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In the present work, the mechanical anisotropic behavior of low-carbon (Fe-0.07C) steel processed by asymmetric cold rolling was investigated. Three different types of dynamic recrystallization (DRX) mechanisms (continuous, discontinuous, and geometric) were observed in the microstructure of the 75 % cold-rolled sheet. The average intensity of γ-fiber was remarkably enhanced to 2.8 × R as rolling deformation increased to 50 % due to the formation of many deformation bands. After 75 % cold rolling, the average intensity of γ-fiber was significantly decreased to 1.4 × R due to the creation of new recrystallized grains. The results exhibited that the hardness of the low-carbon steel sheet was 260.1 HV by 75 % cold rolling, which was 1.75 times larger than the initial low-carbon steel sheet. With increasing deformation degree, the average yield and tensile strengths gradually improved and reached a peak value of 844.8 MPa and 881.7 MPa after 75 % cold rolling, respectively, which were 2.8 and 2.1 times that of the initial low-carbon steel sheet. By increasing the rolling reduction up to 50 %, the mechanical anisotropy gradually enhanced and by further increasing the cold deformation to 75 %, the anisotropy rapidly decreased due to the weakening of the γ-fiber texture. The strength was the highest along the transverse direction (90°) in all low-carbon steel sheets, and decreased at 0° and 45°. The dσ/dε-ε curves of the 50 % cold-rolled low-carbon steel sheet for the 45° and 90° tensile directions exhibited two distinct stages during the loading, however, that for the 0° revealed only one stage. A large number of parallel striations were present on the fracture surface of the 50 % deformed low-carbon steel sheet at 90° due to the presence of parallel deformation bands.
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Burn injuries damage skin function and increased the risk of infection. Using natural-inspired antibiotic-free nanofibrous in wound healing has attracted increasing attention. Here, mPEG-Curcumin (mPEG-CUR) was synthesized through a novel, cheap, and high-efficiency method, and incorporated onto poly(vinyl alcohol) (PVA)/zwitterionic poly(sulfobetaine vinylimidazole)-grafted chitosan (CS-g-PNVIS) nanofiber. Due to the lack of electrospinning capability of CS-g-PNVIS and its brittleness, to obtain nanofibers with uniform and bead-free morphology, PVA was used as an electrospinning aid polymer, so that the prepared nanofibers have suitable mechanical properties with an average diameter between 115 ± 18-157 ± 39 nm. The heat-treated nanofibers have adequate swelling and dimensional stability. Time-killing assay proved the antibacterial activity of the mPEG-CUR-loaded nanofibers towards Gram-positive and Gram-negative bacterium. The MTT investigation illustrated the non-cytotoxicity and biocompatibility of the nanofibers. In vivo studies exhibited significant improvement in the mean wound area closure by applying mPEG-CUR nanofibers. The mPEG-CUR-loaded nanofibers showed the highest antioxidant (86 %) power after 40 min. Moreover, nanofibers possess a desirable WVT rate (3.4 ± 0.24-5.5 ± 0.3 kg/m2.d) and good breathability and had the potential to supply a suitable moist environment in the wounded area. This approach can be the beginning of a new path in designing a new generation of nanofiber mats for wound healing applications.
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Queimaduras , Quitosana , Curcumina , Nanofibras , Lesões dos Tecidos Moles , Humanos , Álcool de Polivinil , Curcumina/farmacologia , Bandagens , Queimaduras/tratamento farmacológico , Polietilenoglicóis , Antibacterianos/farmacologiaRESUMO
Researchers have examined different bio-inspired materials in tissue engineering and regenerative medicine to fabricate scaffolds to address tendon regeneration requirements. We developed fibers based on alginate (Alg) and hydroxyethyl cellulose (HEC) by wet-spinning technique to mimic the fibrous sheath of ECM. Various proportions (25:75, 50:50, 75:25) of 1 % Alg and 4 % HEC were blended to this aim. Two steps of crosslinking with different concentrations of CaCl2 (2.5 and 5 %) and glutaraldehyde (2.5 %) were used to improve physical and mechanical properties. The fibers were characterized by FTIR, SEM, swelling, degradation, and tensile tests. The in vitro proliferation, viability, and migration of tenocytes on the fibers were also evaluated. Moreover, the biocompatibility of implanted fibers was investigated in an animal model. The results showed ionic and covalent molecular interactions between the components. In addition, by properly maintaining surface morphology, fiber alignment, and swelling, lower concentrations of HEC in the blending provided good degradability and mechanical features. The mechanical strength of fibers was in the range of collagenous fibers. Increasing the crosslinking led to significantly different mechanical behaviors in terms of tensile strength and elongation at break. Because of good in vitro and in vivo biocompatibility, tenocyte proliferation, and migration, the biological macromolecular fibers could serve as desirable tendon substitutes. This study provides more practical insight into tendon tissue engineering in translational medicine.
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Alginatos , Engenharia Tecidual , Animais , Engenharia Tecidual/métodos , Celulose , Medicina Regenerativa , Tendões , Alicerces TeciduaisRESUMO
In this study, electrospun Poly(vinyl alcohol)/Chitosan-g-Poly (N-vinyl imidazole) (PVA/CS-g-PNVIM) wound dressing containing Titanium dioxide/Curcumin (CUR) was prepared as a novel wound healing system with multifunctional properties, including wound closure, drug release, and antibacterial activity. The wound dressing nanofibers system's mechanical, structural, and biological properties were investigated using tensile testing, degradation, X-ray diffraction, Scanning electron microscopy, Fourier transformed infrared spectroscopy, drug release, and in vivo studies. The nanofiber dressing showed excellent mechanical and hydrolytic degradation stability. CS-g-PNVIM-based nanofibers showed excellent antibacterial activity against both Escherichia coli and Staphylococcus aureus in just 1 h with 90 % growth inhibition, with no cytotoxicity to normal fibroblast cells. The animal studies showed that the wound healing and tissue regeneration process by CS-g-PNVIM-based nanofibers were faster than the control group and was completed in 14 days. In conclusion, the CS-g-PNVIM-based nanofibers are potentially promising for biocompatible antibacterial wound dressing applications with proper exudate absorption.
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Quitosana , Curcumina , Nanofibras , Animais , Antibacterianos/química , Bandagens , Quitosana/química , Curcumina/farmacologia , Escherichia coli , Imidazóis , Nanofibras/química , TitânioRESUMO
Electrically conducting self-healing scaffolds are known as a new series of intelligent biomaterial for regulating Human Adipose Mesenchymal Stem Cells biological behaviors, especially their differentiation to bone cells. Herein, we developed a novel hydrophilic semi-conductive chitosan derivative (CP) and loaded it into the self-healing waterborne polyurethane structure, as a new osteogenic agent. The fabricated scaffolds exhibited excellent shape memory properties with shape fixity (> 97 %) and shape recovery ratio (> 98 %) with excellent self-healing value (> 93 %) at a temperature close to the body temperature. The results of MTT, cell attachment, alkaline phosphatase activity, and alizarin red staining analysis demonstrated that the CP-contained scaffolds promote proliferation of hADSCs and matrix mineralization. Also, by introducing the CP the gene expression level of COL-1, ALP, RUNX2, and OCN were significantly enhanced, in line with matrix mineralization. These multifunctional engineered constructs are promising biomaterials for repairing various bone defects.
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Osso e Ossos/metabolismo , Quitosana/química , Guanidinas/química , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Materiais Biocompatíveis/química , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Condutividade Elétrica , Humanos , Células-Tronco Mesenquimais/metabolismo , Osteoblastos/metabolismo , Osteocalcina/genética , Osteogênese , Poliuretanos/química , Água/químicaRESUMO
We aimed to construct a biodegradable transparent scaffold for culturing corneal endothelial cells by incorporating chitosan nanoparticles (CSNPs) into chitosan/polycaprolactone (PCL) membranes. Various ratios of CSNP/PCL were prepared in the presence of constant concentration of chitosan and the films were constructed by solvent casting method. Scaffold properties including transparency, surface wettability, FTIR, and biocompatibility were examined. SEM imaging, H&E staining, and cell count were performed to investigate the HCECs adhesion. The phenotypic maintenance of the cells during culture was investigated by flow cytometry. Transparency and surface wettability improved by increasing the CSNP/PCL ratio. The CSNP/PCL 50/25, which has the lowest WCA, showed comparable transparency with human acellular corneal stroma. The scaffold was not cytotoxic and promoted the HCECs proliferation as evaluated by MTT assay. Cell counting, flow cytometry, SEM, and H&E results showed appropriate attachment of HCECs to the scaffold which formed a compact monolayer. The developed scaffold seems to be suitable for use in corneal endothelial regeneration in terms of transparency and biocompatibility.
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Quitosana/química , Endotélio Corneano/citologia , Nanopartículas/química , Poliésteres/química , Humanos , Engenharia Tecidual/métodosRESUMO
The feasibility study of utilizing sunflower oil as renewable biomass source to develop highly effective inhibitors for mild steel corrosion (MS) in the 15% HCl medium was done by weight loss, potentiodynamic polarization (PDP), dynamic electrochemical impedance spectroscopy (DEIS), and electrochemical impedance spectroscopy (EIS), supported with energy-dispersive X-ray (EDX), atomic force microscopy (AFM), and field-emission scanning electron microscope (FESEM) techniques. Moreover, a complementary theoretical investigation was carried out to clarify the inhibition mechanism of inhibitors by density functional theory (DFT), density functional based tight-binding (DFTB), and molecular dynamics (MD) simulation approaches. The obtained results confirm that sunflower-oil-based corrosion inhibitor (SFOCI) has a significant anticorrosion property toward the dissolution of MS in 15% HCl solution in the temperature range 20-80 °C. In addition, the results show that SFOCI could provide an inhibition efficiency of 98 and 93% at 60 and 80 °C, respectively. The inhibition mechanism of SFOCIs was mixed-type and their adsorption on the surface of MS was mainly chemisorption. The FESEM and EDX studies proved the presence of SFOCI molecules on the surface of MS. In addition, the adsorption energy of SFOCI indicated an intense interaction between the inhibitor and surface of Fe. The results of this study could open a new window for the design and development of scalable and effective eco-friendly vegetable-oil-based corrosion inhibitors for highly corrosive solutions at high temperatures.
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Ácido Clorídrico/química , Aço/química , Óleo de Girassol/química , Biomassa , Corrosão , Temperatura Alta , Simulação de Dinâmica MolecularRESUMO
Nowadays, vascularization and mineralization of bone defects is the main bottleneck in the bone regeneration field that is needed to be overcome and developed. Here, we prepared novel in-situ formed injectable hydrogels based on chitosan biguanidine and carboxymethylcellulose loaded with vascular endothelial growth factor (VEGF) and recombinant Bone morphogenetic protein 2 (BMP-2) and studied its influence on osteoblastic differentiation of dental pulp stem cells (DPSCs). The sequential release behavior of the VEGF and BMP-2 from hydrogels adjusted with the pattern of normal human bone growth. MTT assay exhibited that these hydrogels were non-toxic and significantly increased DPSCs proliferation. The Real-time PCR and Western blot analysis on CG11/BMP2-VEGF showed significantly higher gene and protein expression of ALP, COL1α1, and OCN. These results were confirmed by mineralization assay by Alizarin Red staining and Alkaline phosphatase enzyme activity. Based on these evaluations, these hydrogel holds potential as an injectable bone tissue engineering platform.
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Proteína Morfogenética Óssea 2/farmacologia , Portadores de Fármacos/química , Hidrogéis/química , Osteogênese/efeitos dos fármacos , Células-Tronco/efeitos dos fármacos , Fator de Crescimento Transformador beta/farmacologia , Fator A de Crescimento do Endotélio Vascular/farmacologia , Proteína Morfogenética Óssea 2/química , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Quitosana/análogos & derivados , Quitosana/toxicidade , Polpa Dentária/citologia , Portadores de Fármacos/toxicidade , Liberação Controlada de Fármacos , Guanidinas/química , Guanidinas/toxicidade , Humanos , Hidrogéis/toxicidade , Osteoblastos/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacologia , Resistência à Tração , Alicerces Teciduais/química , Fator de Crescimento Transformador beta/química , Fator A de Crescimento do Endotélio Vascular/químicaRESUMO
For the first time, the novel type of guided bone regeneration composite nanofibers were prepared by grafting polycaprolactone (PCL) to chitosan (CS) using the copper (I) - catalyzed azide-alkyne cycloaddition (CuAAC) reaction. For improve the bioactivity of scaffolds the magnesium-doped hydroxyapatite (Mg-HA) was used. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H NMR) were applied to characterize the prepared scaffolds. The SEM observations show defect-free uniform composite nanofibers with about 419-495â¯nm diameter. The in vitro cell viability test (MTT assay) show that fabricated scaffolds don't have any significant cytotoxicity. Also, osteoblast-like MG63 cells cultured on the nanofibers which prepared through CuAAC reaction (CS-g-PCL/Mg-HA) show higher antibacterial activity, mechanical properties, and cell attachment compared to CS/PCL/Mg-HA blend scaffolds. Moreover, the Alkaline phosphatase (ALP) activity and Alizarin red S (ARS) staining showed that the introduction of the triazole ring into the chemical structure of the copolymer enhanced bone mineralization ability of the scaffolds. These results suggested that this novel scaffold provides an interesting option for bone repair and regeneration.
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Quitosana/química , Nanofibras/química , Poliésteres/química , Alicerces Teciduais/química , Animais , Materiais Biocompatíveis/química , Regeneração Óssea , Linhagem Celular , Durapatita/química , Humanos , Engenharia Tecidual/métodosRESUMO
In this work sulfonated chitosan (SCS) was introduced as a promising green kinetic methane hydrate and corrosion inhibitor to overcome the incompatibility problem between inhibitors. Evaluation of hydrate inhibition performance of SCS with high-pressure autoclave and micro-differential scanning calorimeter revealed that hydrate formation was delayed 14.3⯱â¯0.2 times and amount of hydrate formed was decreased to 30 % compared to water. The weight loss experiments showed that SCS provides corrosion inhibition efficiency of 95.6⯱â¯0.1 at 5000â¯ppm concentration. SCS is able to increase polarization resistance and decrease corrosion current density according to electrochemical measurements. Study of surface morphology by SEM-EDX and profilometer showed that SCSs suppress corrosion rate and reduce the surface roughness of carbon steel. Quantum chemical study confirmed that the pendant groups caused by chitosan modification interact with carbon steel surface. The findings of this research can provide new opportunities to develop biodegradable materials as KHIs/CIs for flow assurance in oil and gas pipelines.
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In this study, an electrospinning technique was used for the fabrication of novel biomedicated nanofibers which are applied for preventing wound infections and local chemotherapy. CURs containing nanofibers with a crosslinking agent (Si-O-Si network) have been produced through functionalization of graphene oxide with APTES. In vitro drug release profile results showed the novel nanofibers could limit the drug's initial burst release and provide better sustainability in comparison with the blend nanofibers without modified GO. The novel delivery vehicle can inhibit the growth of MRSA and S. epidermidis up to 94% and 88%. Also in vitro cell toxicity experiments which were performed by XTT method on MCF-7, HEP G2 and L929 cell lines showed that anticancer activity of CUR remained intact even after loading into nanofibers. This result suggested that the fGO-Si-CUR including nanofibers were a promising candidate for postoperative chemotherapy.