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Yang J.,Zhejiang University | Liu T.,Zhejiang University | Song H.,Hisun Pharmaceutical Hangzhou Co. | Mao F.,Zhejiang University | And 4 more authors.
Huagong Xuebao/CIESC Journal | Year: 2016

In order to reduce the viscosity of petroleum sludge for oil recovery, a micro-emulsion method was studied based on its rheological behavior. The effects of surfactant, micro-emulsion dosage and composition on the viscosity were discussed. The results indicated that the petroleum sludge could be classified as pseudo-plastic fluid and its strong shear-thinning force was attributed to the high content of solid particles in the petroleum sludge. The rheological behavior of petroleum sludge could be described by the P-L model. The results showed that the micro-emulsion could well mix with petroleum sludge and viscosity of the sludge was reduced by more than 95% by adding 25% micro-emulsion by mass. The maximum viscosity reduction was achieved by using sodium dodecyl benzene sulfonate (SDBS) as single surfactant. A viscosity reduction of 99% was obtained with the composited surfactant of OP-10 and SDBS at a ratio of 2:1. © All Right Reserved.


Liu Y.,East China University of Science and Technology | Zhang W.,East China University of Science and Technology | Deng X.,Hisun Pharmaceutical Hangzhou Co. | Poon H.F.,Hisun Pharmaceutical Hangzhou Co. | And 4 more authors.
Journal of Bioscience and Bioengineering | Year: 2015

Basal medium design is considered one of the most important steps in process development. To optimize chemically defined (CD) media efficiently and effectively for the biopharmaceutical industry, a two-step rational strategy was applied to optimize four antibody producing Chinese hamster ovary (CHO) cell lines. In the first step, 48 of 52 components of our in-house medium were divided into three groups according to their characteristics. In the next step, these groups were optimized by spent medium analysis, response surface methodology and mixture design. Because these steps in our strategy involved dividing medium components into groups and subsequently adjusting the concentration of the components, we termed this medium development strategy "divide and conquer". By applying the strategy, we were able to improve the titers of CHO-S, CHO-DG44 and two CHO-K1 cell lines 1.92, 1.86, 2.92 and 1.62-fold, respectively, in 8 weeks with fewer than 60 tests. This divide-and-conquer strategy was efficient, effective, scalable and universal in our current study and offered a new approach to CD media development. © 2015.


Xie P.,East China University of Science and Technology | Niu H.,East China University of Science and Technology | Chen X.,East China University of Science and Technology | Zhang X.,East China University of Science and Technology | And 6 more authors.
Applied Microbiology and Biotechnology | Year: 2016

Charge variants, especially acidic charge variants, in recombinant monoclonal antibodies are critical quality attributes, which can affect antibodies’ properties in vitro and in vivo. Meanwhile, charge variants are cumulative effects of various post-translational modifications and chemical degradations on antibody. In this work, to investigate the effect of lowering culture pH in the stationary phase on acidic charge variant contents in fed-batch cultures and its mechanism, cell culture experiments in 2-L bioreactors were firstly performed to explore the changes in the charge distribution under the pH downshift condition using weak cation exchange chromatography. It is found that acidic charge variant contents were significantly decreased by pH downshift. Then, to reveal the mechanism by which the content of acidic charge variants is reduced under pH downshift condition, the variation of post-translational modifications and chemical degradations under the pH downshift condition was explored. Meanwhile, the structure of the acidic charge variants was characterized. Several analysis experiments including size exclusion chromatography, capillary electrophoresis-sodium dodecyl sulfate under non-reducing conditions, tryptic peptide map, and reduced antibody mass were applied in this study. The results show that the mechanism by which the content of acidic charge variants is reduced is that the contents of disulfide bond reduction, galactosylation, and asparagine deamination of the HC-N388 in the Fc domain were reduced by pH downshift. © 2016 Springer-Verlag Berlin Heidelberg


PubMed | East China University of Science and Technology and Hisun Pharmaceutical Hangzhou Co.
Type: Journal Article | Journal: Applied microbiology and biotechnology | Year: 2016

Charge variants, especially acidic charge variants, in recombinant monoclonal antibodies are critical quality attributes, which can affect antibodies properties in vitro and in vivo. Meanwhile, charge variants are cumulative effects of various post-translational modifications and chemical degradations on antibody. In this work, to investigate the effect of lowering culture pH in the stationary phase on acidic charge variant contents in fed-batch cultures and its mechanism, cell culture experiments in 2-L bioreactors were firstly performed to explore the changes in the charge distribution under the pH downshift condition using weak cation exchange chromatography. It is found that acidic charge variant contents were significantly decreased by pH downshift. Then, to reveal the mechanism by which the content of acidic charge variants is reduced under pH downshift condition, the variation of post-translational modifications and chemical degradations under the pH downshift condition was explored. Meanwhile, the structure of the acidic charge variants was characterized. Several analysis experiments including size exclusion chromatography, capillary electrophoresis-sodium dodecyl sulfate under non-reducing conditions, tryptic peptide map, and reduced antibody mass were applied in this study. The results show that the mechanism by which the content of acidic charge variants is reduced is that the contents of disulfide bond reduction, galactosylation, and asparagine deamination of the HC-N388 in the Fc domain were reduced by pH downshift.

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