Facile Preparation of Cellulose Beads with Tunable Graded Pores and High Mechanical Strength.

Cellulose-based hierarchical porous beads exhibit significant application potential in adsorption and separation systems due to their degradation and biocompatibility. However, the current fabrications of cellulose beads show poor mechanical properties and a difficult-to-regulate hierarchical porous structure, reducing their lifespan of use and limiting their application in fine separation. Here, we reported the facile creep-drop method to prepare cellulose beads that enabled systemic regulation of the macro-size, micropore structures, and mechanical properties by optimizing injection nozzle diameter, the composition of the coagulation bath, the temperature of the coagulation bath, and cellulose concentration. Notably, during the molding process, the H2SO4-Na2SO4 composite solidification bath endowed cellulose beads with a dense shell layer and a loose core layer, which achieved the integration of mechanical properties and high porosity. The cellulose beads exhibited high porosity (93.38-96.18%) and high sphericity (86.78-94.44%) by modulating the shell thickness of the cellulose beads. In particular, the cellulose beads exhibited excellent mechanical properties with a high compressive strength of 544.24 kPa at a 5% cellulose concentration. It is expected that these cellulose beads with tunable microstructures can realize their potential for applications in the fields of wastewater treatment, chemical engineering, bioengineering, medicine, and pharmaceuticals.

Antibacterial Nanocellulose-TiO2/Polyester Fabric for the Recyclable Photocatalytic Degradation of Dyes.

In this paper, we report an antibacterial, recyclable nanocellulose-titanium dioxide/polyester nonwoven fabric (NC-TiO2/PET) composite for the highly efficient photocatalytic degradation of dyes. The NC-TiO2 was loaded onto the surface of flexible PET nonwoven fabric through a simple swelling and dipping method. The NC-TiO2 in the particle size range of ~10 nm were uniformly attached to the surface of the PET fibers. The NC-TiO2/PET composite has the ability to achieve the stable photocatalytic degradation of dyes and presents antibacterial properties. The degradation rates to methylene blue (MB) and acid red (AR) of the NC-TiO2/PET composite reached 90.02% and 91.14%, respectively, and the inhibition rate of Escherichia coli was >95%. After several rounds of cyclic testing, the photocatalytic performance, antibacterial performance, and mechanical stability of the NC-TiO2/PET composite remained robust.

In situ synthesis of TiO2/NC on cotton fibers with antibacterial properties and recyclable photocatalytic degradation of dyes.

A cotton fabric/titanium dioxide-nanocellulose (TiO2-Cot.) flexible and recyclable composite material with highly photocatalytic degradation of dyes and antibacterial properties was synthesized. During the preparation process, nano-TiO2 particles were synthesized through an in situ strategy and grown on cotton fiber, and were wrapped with cellulose nanocrystals (NC). The prepared TiO2-Cot. was characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The SEM and EDS results showed that nano-TiO2 particles were evenly distributed on the fiber surface. The prepared TiO2@Cot. has excellent photocatalytic efficiency of 95.68% for MB and 92.77% for AR under weak ultraviolet irradiation over 6 h. At the same time, it has excellent antibacterial activity against S. aureus and E. coli. The stability and reusability of the materials were also investigated.

Silk-Waste-Derived Porous Carbon for Fast Electric Heating under Safe Voltage.

Fast and safe electric heating is highly needed in extreme climates or thermal therapy. Herein, porous activated carbon derived from silk waste is prepared by a simple method. Various porous activated carbons are obtained using different types and concentrations of activator (KOH, KCl, and KHCO3). The effect of the microstructure on the electric heating performance of these carbons is investigated carefully. The type, activator concentration, and carbonization temperature play key roles in the regulation of electric heating properties. The porous carbon activated by 0.05 M KHCO3 at 800 °C demonstrates larger specific surface area (3077 m2 g-1), higher graphitization degree, and lower resistance (2.4 Ω cm), which synergistically contribute greatly to its higher electrothermal efficiency and better electric heating performance. The equilibrium temperature could reach 73 °C in 2 min under a safe voltage of 12 V, proving the better pore-forming capacity and activating function of KHCO3. An electric heating cotton@carbon composite fabric with quite good electric heating property and stability is also prepared, which could reach 38 °C in 2 min under 12 V safe voltage and maintain a temperature 10 °C higher than the ambient temperature even when bent at an angle of 55°. This activated carbon derived from waste protein using a simple and cheap process has great potential in practical applications.

In-situ synthesis of Cu2O on cotton fibers with antibacterial properties and reusable photocatalytic degradation of dyes.

In this study, the cotton fabrics/cuprous oxide-nanocellulose (Cu2O-NC) flexible and recyclable composite material (COCO) with highly efficient photocatalytic degradation of dyes and antibacterial properties was fabricated. Using flexible cotton fabrics as substrates, Cu2O were in-situ synthesized to make Cu2O uniformly grew on cotton fibers and were wrapped with NC. The photocatalytic degradation ability of COCO-5 was verified by use methylene blue (MB), the degradation rate was as high as 98.32%. The mechanism of COCO-5 photocatalysis and the process of dye degradation were analyzed by using electron paramagnetic resonance (EPR) spectrum, transient photocurrent response (TPR) spectrum, Fourier transform infrared (FTIR) spectroscopy and ion chromatography (IC). This study analyzed the complete path from electron excitation to dye degradation to harmless small molecules. Qualitative and quantitative experiments demonstrate that COCO-5 has high antibacterial activity against S. aureus and E. coli, the highest antibacterial rate can reach 93.25%. Finally, the stability of COCO-5 was verified by recycling and mechanical performance tests. The textile-based Cu2O functionalized material has photocatalytic degradation and antibacterial properties, and the preparation process is simple and convenient for repeated use, so it has great potential in wastewater treatment containing dyes and bacteria.

Soluble expression and purification of high-bioactivity recombinant human bone morphogenetic protein-2 by codon optimisation in Escherichia coli.

We developed a simple method of preparing recombinant human bone morphogenetic protein-2 (rhBMP-2) with high biological activity. This rhBMP-2 was overproduced in Escherichia coli as a fusion protein with thioredoxin 6xHis-tag at its amino terminus. The cDNA fragment of human bone morphogenetic protein-2 (hBMP-2) fused to the secretion signal of alkaline phosphatase (PhoA) was expressed under T7 promoter in E. coli. After DNA sequence confirmation, the recombinant vector pETpho-bmp2 was transformed into E. coli BL21 (DE3). rhBMP-2 was produced by the recombinant strain pETpho-bmp2/BL21 (DE3) in a soluble form with an yield of 6.2 mg/L culture. Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) results showed that the molecular weight of the product was approximately 28 kD. Moreover, rhBMP-2 was secreted as a dimer with a natural structure. rhBMP-2, purified by Ni Nitrilotriacetic acid Agarose (Ni-NTA) affinity chromatography, was used to examine osteosarcoma MG-63 cells and assay the alkaline phosphatase (ALP) activity. Results showed that rhBMP-2 induced MG-63 cell differentiation. When the final concentration was 500 ng/mL, the effect was more remarkable and ALP activity reached 525% compared with that of the control group.

High-level expression and purification of a molluskan endoglucanase from Ampullaria crossean in Pichia pastoris.

EG27I is an endogenous glucanase belonging to glycoside hydrolase family (GHF) 45 from the mollusk Ampullaria crossean. In this study, the mature EG27I peptide gene fused to the HFBII secretion signal of Trichoderma reesei was expressed under the GAP promoter of Pichia pastoris in SMD1163 strain. A bioactive EG27I with a molecular weight of 27 kDa was successfully expressed and secreted into our culture medium. The respective final OD600 and hydrolytic activity were 333 and 1.28 U/mL when high-cell-density fermentation of the recombinant P. pastoris was performed in a 7.5 L fermenter through a fed-batch strategy for 132 h. The recombinant protein concentration of the fermentation supernatant was 47.7 mg/L. EG27I was consecutively purified from the fermentation supernatant through ultrafiltration, cation exchange, and hydrophobic interaction. The specific activity of the recombinant EG27I was 26.8 U/mg, and the optimal pH and temperature of the enzyme were 5 and 50 °C, respectively. The half-life of the enzyme activity at 100 °C could reach 40 min. The N-terminal amino acid sequence analysis of the purified recombinant protein confirmed that the amino terminal sequence was consistent with the natural structure. The high quantity and purity of the EG27I provide a basis for future structural and functional studies.

Influence of reaction conditions on the self-assembly of the natural silk sericin protein.

In the past years, the self-assembly of specific proteins has been paid more and more attention due to their significant role in human health and fabrication of new materials. In this article, we explore the effect of reaction conditions on the self-assembly of natural silk sericin protein, including the molecular weight and the concentration of sericin, pH, and metal ions in the reaction system. The results indicate that all these factors, especially species and concentration of metal ions, could influence the self-assembly process of the silk sericin protein. A series of assemblies with various morphologies can be fabricated by modulating the reaction condition. The article may provide some clue for the understanding of the protein self-assembly in the body and a method to fabricate new organic materials with different morphology. Microsc. Res. Tech. 80:298-304, 2017. © 2016 Wiley Periodicals, Inc.

Degradation pattern of porous CaCO3 and hydroxyapatite microspheres in vitro and in vivo for potential application in bone tissue engineering.

Despite superior clinical handling, excellent biocompatibility, biodegradation property of calcium phosphate needs to be improved to coincide with the rate of new bone formation. In this study, spherical CaCO3 are fabricated in the presence of the silk sericin and then transformed into porous hydroxyapatite (HAP) microspheres via hydrothermal method. The degradation behavior of obtained CaCO3, HAP and their mixture is first investigated in vitro. The result demonstrates that the weight loss of HAP microspheres are almost 24.3% after immersing in pH 7.40 Tris-HCl buffer solution for 12 weeks, which is far slower than that of spherical CaCO3 (97.5%). The degradation speed of the mixtures depends on the proportion of CaCO3 and HAP. The mixture with higher content of CaCO3 possesses a quicker degradation speed. The obtained CaCO3 and HAP microspheres are injected into subcutaneous tissue of ICR mice with the assistance of sodium alginate. The result in vivo also shows an obvious difference of degradation speed between the obtained CaCO3 and HAP microspheres, implying it is feasible to modulate the degradation property of the mixture through changing the proportion of CaCO3 and HAP The good cytocompatibility of the two kinds of microspheres is proved and a mild inflammation response is observed only at early stage of implantation. The job offers a simple method to modify the degradation properties of biomaterial for potential use in bone tissue engineering.