Background: Electrospinning is a simple and effective method for fabricating micro-and nanofiber matrices. Electrospun fibre matrices have numerous advantages for use as tissue engineering scaffolds, such as high surface area-to-volume ratio, mass production capability and structural similarity to the natural extracellular matrix (ECM). Therefore, electrospun matrices, which are composed of biocompatible polymers and various biomaterials, have been developed as biomimetic scaffolds for the tissue engineering applications. In particular, graphene oxide (GO) has recently been considered as a novel biomaterial for skeletal muscle regeneration because it can promote the growth and differentiation of myoblasts. Therefore, the aim of the present study was to fabricate the hybrid fibre matrices that stimulate myoblasts differentiation for skeletal muscle regeneration. Results: Hybrid fibre matrices composed of poly(lactic-co-glycolic acid, PLGA) and collagen (Col) impregnated with GO (GO-PLGA-Col) were successfully fabricated using an electrospinning process. Our results indicated that the GO-PLGA-Col hybrid matrices were comprised of randomly-oriented continuous fibres with a three-dimensional non-woven porous structure. Compositional analysis showed that GO was dispersed uniformly throughout the GO-PLGA-Col matrices. In addition, the hydrophilicity of the fabricated matrices was significantly increased by blending with a small amount of Col and GO. The attachment and proliferation of the C2C12 skeletal myoblasts were significantly enhanced on the GO-PLGA-Col hybrid matrices. Furthermore, the GO-PLGA-Col matrices stimulated the myogenic differentiation of C2C12 skeletal myoblasts, which was enhanced further under the culture conditions of the differentiation media. Conclusions: Taking our findings into consideration, it is suggested that the GO-PLGA-Col hybrid fibre matrices can be exploited as potential biomimetic scaffolds for skeletal tissue engineering and regeneration because these GO-impregnated hybrid matrices have potent effects on the induction of spontaneous myogenesis and exhibit superior bioactivity and biocompatibility.

The progress of the chemical dissolution of porous silicon (PSi) formed from lightly-doped p-type silicon in ethanoic HF solutions was monitored by recording in situ the photocurrent from monochromatic illuminations, which was used as a measure of optical transmission. The relations between dissolution time, porosity, and absorption coefficient were established and the porosity-dependence of the absorption coefficient derived from ∼60% porosity to 100% porosity. The absorption results were discussed considering the Bruggeman model of effective medium approximation and other measurements from the literature, together with the effects of quantum confinement (QC) and surface states. The porosity and spectral dependences of the QC in the absorption spectra were clearly observed. QC in the blue spectral range (<500 nm) was found to require extremely high porosities (>85%), contrary to the red to green region, where QC was identified for the whole porosity range studied. Our procedure allows the continuous exploration of a wide range of porosities, without limitation on the high side, while preserving an ideal hydrogen-terminated PSi surface and very good structural integrity, as PSi is always kept in HF solution and never dried. The study also allows the determination of the dissolution rate of silicon in various HF-based solutions.

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Most of the highly efficient luminescent silicon nanocrystals (SiNCs) reported to date consist of organically capped silicon cores. Here, we report a method of obtaining Si/SiO 2 core/shell nanoparticles emitting at a peak energy of 1.5 eV with very high quantum yields (53-61%). The same method led to quantum yields of ∼30% for porous silicon powder emitting at 1.9 eV. The SiNCs were very stable under continuous excitation for several hours. The lifetime at 1.5 eV was over 232 µs, the longest ever reported for SiNCs, consistent with the very high luminescence efficiency. The SiNCs were first fabricated by non-thermal plasma synthesis or anodization in the case of porous silicon. Then, a thin oxide shell (∼1 nm) was grown using high-pressure water vapor annealing. This oxidation process allows for the growth of very good quality oxide with low defect concentration and low stress, resulting in very good surface passivation, which explains the very high quantum yields obtained.

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