Effect of surface chemistry-modified polycaprolactone scaffolds on osteogenic differentiation of stem cells from human exfoliated deciduous teeth.

The aim of this study was to investigate the effect of surface modification of a polycaprolactone scaffold on promoting osteogenic differentiation of stem cells from human exfoliated deciduous teeth. Four different polycaprolactone scaffold were evaluated: untreated; coated with hyaluronic acid; coated with gelatin; and coated with hyaluronic acid and then with gelatin. The resulting scaffolds were characterized using scanning electron microscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Human stem cells were cultured on the modified scaffolds placed in osteogenic differentiation medium. During culture, the osteogenic potential of the stem cells was examined by evaluating alkaline phosphatase activity and staining intensity, expression of osteoblastic-specific genes, and matrix mineralization. Scanning electron microscopy and ATR-FTIR confirmed productive biomacromolecular surface treatment of the polycaprolactone scaffold. All scaffolds permitted differentiation of stem cells into osteoblastic cells, but the gelatin-coated polycaprolactone scaffold facilitated osteogenesis of a larger number of stem cells than the untreated and the hyaluronic acid-coated scaffolds. We demonstrate that gelatin is an appropriate macromolecule for modifying the surface of an electrospun polycaprolactone fibre scaffold that is used subsequently in bone tissue engineering applications.

Cellulose ultrafine fibers embedded with titania particles as a high performance and eco-friendly separator for lithium-ion batteries.

Mixtures of cellulose acetate (M.W. ∼3 × 104 g/mol) dissolved in 75% v/v acetic acid in water (17% w/w) and ground anatase titania particles with diameters of 197 ±â€¯75 nm (0%, 5% and 10% w/w) were electrospun at 17 kV with a fiber collection distance and a feed rate of 10 cm and 0.6 mL/h. Then, the fiber was treated with 0.5 M potassium hydroxide in ethanol. Rough regenerated cellulose (RC)-titania separators with diameters of ∼310 nm and uniformly dispersed titania particles showed ∼78% porosities. They decomposed at 300 °C, higher than the decomposition temperature of polyethylene separators (220 °C). Added titania particles increased the electrolyte wettability and lithium transference number (from 0.22 to 0.62). RC - 10% titania separator retained the capacity with 79 mA h/g after 30 cycles and had excellent discharge capacity. These fascinating properties make RC-titania separator promising for lithium ion battery.

Separation of Oil-in-Water Emulsions Using Hydrophilic Electrospun Membranes with Anisotropic Pores.

It has been challenging to separate oil from oil/water emulsions with droplet size less than 1 µm using conventional porous membranes. Membranes with small pores are preferred, but the trade-off is a dramatic reduction of volumetric flux. Here, we prepared membranes from electrospun polycaprolactone (PCL) fibers with high porosity (∼88%). When the membranes were stretched uniaxially at different strain levels, the pores became anisotropic with an aspect ratio (pore length/width) up to 5.3 ± 3.0. To improve their wettability, we added Tween 80, a hydrophilic surfactant, to PCL solutions for electrospinning. The modified PCL membranes showed excellent mechanical properties with a tensile strength at 6.59 ± 1.67 MPa and the elongation at break up to 130 ± 21%, warranting their use as free-standing separators. We narrowed the pore gap while maintaining the high porosity by stretching the membranes. Scanning electron microscopy (SEM) images of the stretched membranes show changes of pore geometry without altering the fiber size and fiber network integrity with strain up to 80%. The anisotropic membrane could exclude oil from oil-in-water emulsion droplets with a diameter as small as 18 nm without reduction of the volumetric flux in comparison with the nonstretched one.

Titania-functionalized graphene oxide for an efficient adsorptive removal of phosphate ions.

Titania-functionalized graphene oxide (T-F GO), synthesized by a sol-gel process, was used as a highly efficient material to remove phosphate ions from the simulated wastewater. X-ray diffraction spectra, Fourier transform infrared spectra and scanning electron micrographs of T-F GO confirmed that titania particles were successfully grown on graphene oxide (GO) surface. The phosphate ion adsorption capacities of GO, titania and T-F GO as a function of the contact time and the pH were investigated by a UV-visible spectrophotometer. Results showed that T-F GO could absorb phosphate ions better than titania and GO could. This indicated the synergistic effect between titania and GO in the phosphate ion adsorption. The pH increment lowered the absorption capacities due to increasing the repulsion between phosphate anions and the charges on the T-F GO surface, whereas the addition of sodium ions increased the adsorption capacities. Also, phosphate ions were absorbed by specific sites of T-F GO and formed a monolayer on its surface. Finally, the maximum adsorption capacity of T-F GO was 33.11 mg/g at pH 6, much higher than those of GO and titania. Therefore, T-F GO could be a promising material to remove phosphate ions from wastewater in the future.