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Polyvinyl alcohol (PVA), as an important polymeric material, has various applications in industry and medicine. The present study investigated these nanofibers' mechanical properties, including modulus of elasticity (MOE), the adhesion between them and the atomic force microscope probe. The study used an electrospinning system to synthesize PVA nanofibers with different concentrations as well as aligned and random scaffold assemblies. The effect of different concentrations and nanofiber scaffold assemblies on the MOE and adhesion was investigated for the extension and retraction strokes in JPK SPM. The results showed that increasing the PVA concentration increased the MOE but decreased adhesion. Considering the random format of PVA nanofiber scaffolds, the increasing MOE rate and decreasing adhesion rate due to increasing PVA concentration are, respectively, 0.097 Mpa (PVA Concentration %) - 1 and 1.868 Nn (PVA Concentration %) - 1 for extension stroke and for retraction stroke are 0.255 Mpa (PVA Concentration %) - 1 and 4.75 Nn (PVA Concentration %) - 1 . Moreover, using the aligned nanofiber format reduced the MOE, and the adhesion was greater for the retraction strokes than extension strokes, while the situation was reversed for the MOE. Finally, in nanofibers with random format scaffolds, increasing the PVA concentration increased the diameter of the nanofibers. The increasing rate of average nanofiber diameters by increasing PVA concentration is 89.424 nm (PVA Concentration %) - 1 for random and aligned scaffolds. [ABSTRACT FROM AUTHOR]

Mechanical loading influences on the chondrocyte and may promote articular cartilage repair in vivo. That is thought to play a key role in the differentiation of MSCs and in tissue healing and repair. We aimed to evaluate the effect of mechanical Loading of walking on articular cartilage repair. So the stem cells were isolated from the infrapatellar adipose tissue and were seeded on PCL. Then cell-scaffold constructs were sputter-coated with gold and observed by scanning electron microscopy to determine the adhesion of ASCs on the scaffold. ASCs-PCL constructs were transplanted into defects in sheep knees then ASCs on the scaffold was induced by the mechanical loading in vivo. Repaired tissue was evaluated with Q(RT-PCR), immunofluorescence staining, toluidine blue staining and Masson's trichrome staining, the results revealed the largest areas of type II collagen staining, Sox9 expression, aggrecan and presence of chondrocytes in repaired cartilage in experimental groups. Also, the results of this study suggest that mechanical loading of walking could be used to induce ASCs to repair articular cartilage in vivo. [ABSTRACT FROM AUTHOR]

Full-thickness skin defect is one of the main clinical problems, which cannot be repaired spontaneously. The aim of this study was to evaluate the feasibility of combining nanofibers with ADM as a bilayer scaffold for treatment of full-thickness skin wounds in a single-step procedure. The nanofibrous polycaprolactone/fibrinogen scaffolds were fabricated by electrospinning. Subsequently, mesenchymal stem cells were isolated from rat adipose tissues and characterized by flow cytometry. Cell adhesion, proliferation, and the epidermal differentiation potential of adipose-derived stem cells (ADSCs) on nanofibrous scaffolds were investigated by scanning electron microscopy (SEM), alamarBlue, and real-time PCR, respectively. In animal studies, full-thickness excisional wounds were created on the back of rats and treated with following groups: ADM, ADM-ADSCs, nanofiber, nanofiber-ADSCs, bilayer, and bilayer-ADSCs. In all groups, wounds were harvested on days 14 and 21 after treatment to evaluate re-epithelialization, blood vessel density, and collagen content. The results indicated that ADSCs seeded on ADM, nanofiber, and bilayer scaffolds can promote re-epithelialization, angiogenesis, and collagen remodeling in comparison with cell-free scaffolds. In conclusion, nanofiber-ADSCs showed the best results for re-epithelialization (according to histological scoring), average blood vessel density (92.7 ± 6.8), and collagen density (87.4 ± 4.9%) when compared to the control and other experimental groups. [ABSTRACT FROM AUTHOR]

Considering the important factor of bioactive nanohydoxyapatite (nHA) to enhance osteoconductivity or bone-bonding capacity, nHA was incorporated into an electrospun polycaprolactone (PCL) membrane using electrospinning techniques. The viscosity of the PCL and nHA/PCL with different concentrations of nHA was measured and the morphology of the electrospun membranes was compared using a field emission scanning electron microscopy. The water contact angle of the nanofiber determined the wettability of the membranes of different concentrations. The surface roughness of the electrospun nanofibers fabricated from pure PCL and nHA/PCL was determined and compared using atomic force microscopy. Attenuated total reflectance Fourier transform infrared spectroscopy was used to study the chemical bonding of the composite electrospun nanofibers. Beadless nanofibers were achieved after the incorporation of nHA with a diameter of 200-700 nm. Results showed that the fiber diameter and the surface roughness of electrospun nanofibers were significantly increased after the incorporation of nHA. In contrast, the water contact angle (132° ± 3.5°) was reduced for PCL membrane after addition of 10% (w/w) nHA (112° ± 3.0°). Ultimate tensile strengths of PCL membrane and 10% (w/w) nHA/PCL membrane were 25.02 ± 2.3 and 18.5 ± 4.4 MPa. A model drug tetracycline hydrochloride was successfully loaded in the membrane and the membrane demonstrated good antibacterial effects against the growth of bacteria by showing inhibition zone for E. coli (2.53 ± 0.06 cm) and B. cereus (2.87 ± 0.06 cm). [ABSTRACT FROM AUTHOR]

To enhance cell attachment and promote liver functions of hepatocytes cultured in bioreactors, a chitosan nanofiber scaffold was designed and prepared via electrospinning. Effects of the scaffold on hepatocyte adhesion, viability and function were then investigated. Data showed that hepatocytes on chitosan nanofiber scaffold exhibited better viability and tighter cell-substrate contact than cells on regular chitosan film. In addition, urea synthesis, albumin secretion and cytochrome P450 activity of hepatocytes on chitosan nanofiber scaffold were all 1.5 to 2 folds higher than the controls. Glycogen synthesis was also increased as compared with the controls. These results suggested the potential application of this chitosan nanofiber scaffold as a suitable substratum for hepatocyte culturing in bioreactors. [ABSTRACT FROM AUTHOR]