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Chitin/chitosan-glucan complex (ChCsGC) was isolated from Schizophyllum commune (S. commune) and dissolved for the first time in precooled (−15°C) 8wt.% urea/6wt.% NaOH aqueous ...solution. Novel nonwoven microfiber mats were fabricated by wet-dry-spinning technique and evaluated the mechanical of fabrics mats and surface morphology. Isolated and nonwoven mat were characterized employing FTIR-ATR, Optical microscope, TGA, DSC, H/C NMR, SEM and XRD techniques. According to the physical/chemical characterization measurements we can assumed that, the net and the novel dressing mats have the same chemical structure with slightly changes in the thermal stability for the dressing mats.The biological activity of the nonwoven ChCsGC fabric was tested against different types of bacteria exhibiting excellent antibacterial activity. Cell viability of the plain complex and nonwovens mats were evaluated utilizing mouse fibroblast cell line varying concentrations and treatment time. ChCsGC did not show any cytotoxicity against mouse fibroblast cells and the cell-fabrics interaction was also investigated using fluorescence microscope. The novel ChCsGC nonwovens exhibited excellent surgical wound healing ability when tested using rat models.
•WO3-x nanowires modified with APTES are integrated into microsensing platforms.•Gas test results show the functionality of these sensors at room temperature under photoactivation.•Results show ...enhanced sensing properties for the APTES@WO3-x compared to the non-modified WO3-x sensors.•APTES@WO3-x shows improved selectivity to nitrogen dioxide and ethanol.
The sensing properties of (3-aminopropyl)triethoxysilane modified tungsten oxide nanowires (APTES@WO3-x) based sensors towards several gases and vapors are reported in this work. The developed sensors show high sensitivity to ethanol and nitrogen dioxide under UV-irradiation at room temperature (24 °C). Gas sensing results demonstrate enhanced sensing properties for the APTES@WO3-x compared to non-modified WO3-x sensors, with the APTES@WO3-x sensors showing approximately 17 and 20 times more sensitivity to ethanol and nitrogen dioxide, respectively, compared to the non-modified WO3-x sensors. The APTES@WO3-x sensors also display improved selectivity to nitrogen dioxide (oxidizing gas) and ethanol (among other reducing gases including acetone, toluene, hydrogen, and carbon monoxide). These results are attributed to the presence of the reactive amino group at the APTES@WO3-x sensors, which facilitates the chemical interaction with nitrogen dioxide and ethanol and the electron transfer towards/from WO3-x under UV-light excitation.
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In this work alpha tricalcium phosphate (α-TCP)/iron (Fe) composites were developed as a new family of biodegradable, load-bearing and cytocompatible materials. The composites with ...composition from pure ceramic to pure metallic samples were consolidated by pulsed electric current assisted sintering to minimise processing time and temperature while improving their mechanical performance. The mechanical strength of the composites was increased and controlled with the Fe content, passing from brittle to ductile failure. In particular, the addition of 25 vol% of Fe produced a ceramic matrix composite with elastic modulus much closer to cortical bone than that of titanium or biodegradable magnesium alloys and specific compressive strength above that of stainless steel, chromium-cobalt alloys and pure titanium, currently used in clinic for internal fracture fixation. All the composites studied exhibited higher degradation rate than their individual components, presenting values around 200 μm/year, but also their compressive strength did not show a significant reduction in the period required for bone fracture consolidation. Composites showed preferential degradation of α-TCP areas rather than β-TCP areas, suggesting that α-TCP can produce composites with higher degradation rate. The composites were cytocompatible both in indirect and direct contact with bone cells. Osteoblast-like cells attached and spread on the surface of the composites, presenting proliferation rate similar to cells on tissue culture-grade polystyrene and they showed alkaline phosphatase activity. Therefore, this new family of composites is a potential alternative to produce implants for temporal reduction of bone fractures.
Biodegradable alpha-tricalcium phosphate/iron (α-TCP/Fe) composites are promising candidates for the fabrication of temporal osteosynthesis devices. Similar to biodegradable metals, these composites can avoid implant removal after bone fracture healing, particularly in young patients. In this work, α-TCP/Fe composites are studied for the first time in a wide range of compositions, showing not only higher degradation rate in vitro than pure components, but also good cytocompatibility and mechanical properties controllable with the Fe content. Ceramic matrix composites show high specific strength and low elastic modulus, thus better fulfilling the requirements for bone fractures fixation. A significant advance over previous works on the topic is the use of pulsed electric current assisted sintering together with α-TCP, convenient to improve the mechanical performance and degradation rate, respectively.
Biodegradable amphiphilic polyurethane films (bio-PUs) were synthesized by solvent free polyaddition reaction of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(caprolactone) (PCL) as ...macrodiols with hexamethylene diisocyanate. Samples were subsequently heat cured in order to obtain 3D crosslinked structure. Different PCL/PEG ratios allowed controlling the toughness of the resulting bio-PUs. Significant enhancement of Young's modulus, strength and elongation at break was observed at a PCL/PEG molar ratio above 3. The change in the bio-PU mechanical behavior was ascribed to the formation of crystalline PCL domains in the bio-PU network. The presence of PEG increased both the ability to absorb water and the rate of hydrolytic degradation, while PCL increased the cell viability. Prepared solvent free bio-PUs may advantageously be used in medicine as elastic resorbable material applicable against post-surgical adhesions.
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•Pure chitosan was isolated from shrimp shell and the chemical structure was confirmed.•Chitosan citrate/hyaluronan was immobilized onto nonwoven cotton fabrics and the antibacterial ...activity was measured.•Cytotoxicity of the prepared dressing was evaluated against two types of cells.•The new wound dressing accelerated the healing process of diabetic/nondiabetics rats.
Thin layers of chitosan (positively charged)/sodium hyaluronate (negatively charged)/nonwoven fabrics were constructed by polyelectrolyte multilayer pad-dry-cure technique. Pure chitosan (CS) was isolated from shrimp shell and immobilized onto nonwoven fabrics (NWFs) using citric acid (CTA) as cross linker and solvent agents through a pad-dry-cure method. The prepared thin layer of chitosan citrate/nonwoven fabrics (CSCTA/NWFs) were consequently impregnated with hyaluronan (CSCTA/HA/NWFs) in the second path through a pad-dry-cure method. Chitosan/hyaluronan/nonwoven fabrics wound dressing was characterized by different techniques such as FTIR-ATR, TGA and SEM. The antibacterial activity and the cytotoxicity of the dressing sheets were evaluated against Escherichia coli (E. coli) and Streptococcus aureus (S. aureus), mouse fibroblast (NIH-3T3) and keratinocytes (HaCaT) cell lines, respectively. The cell-fabrics interaction was also investigated using fluorescence microscope, based on live/dead staining assay of 3T3 cells. The healing properties of the new wound dressing were evaluated and compared with the control sample.
Bleeding is one of the most commonly occurring injuries; it can be painful and even life-threatening condition. The hemostats are substances that promote blood clotting and fasten hemostasis. In this ...paper, we evaluated the hemostatic effect of freeze-dried wound dressings based on equine collagen, porcine collagen, fibrous carboxymethyl cellulose (CMC) and their mixtures. The wound dressings were investigated for their morphological structure, chemical structure, absorption properties, in vitro hemostasis, cytotoxicity assay and lastly, for in vivo hemostasis. We have found out that adding fibrous CMC into collagen-based hemostatic wound dressings creates a strong synergistic effect, which significantly improves absorption capacity by almost doubling it, as well as supports clotting time. Based on the in vivo studies on partial nephrectomy in rats, the time needed for achieving hemostasis was significantly lower due to the synergy of collagen and CMC. Our materials were compared to the commonly used hemostatic sealing patch on the market (Tachosil) during the in vivo testing, and sample of a mixture of equine collagen and CMC showed better hemostatic efficacy.
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The piezoelectric sensor (quartz crystal microbalance, QCM) was used to monitor cell adhesion in real time. Two cell lines, rat epithelial cells (WB F344) and lung melanoma cells (B16F10) were used. ...The cells were adhered and grown on the gold surface of the sensor pre-coated with adsorbed layer of extracellular matrix proteins as vitronectin and laminin. The process of cell attachment and spreading on the gold surface was continuously monitored and displayed by changes of the resonant frequency Δ
f and resistance Δ
R values of the piezoelectric resonators. The initial phase of cell attachment and spreading induced a decrease of frequency and increase of resistance relating viscoelastic properties of the cell monolayer on the sensing surface. The steady-state of both shifts was achieved after a few hours. The presence and state of cells on the surface was confirmed by fluorescent microscopy. The obtained results demonstrate that the piezoelectric sensor is suitable for studies of the cell adhesion processes. Thus obtained cell-based biosensor has potential for identification and screening of biologically active drugs and other biomolecules affecting cellular shape and attachment.
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