Yizao Wan

Proliferation and Osteoblastic Differentiation of Human Bone Marrow Stromal Cells on Hydroxyapatite/Bacterial Cellulose Nanocomposite Scaffolds

In this study, we prepared hydroxyapatite/bacterial cellulose (HAp/BC) nanocomposite scaffolds utilizing the biomimetic technique, and investigated the proliferation and osteoblastic differentiation of stromal cells derived from human bone marrow (hBMSC) on them. Scanning electron microscopy proved that cells could adhere and spread on scaffolds. The hBMSC seeded on the nanocomposites exhibited better adhesion and activity than those seeded upon the pure BC. After 6 days of culture on scaffolds, the cells proliferated faster on the nanocomposites than on the pure BC, as assessed by Alamar Blue assay. Real-time reverse transcription PCR results showed that the alkaline phosphatase (ALP) activity of hBMSC and the expression of osteopontin, osteocalcin, bone sialoprotein, and ALP mRNA were all higher for up to 7 days for hBMSC cultured on the nanocomposites than for those cultured upon the pure BC with and without the presence of osteogenic supplements (L-ascorbic acid, glycerophosphate, and dexamethasone, p<0.05). These results suggest that the attachment, proliferation, and differentiation in cultured hBMSC can be modulated by the HAp/BC nanocomposite scaffold properties. In summary, we have developed a scaffold that displays in vitro biocompatibility, which may have potential use for bone tissue engineering.

PREPARATION AND CHARACTERIZATION OF ANTIBACTERIAL VISCOSE-BASED ACTIVATED CARBON FIBER SUPPORTING SILVER

Viscose-based activated carbon fiber supporting silver (ACF(Ag)) was prepared by pretreatment, carbonization, activation, vacuum impregnation and decomposition processes. The ACF(Ag) was characterized by silver content, silver particle size, distribution and antibacterial properties. It was confirmed that the presence of silver decreased the specific surface area of the ACF. The silver content and the surface morphologies of the ACF(Ag) were dependent on initial concentration of AgNO 3 solution, immersion time and decomposition temperature, of which AgNO 3 content was the most important factor. Factors influencing the resistance to attrition of the ACF(Ag) were also discussed in this paper. The ACF(Ag) containing as low as 0.065 wt% of silver exhibited strong antibacterial property against Escherichia coli and Staphylococcus aureus.

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.

Electrodeposition and characterization of Al2O3-Cu(Sn), CaF2-Cu(Sn) and talc-Cu(Sn) electrocomposite coatings

Abstract Electrocomposite coatings consisting of Al 2 O 3 , CaF 2 , talc particles and copper–tin alloy were prepared by means of the conventional electrodeposition technique. The effects of cathode current density, particle concentration in the bath and stir rate on the volume percentage of particles V p in the composite coatings were investigated. It was shown that current density, effective particle concentration in the plating solution instead of particle concentration in the bath and stir rate strongly affected V p . The internal stress of composite coatings was influenced by current density and particle content. The presence of particles greatly improved the hardness and wear resistance of composite coatings. The results of the present studies revealed that internal stress, hardness, wear resistance, and the relationship between V p and current density, particle concentration in the bath and stir rate were dependent on the nature of incorporated particles.

Antibacterial pitch-based activated carbon fiber supporting silver

Pitch-based activated carbon fiber (ACF) supporting silver (ACF(Ag)) was prepared by pre-oxidization, carbonization, activation, immersion and decomposition processes. The structures, surface photographs and functional groups of the ACF and the ACF(Ag) were investigated. The ACF exhibited increased oxygen-containing functional groups and decreased BET specific surface areas after supporting silver particles. The ACF(Ag) with COH, CO, -COOH and -COOAg groups showed strong adsorption and antibacterial activity against E. coli, which suggests it is a promising antibacterial material. However, ways of controlling the distribution of silver-particle size should be found before any practical application.

A general strategy of decorating 3D carbon nanofiber aerogels derived from bacterial cellulose with nano-Fe3O4 for high-performance flexible and binder-free lithium-ion battery anodes

Flexible, binder-free, and cost-effective materials have been highly sought-after in the development of next generation electrodes. Herein, we report a general, scalable, and eco-friendly synthesis of a novel flexible nano-Fe3O4-decorated three-dimensional (3D) carbon nanofiber (CNF) aerogel derived from bacterial cellulose (BC) (named Fe3O4-BC-CNFs) via a hydrothermal approach followed by carbonization. The as-prepared Fe3O4-BC-CNF electrodes with optimal Fe3O4 loading exhibit greatly improved electrochemical performance over bare BC-CNFs and Fe3O4 nanoparticles. Furthermore, compared with most of the other relevant types of electrodes, the flexible and binder-free Fe3O4-BC-CNF electrodes can deliver a higher reversible capacity of 754 mA h g−1 (after 100 cycles at 100 mA g−1). The excellent electrochemical performance is ascribed to the highly dispersed Fe3O4 nanoparticles on CNFs, the 3D porous structure, large surface area, and the interconnected CNFs, which offer a large material/electrolyte contact area, promote a high diffusion rate of Li ions, and accommodate volume changes of the active materials during cycling. The excellent flexibility and high reversible capacity of the electrodes as well as the eco-friendly and scalable process make them promising for the development of flexible energy-storage devices.

A novel three-dimensional graphene/bacterial cellulose nanocomposite prepared by in situ biosynthesis

Graphene has been widely used to reinforce various hydrogels while there is no report on the composite hydrogels of bacterial cellulose (BC) and graphene. In this work, a graphene/BC (GE/BC) nanocomposite hydrogel was prepared by in situ biosynthesis. The morphology and structure of the obtained GE/BC nanocomposite were characterized by SEM, TEM, XRD, and Raman. Results showed that the presence of graphene in the culture medium of BC changed the crystalline structure of BC while the in situ biosynthesis process had no influence on the structure of graphene. It was found that graphene nanoplates were uniformly dispersed in the three-dimensional (3D) BC matrix and tightly bound by BC nanofibers. This unique 3D structure will impart the GE/BC nanocomposite with excellent mechanical, electrical, and biological properties.

Three-dimensional cuprous oxide microtube lattices with high catalytic activity templated by bacterial cellulose nanofibers

We report here on the fabrication of a kind of highly cross-linked network structured cuprous oxide microtube lattices (Cu2O–MTLs) by utilizing a bacterial cellulose membrane as a template. The Cu2O–MTLs showed high specific catalytic activity for methylene blue degradation in the presence of H2O2 under dark conditions.

Constructing a novel three-dimensional scaffold with mesoporous TiO2 nanotubes for potential bone tissue engineering

Three-dimensional (3D) nanofibrous scaffolds for tissue engineering have been widely studied while 3D scaffolds made of nanotubes are rarely reported. Herein, we report a novel 3D porous network-structured scaffold built of mesoporous TiO2 nanotubes. The TiO2 nanotubes were synthesized using the template-assisted sol-gel method followed by calcination. Bacterial cellulose (BC) with 3D network structure was used as the template. TEM observation confirms the formation of tubular TiO2 nanotubes. The as-synthesized TiO2 nanotubes exhibit an average outer diameter of less than 100 nm and mesoporous walls consisting of aggregated TiO2 nanoparticles with a size of around 7 nm. SEM and TEM observations reveal that the TiO2 nanotube scaffold possesses 3D porous network structure and the surfaces of TiO2 nanotubes are rugged with nanotopography. Additionally, the scaffold built of mesoporous nanotubes with a mesopore size of 3.3 nm exhibits an extremely large surface area of 1629 m2 g-1. The capacity of the scaffold to support cell proliferation and osteogenic differentiation was evaluated using CCK-8 assay, alkaline phosphatase (ALP), and calcium content assay. The scaffold shows enhanced cell growth and proliferation and improved ALP activity and mineralization compared to the TCPS (tissue culture plate) control. Furthermore, the ALP activity of the scaffold is as high as a hydroxyapatite-coated nanofibrous scaffold. The enhanced proliferation and osteogenic differentiation of the TiO2 nanotube scaffold is ascribed to the outer surface roughness of TiO2 nanotubes, 3D porous network structure, mesopores, and large surface area.

Facile and scalable production of three-dimensional spherical carbonized bacterial cellulose/graphene nanocomposites with a honeycomb-like surface pattern as potential superior absorbents

Frequent contamination of water by oils and organic solvents necessitates efficient and low cost absorbents. Here, for the first time, a novel nanocomposite of sphere-like carbonized bacterial cellulose (SCBC) and graphene (GE) with a honeycomb-like surface morphology and a three-dimensional (3D) interconnected porous structure was synthesized via a facile and scalable one-pot in situ biosynthesis route under agitated culture conditions followed by carbonization. The as-prepared SCBC/GE nanocomposite was characterized by SEM, TEM, XRD, FTIR, Raman, wettability, and absorption capacity measurements. SEM images reveal that the SCBC/GE nanocomposite exhibits a honeycomb-like surface pattern consisting of ridges and large cavities with an average diameter of around 97 μm. Furthermore, the SCBC/GE nanocomposite has high porosity, large specific surface area, strong hydrophobicity, and good elasticity. Importantly, it shows superior absorption capacities for a wide range of oils and organic solvents (the maximum value reaches 457 times of its own weight), higher than any other CNF-based aerogels reported so far, thus having the potential to be used in the field of environmental protection. Additionally, the underlying absorption mechanisms for oil and organic solvents have been explored.