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Wang J.,East China University of Science and Technology | Liu C.,State Key Laboratory of Bioreactor Engineering | Liu Y.,East China University of Science and Technology | Zhang S.,East China University of Science and Technology
Advanced Functional Materials | Year: 2010

A major obstacle to the development of a more efficient calcium phosphate bone cement (CPC) is its relatively low mechanical strength and susceptibility to brittle fracture. Herein, a series of dual-setting hybrids have been developed based on the in situ crosslinking polymerization of glycidyl methacrylate derivatized dextran (Dex-MA) and the synchronous hydration process of CPC. Such a strategy is highly desirable for bone regeneration and provides insight into hybrid cement designing. The structure and physical properties of the resulting hybrids are investigated. Compared with CPC, the initial setting time is shortened and may be modulated. As a result, the hybrid cement possesses characteristics of both of its components, and is tunable from stiff-but-not-brittle to ductile-but-not-soft depending on the composition of the double network. Introduction of the polymeric moiety does not obstruct the fundamental hydrating process of CPC. Due to the synergistic effect produced by the double-network structure, the resulting hybrid has an optimal compressive strength of over 98.3 MPa. The mass ratio of the binary network and the size of apertures are shown to be key parameters for improving the compressive strength. An interpenetrating double-network is introduced into calcium phosphate bone-based bone cement via in situ polymerization and hydration. The rigid inorganic cement is responsible for strength while the soft and relaxed hydrogel moiety acts as an energy-absorber. As a result, an improved, mechanically strong bone cement is obtained via the double-network strategy. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Naqvi S.H.A.,National Institute for Biotechnology and Genetic Engineering NIBGE | Dahot U.D.,National Institute for Biotechnology and Genetic Engineering NIBGE | Khan Y.K.,University of Sindh | Xu J.H.,State Key Laboratory of Bioreactor Engineering | Rafiq M.,National Institute for Biotechnology and Genetic Engineering NIBGE
Pakistan Journal of Botany | Year: 2013

The sugar cane industry residue/waste such as sugar cane bagasse contains complex lignocellulosic material, which can be used as an ideal and low cost carbon and energy source for the growth of microbes and production of microbial metabolites under submerged fermentation after pretreatment process. The sugar cane bagasse was pretreated with acid/base (0.3N and 0.6N H2SO4, NH4OH; 2.5% and 5.0% H2O2) to fermentable sugars. These fermentable sugars were used with mineral medium for the growth of Aspergillus fumigatus and production of industrially important enzyme lipase. Aspergillus fumigatus secreted maximum production of lipase 40.0 U/ml at 48 hours cultivation time, when it was grown on city sugar cane bagasse hydrolysate (pretreated with 0.6N NH4OH) mineral medium in comparison to industrial bagasse and other acid/base hydrolyzed sugar cane bagasse. The final pH of culture broth, reducing sugar and lipase activity were checked from fermented medium. Source


Jia H.-J.,State Key Laboratory of Bioreactor Engineering
Chinese Journal of Biologicals | Year: 2014

Objective To investigate the relationship between microcarrier concentration and inoculum density of Madin-Darby canine kidney (MDCK) cells as well as their effects on cell growth. Methods Four ranges of cell counts around a single microcarrier, 0 ~ 10, 10 ~ 20, 20 ~ 60 and 60 ~ 120, were designed. To control the cell counts at the four designed ranges, the microcarrirer concentrations were designed as 12, 7, 3 and 1 g/L, while the inoculum densities of MDCK cells as 5 x 104, 1 x 10s, 5 x 103 and 1 x 106 cells/ml, respectively. All the inoculum densities of MDCK cells for various microcarrier concentrations were 2 x 10s. cells / ml, while all the microcarrirer concentrations for various inoculum densities were 3 g/L. The cells were culture in spinners, from which samples were taken every 24 h, counted and tested for metabolism. MDCK cells were inoculated at optimal density and cultured at optimal microcarrier concentration for 72 h, to which influenza virus A/PR8/34 strain was inoculated at a MOI of 0. 01 and determined for HA titer. Results When the cell count around a microcarrier was controlled at 20-60, the microcarrier concentration was 3 g/L, and the inoculum density of 5 x 10s cells/ml, the viable cell density (VCD) reached more than 3 x 106 cells/ml. The cell growth entered to a stable platform period after culture for 72 ~ 96 h, in which the nutrients such as glucose were not consumed excessively or even exhausted, while the accumulation of metabolic by-products such as lactic acid and ammonia showed relatively low pressure to the culture environment. The condition was beneficial to the inoculation of influenza virus, under which the VCD may reach more than 60% of the theoretical maximum, and the HA titer may reach 12 log2HA unites/50 μl. Conclusion When the cell counts around a single microcarrier was controlled at 20 ~ 60, both the cell growth and metabolism were superior to those under other conditions. The condition was beneficial to the virus replication and increase of virus titer, which provided a reference for large-scale production of MDCK cells-based influenza vaccine. Source


Ding Q.,State Key Laboratory of Bioreactor Engineering | Ou L.,State Key Laboratory of Bioreactor Engineering | Wei D.,State Key Laboratory of Bioreactor Engineering | Wei X.,Shanghai Puchen Biotechnology Co.
Nucleosides, Nucleotides and Nucleic Acids | Year: 2011

Recombinant E. coli pDEOA was constructed and lactose can be used instead of IPTG to induce the expression of thymidine phosphorylase by pDEOA. The use of lactose at concentrations higher than 0.5 mmol/L had an induction effect similar to that of IPTG but resulted in a longer initial induction time and better cell growth. The thymidine phosphorylase induced by lactose was very stable at 50C. Intact pDEOA cells induced by lactose can be used as a source of thymidine phosphorylase. Under standard reaction conditions, several deoxynucleosides were effectively produced from thymidine. Copyright © Taylor and Francis Group, LLC. Source


Huang D.,State Key Laboratory of Bioreactor Engineering | Zhao L.,State Key Laboratory of Bioreactor Engineering | Tan W.,State Key Laboratory of Bioreactor Engineering
Shengwu Gongcheng Xuebao/Chinese Journal of Biotechnology | Year: 2011

In recent years, there are tremendous economic and social losses across the world because of virus-related diseases. It is well known that Madin-Darby canine kidney (MDCK) cells are easily handled, quickly amplified and efficiently infected with influenza virus. Therefore, they are considered as one of the most important cell lines for the production of influenza vaccine. In this work, we first developed a serum-free adherent culture process for MDCK cells with an in-house prepared serum-free medium MDCK-SFM. Next, we derived a cell line named ssf-MDCK, which was amenable for single-cell suspension culture in the serum-free medium. We found that during serum-free batch culture of MDCK cells, the peak viable cell density and maximum specific growth rate were 3.81×106 cells/mL and 0.056 h-1, respectively; 3.6- and 1.6-fold increase compared with those in serum-containing adherent batch culture. In addition, we compared growth and metabolic characteristics of MDCK cells in serum-containing adherent culture, serum-free adherent culture and serum-free single-cell suspension culture. We found that less metabolic by-products were produced in both serum-free cultures. In serum-free single-cell suspension batch culture, the viable cell density was highest. These results are critical for establishing large-scale suspension culture of MDCK cells as subsequent well as large-scale influenza vaccine production. © 2011 CJB, All rights reserved. Source

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