Advanced Materials Research Vols. 550-553

Abstract: Liposome has proven a promising carrier for its special structure and characterization, and can be widely used in pharmacy and cosmetics. Supercritical reverse phase evaporation (SRPE) is a new technique for preparation liposomes with supercritical fluid instead of organic solvent. It features that the preparation process is simple and a high coating ratio is obtained for water-soluble substances. In this paper, the technique was used to synthesize liposomes with water soluble glucose and the effects of the processing technologies parameters on the particle size and the coating ratio of liposomes which were investigated in detail. The liposomes with a volume average diameter of 290-330nm were successfully prepared by this technique and the coating ratio for water-soluble glucose was as high as 27.3%, while it was only 12.5% by the process of physical dispersant in water. It was confirmed that the temperature, pressure and equilibrium time had great effects on the particle size and the coating ratio. As the temperature increased from 35°C to 65°C, the particle size decreased obviously to its minimum value and then changed begins to increase . With the pressure increased from 10MPa to 30MPa, the particle size first decreased and then kept approximately constant. As the equilibrium time increased from 15min to 45min, the particle size first kept an approximately constant value and then increased greatly. Increasing either the temperature from 35°C to 65°C or the pressure from 10MPa to 20MPa, the coating ratio increased remarkably, but it decreased as the pressure increased from 20MPa to 25MPa.

Abstract: To investigate the chemical constituents from the Boehmeria macrophylla Hornem. the chemical constituents were isolated by various column chromatographic methods and their structures were elucidated as β-sitosterol（1）, β-sitosterol glucoside（2）, ursolic acid（3）, 7-hydroxy-6-methoxycoumarin（4）, emodin（5）, cinnamic acid（6）, sweroside（7）, Genistein（8）, all the Compounds were isolated from this plant for the first time.

Abstract: In this study, a hyper-thermostable lipase whole-cell biocatalyst has been developed. The hydrolytic activity of the codon-optimized ROL displayed on the yeast cell surface was 19.5 U /g dried cells cultured in SD medium, while the biomass was 13 g/L. Moreover, the whole-cell biocatalyst presented great thermostability. After 10 min incubation at 90 °C, 95 °C and 100 °C, the residual activity of lipase still remained 89%, 86% and 68%, respectively. Therefore, the whole-cell biocatalyst was applied in bioconversion of FAME and biodiesel. In our study, 50 mM oleic acid was most reasonable for bioconversion of FAME, and 50 mM soy oil was most reasonable for bioconversion of biodiesel, when the reaction were carried out in hexane as the solvent, and the molar ratio of oleic acid (or soy oil) and methanol was 1:4. Reactions were catalyzed by 0.5 g lyophilized bioimprinted whole-cell biocatalyst and incubated at 45 °C for 12 h with shake.

Abstract: In the paper, we investigated the adsorption of nickel by nickel-resistant strain screened in our laboratory. Results indicated that at the following conditions: pH=6, initial concentration of Ni2+ was 25mg/L, mass concentration of bacterial strain was 3g/L, adsorption approach an equilibrium after 2h，and Ni2+ removal reached up to 98.2%. Simulation of adsorption by thermodynamic models revealed that Langmuir equation can describe the adsorption process well, which showed that the adsorption was carried out mainly by means of surface adsorption. AFM detections indicated that the mycelium showed a tendency of shrinking and assembling after the adsorption, which illustrated that the adsorption mainly occurred on the surface. Meanwhile, the surface adsorption can not rule out a certain extent, affect the joint adsorption occurs in the intracellular. After Ni2+ entered the extracellular polymers and even inside the cells, the adsorption was controlled, especially in the later period.

Abstract: In this paper, rice straw (RS) and rice straw ash (RSA) were employed to synthesize mesoporous molecular sieves MCM-41 in an open-vessel. The structure of as-synthesized MCM-41 was characterized by X-ray diffraction (XRD) pattern, Fourier transform infrared (FT–IR) spectrum, NH3-Temperature Programmed Desorption (TPD), and N2 adsorption-desorption isotherms. RS-MCM-41 and RSA-MCM-41 possess the same typical hexagonal mesoporous structure with high long-range order and crystalline degree as those of MCM-41 from water glass (SDS-MCM-41).

Abstract: A comparative study was made of lipozyme TL IM-catalyzed regioselective acylation of 6-azauridine with vinyl palmitate for the preparation of the 5'-O-monoester in co-solvent mixtures and pure polar solvents. Among the solvent systems investigated, a co-solvent mixture of anhydrous acetone/isooctane was found to be the best reaction medium, in which Lipozyme TL IM also exhibited good thermal and operational stability. It was also found that the acylation was dependent on the hydrophobic solvent content. The most suitable co-solvent was anhydrous acetone/isooctane (90:10, v/v). Under the optimal conditions, the initial rate, substrate conversion and 5'-regioselectivity were 20.6 mM/h, 99.0% and 99%, respectively.

Abstract: Feathers, as a waste, are produced in large quantities from poultry processing industry every year. In this paper, feathers were biodegraded by Stenotrophomonas maltophilia DHHJ which was isolated from soil samples. The results show that the optimal conditions for the feather degradation and the keratinase production are 2.5% feather as substrate, the initial pH of 7.8 and cultivation at 40 °C for 5 days. Salts, KCl and NaCl, can increase feather degradation slightly. The proper concentration of Tween 80 can enhance keratinase production significantly. EDTA, as a metalloprotease inhibitor, greatly inhibits keratinolytic activity.

Abstract: Homogeneous modification of sugarcane bagasse with succinic anhydride (SA) was investigated in novel solvent systems ionic liquid 1-butyl-3-methylimidazolium chloride/dimethyl sulfoxide ([C4mim]Cl/DMSO) and dimethyl sulfoxide/N-methylimidazole (DMSO/NMI), respectively. The results showed that succinoylation of SCB with SA was accomplished in [C4mim]Cl/DMSO at high temperature and in DMSO/NMI at room temperature without any additional catalysts. Increasing SA/SCB mass ratio from 2:1 to 3:1 and 4:1 resulted in an improvement of WPG from 21.1 to 29.6 and 30.4 in [C4mim]Cl/DMSO at 120oC, and from 97.3 to 102.5 and 118.4 in DMSO/NMI at room temperature, respectively. The high succinoylation efficiency in DMSO/NMI at room temperature was probably due to the special role of NMI as a solvent, a base and a catalyst in this solvent system. FT-IR and CP/MAS 13C-NMR analyses also provided evidences of succinoylation reaction of SCB with additional catalysts in [C4mim]Cl/DMSO and in DMSO/NMI. The results indicated that the succinoylation of lignin and carbohydrates all occurred.

Abstract: HBUT-C,engineered by Escherichia coli W, was constructed as a new biocatalyst for the production of D-lactate.The strain can grow well in mineral salts medium.HBUT-C completed the fermentation of 10% glucose in 64h to produce 834 mmol·L^-1 lactate of fermentation broth with volumetric productivity of 1.16g·L^-1·h^-1. The optical purity of D-lactate was higher than 98.3%. It was also found that HBUT-C with inactivate genes encoding competing pathways produced 58.9 mM acetate, traces of formate and succinate by-product under anaerobic conditions.

Abstract: Porcine acellular dermal matrix (pADM) was modified by N-(2-Hydroxy) propyl-3-Trimethyl Ammonium Chitosan Chloride (HTCC) with varied concentration, pH, time and temperature. The absorption of HTCC, surface state, hydrophilicity, antibacterial properties and cytotoxicity of pADM were researched before and after modification. Results show that the optimum experimental condition of modification is pH 6.4, 37°C, treated for 48 hours, and the concentration of HTCC 0.7%. The contact angle of modified pADM reduces and the water absorption ratio increases, but the tensile strength and moisture permeability falls. Obvious antibacterial action is observed on Escherichia Coli and Staphylococcus Aureus, and cytotoxicity is grade 2. This work suggests the feasibility of HTCC to modify pADM.