of fibroblasts on collagen, which can be associated with improvement of mechanical properties of the collagen scaffolds. The effectiveness of chitosan as an additional cross-linking agent also manifested in its ability to improve significantly the resistance of collagen scaffolds to fibroblast contraction in comparison with glutaraldehyde treatment. Polymer scaffolds (without cells) accelerated complete healing of skin wounds in vivo irrespective of their composition healing, pure chitosan sponge being most effective. We concluded that the use of chitosan as the scaffold for skin equivalents populated with skin cells is impractical, whereas it can be an effective modifier of polymer scaffolds.


Assuntos
Quitosana/química , Alicerces Teciduais/química , Animais , Proliferação de Células , Forma Celular , Células Cultivadas , Meios de Cultura/química , Módulo de Elasticidade , Fibroblastos/fisiologia , Humanos , Queratinócitos/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Engenharia Tecidual , Cicatrização
19.
Khirurgiia (Mosk) ; (10): 21-4, 2014.
Artigo em Russo | MEDLINE | ID: mdl-25484147

RESUMO

Pulmonary embolism accounts for sudden death of a third of patients. Endovascular catheter interventions including cava-filter implantation have the great promises for the prevention of pulmonary embolism and treatment of phlebothrombosis in inferior vena cava system. The aim of our research is creation of self-soluble cava-filter for prevention of pulmonary embolism and evaluation of opportunity of one-stage filter implantation. We conducted the series of experiments. We used 18 rabbits as experimental animals. The essence of experiment was to prove the possibility for application and to evaluate the extent of absorption of developed cava-filter in lumen of vena cava. It was revealed that copolymer rods implanted among gluteal muscles fibres and near ear vena completely dissolved after 40-50 days. Health of animals didn't change. The cava-filter dissolved partially. There were not toxic effects. The results suggest that there is need to continue research for developing of cava-filter of soluble copolymer.


Assuntos
Poliésteres , Embolia Pulmonar , Filtros de Veia Cava , Trombose Venosa/complicações , Implantes Absorvíveis , Experimentação Animal , Animais , Procedimentos Endovasculares/instrumentação , Procedimentos Endovasculares/métodos , Humanos , Poliésteres/química , Poliésteres/farmacologia , Embolia Pulmonar/etiologia , Embolia Pulmonar/prevenção & controle , Coelhos , Solubilidade , Veia Cava Inferior/cirurgia
20.
Faraday Discuss ; 174: 313-39, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25277550

RESUMO

This contribution describes recent progress in the design, synthesis and properties of solution-processible star-shaped oligomers and their application in organic photovoltaics. Even though alternative chemistry has been used to design such oligomers, the most successful approach is based on a triphenylamine donor branching center, (oligo)thiophene conjugated spacers and dicyanovinyl acceptor groups. These are mainly amorphous low band-gap organic semiconductors, though crystalline or liquid crystalline ordering can sometimes be realized. It was shown that the solubility, thermal behavior and structure of such molecules in the bulk strongly depend on the presence and position of alkyl groups, as well as on their length. The photovoltaic properties of solution-processed molecules of this type are now approaching 5% which exceeds those of vacuum-sublimed devices. The design rules and future perspectives of this class of organic photovoltaic molecules are discussed.

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