Xiaoning Mou

Biopolymer/Calcium phosphate scaffolds for bone tissue engineering.

With nearly 30 years of progress, tissue engineering has shown promise in developing solutions for tissue repair and regeneration. Scaffolds, together with cells and growth factors, are key components of this development. Recently, an increasing number of studies have reported on the design and fabrication of scaffolding materials. In particular, inspired by the nature of bone, polymer/ceramic composite scaffolds have been studied extensively. The purpose of this paper is to review the recent progress of the naturally derived biopolymers and the methods applied to generate biomimetic biopolymer/calcium phosphate composites as well as their biomedical applications in bone tissue engineering.

Graphene oxide-reinforced biodegradable genipin-cross-linked chitosan fluorescent biocomposite film and its cytocompatibility

A genipin-cross-linked chitosan/graphene oxide (GCS/GO) composite film was prepared using a solution casting method. Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy of the composite films showed that the interactions between the CS and oxygen-containing groups of GO resulted in good dispersion of the GO sheets in the CS network. The addition of GO decreased the expansion ratio of the composite films in physiological conditions and increased the resistance to degradation by lysozymes in vitro. As well, the tensile strength values of the GCS/GO films were significantly increased with the increasing load of GO. Moreover, the GCS/GO composite film also maintained the intrinsic fluorescence of GCS. The in vitro cell study results revealed that the composite films were suitable for the proliferation and adhesion of mouse preosteoblast (MC3T3-E1) cells. The GCS/GO biocomposite films might have a potential use in tissue engineering, bioimaging, and drug delivery.

Hierarchical hybrid nanostructures of Sn3O4 on N doped TiO2 nanotubes with enhanced photocatalytic performance

Semiconductor nanostructures with photocatalytic activity have many potential applications including remediation of environmental pollutants and photocatalytic hydrogen evolution. An effective way of promoting photocatalytic activity is by creating heterogeneous photocatalysts. In this paper, a hybrid nanostructured photocatalyst with desired three-dimensional (3D) nanoarchitecture by assembling Sn3O4 nanosheets on N-doped TiO2 nanotubes has been constructed with enhanced broad spectrum photocatalytic properties, which can harness UV and visible light to decompose organic contaminants in aqueous solutions and split water to hydrogen. Photocatalytic tests showed that the Sn3O4/N-TiO2 hierarchical hybrid nanostructures possessed a much higher degradation rate of methyl orange and hydrogen evolution rate than that of the unmodified TiO2 nanotubes, N-TiO2 nanotubes, Sn3O4 nanosheets and Sn3O4/TiO2 hybrid nanostructures. The mechanism related to the enhancement of the photocatalytic activity was discussed. Deposition of Sn3O4 nanosheets onto N-TiO2 nanotubes resulted in a dramatic increase in light-induced generation of hydroxyl radicals, superoxides and singlet oxygen, and the production of holes and electrons. This work is the first instance of combining Sn3O4 with N-TiO2, the Sn3O4/N-TiO2 hierarchical hybrid nanostructures show good photocatalytic performance. This study is potentially applicable to a range of 3D hybrid nanostructures with promising applications in photocatalysis and relevant areas.

Effects of Graphene Quantum Dots on the Self-Renewal and Differentiation of Mesenchymal Stem Cells.

The influence of graphene quantum dots (GQDs) on key characteristics of bone marrow derived mesenchymal stem cells (MSCs) phenotype (i.e., self-renewal, differentiation potential, and pluripotency) is systematically investigated in this work. First, the viability and impact of GQDs on the self-renewal potential of MSCs is evaluated in order to determine a threshold for the exposing dose. Second, GQDs uptake by MSCs is confirmed due to the excellent fluorescent properties of the particles. They exhibit a homogenous cytoplasmatic distribution that increases with the time and concentration. Third, the impact of GQDs on the osteogenic differentiation of MSCs is deeply characterized. An enhanced activity of alkaline phosphatase promoted by GQDs indicates early activation of osteogenesis. This is also confirmed upon GQD-induced up-regulation of phenotypically related osteogenic genes (Runx2, osteopontin, and osteocalcin) and specific biomarkers expression (osteopontin and osteocalcin). GQDs also effectively enhance the formation of calcium-rich deposits characteristics of osteoblasts. Furthermore, genes microarray results indicate that the enhanced osteogenic differentiation of MSCs by GQDs is in progress through a bone morphogenetic protein and transforming growth factor-β relative signaling pathways. Finally, intracytoplasmatic lipid detection shows that GQDs can also promote the adipogenic differentiation of MSCs, thus confirming the prevalence of their pluripotency potential.

Surface Charge Regulation of Osteogenic Differentiation of Mesenchymal Stem Cell on Polarized Ferroelectric Crystal Substrate

Polarized ferroelectric crystal lithium niobate wafers with different cuts are selected to offer differently charged surfaces. By induction of the mesenchymal stem cells differentiation into osteoblasts on different charged surfaces, the specific osteogenic-associated markers are assessed and the results illustrate that the positively charged wafer surface enhances rBMMSCs osteogenic differentiation.

Rutile Nanorod/Anatase Nanowire Junction Array as Both Sensor and Power Supplier for High‐Performance, Self‐Powered, Wireless UV Photodetector

Self-powered UV photodetectors based on TiO2 nanotree arrays have captured much attention in recent years because of their many advantages. In this work, rutile/anatase TiO2 (R/A-TiO2 ) heterostructured nanotree arrays are fabricated by assembling anatase nanowires as branches on rutile nanorods. External quantum efficiencies as high as 90% are reached at 325 nm. These high quantum efficiencies are related to the higher amount of light harvesting due to the larger surface area, the better separation ability of the photogenerated carriers by the rutile/anatase heterostructure, and the faster electron transport, related to the 1D nanostructure and lattice connection at the interface of the two kinds of TiO2 . Furthermore, a self-powered wireless UV photodetector is shown with excellent wireless detection performance. Such devices will enable significant advances for next-generation photodetection and photosensing applications.

A Nanostructured Molybdenum Disulfide Film for Promoting Neural Stem Cell Neuronal Differentiation: toward a Nerve Tissue‐Engineered 3D Scaffold

Physical cues from nanostructured biomaterials have been shown to possess regulating effects on stem cell fate. In this study, nanostructured molybdenum disulfide (MoS2) thin films (MTFs) are prepared by assembling MoS2 nanosheets on a flat substrate. These films are used as a new biocompatible platform for promoting neural stem cell (NSC) differentiation. The results show that the nanostructured MTFs exhibit significantly positive effects on NSC attachment and proliferation without measurable toxicity. More importantly, immunostaining and real‐time polymerase chain reaction assessments show that the nanostructured MTFs induce NSC differentiation into neural cells at higher efficiency. It is found that the MTFs have a good electrical conductivity and offer larger surface areas for NSC attachment and spreading compared with conventional tissue culture plates. Furthermore, multilayered cylindrical 3D living scaffolds are constructed by rolling up NSC‐cultured MoS2‐polyvinylidene fluoride (PVDF) nanofiber films that are prepared by chemically assembling MoS2 nanostructures on electrospun PVDF flexible films. These living nerve scaffolds have a great potential for applications in nerve regeneration as cylindrical 3D living scaffolds.