Ruisong Guo

One-Step In Situ Biosynthesis of Graphene Oxide–Bacterial Cellulose Nanocomposite Hydrogels

Graphene oxide-bacterial cellulose (GO/BC) nanocomposite hydrogels with well-dispersed GO in the network of BC are successfully developed using a facile one-step in situ biosynthesis by adding GO suspension into the culture medium of BC. During the biosynthesis process, the crystallinity index of BC decreases and GO is partially reduced. The experimental results indicate that GO nanosheets are uniformly dispersed and well-bound to the BC matrix and that the 3D porous structure of BC is sustained. This is responsible for efficient load transfer between the GO reinforcement and BC matrix. Compared with the pure BC, the tensile strength and Youngs modulus of the GO/BC nanocomposite hydrogel containing 0.48 wt% GO are significantly improved by about 38 and 120%, respectively. The GO/BC nanocomposite hydrogels are promising as a new material for tissue engineering scaffolds.

Surface controlled calcium phosphate formation on three-dimensional bacterial cellulose-based nanofibers

Studies on the early calcium phosphate (Ca-P) formation on nanosized substrates may allow us to understand the biomineralization mechanisms at the molecular level. In this work, in situ formation of Ca-P minerals on bacterial cellulose (BC)-based nanofibers was investigated, for the first time, using the X-ray absorption near-edge structure (XANES) spectroscopy. In addition, the influence of the surface coating of nanofibers on the formation of Ca-P minerals was determined. Combined with XRD analysis, XANES results revealed that the nascent precursor was ACP (amorphous calcium phosphate) which was converted to TCP (β-tricalcium phosphate), then OCP (octacalcium phosphate), and finally to HAP (hydroxyapatite) when phosphorylated BC nanofibers were the templates. However, the formation of nascent precursor and its transformation process varied depending on the nature of the coating material on nanofibrous templates. These results provide new insights into basic mechanisms of mineralization and can lead to the development of novel bioinspired nanostructured materials.

Preparation and properties of a novel porous poly(lactic acid) composite reinforced with bacterial cellulose nanowhiskers

In this work, rod-like bacterial cellulose nanowhisker (BCNW) was produced by sulfuric acid hydrolysis and then a porous polylactic acid (PLA) composite reinforced with 5 wt% BCNW was prepared by solvent casting and freeze drying. The morphology of BCNW and BCNW/PLA composite was observed by TEM and SEM. In addition, mechanical properties, wettability, and water absorption of the composite were examined. It is demonstrated that the incorporation of BCNW in PLA improves the pore structure and porosity. The BCNW/PLA composite shows significantly higher water uptake and hydrophilicity with respect to PLA. Mechanical testing reveals significant improvements in tensile strength and modulus and compressive strength and a decrease in strain at break as compared to neat PLA. The porous BCNW/PLA composite may find applications in the fields of tissue engineering and drug delivery.

Microstructural characterisation and corrosion behaviour of electroless Ni-W-P deposits of mixed nanocrystalline/amorphous structures

Abstract An investigation has been undertaken of the influence of the mixed nanocrystalline and amorphous microstructure on the corrosion behaviour of electroless Ni–5·5W–6·5P (wt-%) deposits on steel substrates. The effects of annealing temperature on microstructure evolution were investigated. The corrosion behaviour of the deposits was evaluated by potentiodynamic polarisation in 0·5M H2SO4 solution and EIS measurements in 3·5%NaCl solution. Relationships between the microstructure and corrosion mechanisms of the as plated and the annealed deposits were considered by reference to microstructural information, including degree of crystallisation, grain sizes of both nickel and Ni3P phases, porosity development, microstrains and residual stresses.

Controlled Synthesis and Photocatalytic Performance of Au@ZnO Nanospheres with Core–Shell and Yolk-Shell Structures Assisted by Carbonaceous Layers as Intermediate

Au@ZnO nanospheres with controlled core-shell and yolk-shell features were successfully fabricated through a facile template-based solvothermal method using carbonaceous layers as intermediate. The active carbonaceous layers containing numerous surface functional groups such as OH and C═O play key roles in fabrication of the Au@ZnO nanospheres. The structures of Au@ZnO can easily controlled by adjusting the concentration of Zn ions aqueous solution and/or the size of Au@C microspheres. The synthesis strategy proposed in this paper is also verified to be suitable for fabricating some other Au@metallic oxides nanospheres such as Au@SnO2 and Au@Fe2O3 with controlled structures. Furthermore, due to the synergic effect of the surface plasma resonance effect of Au cores and the large surface area of 122.67 m2 g-1, the Au@ZnO nanospheres with yolk-shell feature exhibite good photocatalytic activity and stability under visible-light irradiation.