采用浊度法检测聚丙烯酰胺

采用浊度法检测聚丙烯酰胺(HPAM)的质量浓度,考察了反应时间、波长、温度及矿化度对吸光度的影响。实验结果发现:最佳测试条件为反应时间25 min,波长472 nm,温度18～25℃;一价金属离子Na+,K+和二价金属离子Mg2+,Ca2+对测试结果基本无影响,而三价Al3+对吸光度有很大的影响,当ρ(Al3+)大于80 mg/L时,吸光度值趋于稳定。在最佳测试条件下,绘制不同水质条件下不同ρ(HPAM)的标准曲线,发现水质不同,对吸光度的影响不同,矿化度越高吸光度的变化值越大。因此,在检测油田注入、采出液中ρ(HPAM)时,可通过模拟实测水样配制反应体系溶液进行测定。研究表明,用浊度法检测ρ(HPAM)范围宽、精确度高、重现性好。

软基质力学特性对滑膜间充质干细胞向软骨细胞分化的干预作用

背景:课题组前期研究表明,较软的培养基质对大鼠骨髓间充质干细胞的形态及细胞骨架有明显的影响。目的:探讨不同弹性模量的聚丙烯酰胺凝胶软基质对人滑膜间充质干细胞向软骨细胞分化的影响。方法:无菌条件下获取骨关节炎患者滑膜组织,有限稀释法获得原代人滑膜间充质干细胞,流式细胞术进行细胞表面标记物鉴定,多向诱导分化实验进行功能鉴定。用丙烯酰胺和甲叉双丙烯酰胺制备0.4,6,30 kPa3个弹性模量的聚丙烯酰胺凝胶软基质作为培养人滑膜间充质干细胞的基底,在转化生长因子β1存在的情况下分别培养7 d和14 d,RT-PCR方法检测软骨形成相关基因COL2A1、CRTAC1 mRNA的表达,以6孔细胞培养板作为对照组。结果与结论:在不同弹性模量上生长的人滑膜间充质干细胞表现出不同的细胞形态;软基质的弹性模量及培养时间对人滑膜间充质干细胞成软骨基因COL2A1、CRTAC1的表达有交互作用:7 d时,CRTAC1 mRNA在6 k Pa弹性模量聚丙烯酰胺凝胶上表达量最高(F=44.350,P=0.000);7 d时,COL2A1 mRNA在0.4 k Pa弹性模量聚丙烯酰胺软基质上的表达量最高(F=6.384,P=0.005)。较低弹性模量的聚丙烯酰胺凝胶软基质比常规细胞培养板更具有促进滑膜间充质干细胞向软骨细胞分化的作用。

Plant Proteomics in the Post-genomic Era

Proteomics is one of the most active research fields in the post-genomic era. Here we briefly introduce the scientific background of the origination of proteomics and its content, research method. The new developments of proteomics at the levels of individual plants, tissues, organs and organells, as well as its applications in the area of plant genetic diversity, mutant characterization, and plant physiology, etc are reviewed. At last, the challenge and prospect of proteomics are discussed.

Studies on the Quality of Recombinant Human GrowthHormone

The quality of r-hGH has been appraised by various analytical techniques in-cluding SDS-PAGE, IEF. HPSEC, RP-HPLC, ELISA. Dot-immunobinding assay, DIG labeling DNAhybridization and bioassay The results shouwed that the quality of the domestic products of r-hGHreached the international level.

Comparative proteomics analysis of human gastric cancer

AIM: To isolate and identify differentially expressed proteins between cancer and normal tissues of gastric cancer by two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). METHODS: Soluble fraction proteins of gastric cancer tissues and paired normal tissues were separated by 2-DE. The differentially expressed proteins were selected and identified by MALDI-TOF-MS and database search. RESULTS: 2-DE profiles with high resolution and reproducibility were obtained. Twenty-three protein spots were excised from sliver staining gel and digested in gel by trypsin, in which fifteen protein spots were identified successfully. Among the identified proteins, there were ten over-expressed and five under-expressed proteins in stomach cancer tissues compared with normal tissues. CONCLUSION: In this study, the well-resolved, reproducible 2-DE patterns of human gastric cancer tissue and paired normal tissue were established and optimized and certain differentially-expressed proteins were identified. The combined use of 2-DE and MS provides an effective approach to screen for potential tumor markers.

A Temperature-sensitive Hydrogel Refolding System: Preparation of Poly(N-isopropyl acrylamide) and Its Application in Lysozyme Refolding

Temperature-sensitive hydrogel—poly(N-isopropyl acrylamide) (PNIPA) was prepared and applied to protein refolding. PNIPA gel disks and gel particles were synthesized by the solution polymerization and inverse suspension polymerization respectively. The swelling kinetics of the gels was also studied. With these prepared PNIPA gels, the model protein lysozyme was renatured. Within 24h, PNIPA gel disks improved the yield of lysozyme activity by 49.3% from 3375.2U·mg^-1 to 5038.8U·mg^-1. With the addition of faster response PNIPA gel beads, the total lysozyme activity recovery was about 68.98% in 3h, as compared with 42.03% by simple batch dilution. The novel refolding system with PNIPA enables efficient refolding especially at high protein concentrations. Discussion about the mechanism revealed that when PNIPA gels were added into the refolding buffer, the hydrophobic interactions between denatured proteins and polymer gels could prevent the aggregation of refolding intermediates, thus enhanced the protein renaturation.

Isolation of Lysozyme from Chicken Egg White Using Polyacrylamide-based Cation-exchange Cryogel

An effective cation-exchange chromatographic method for lysozyme isolation from chicken egg white is presented, using supermacroporous cryogel grafted with sulfo functional groups. The chromatographic processes were carried out by one-step and sequential elution, respectively. Sodium phosphate buffer （pH 7.8） containing different concentrations of NaC1 is used as elution agent. The corresponding breakthrough characteristics and elution behaviors in the cryogel bed were investigated and analyzed. Purity of lysozyme in the elution effluent was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE）. The maximum purity of the obtained lysozyme was about 96%, and the cryogel is demonstrated as a potential separation medium for purification of high-purit lysozyme from chicken egg white.

Experimental study on slime water flocculation sediment based on the montmorillonite hydration expansion inhibition

Through the montmorillonite settlement experiment in the clear water and electrolyte solution, the influence of slime water settling character was studied in clear water and different electrolyte solution, the montmorillonite＇s hydration ex- pansion effectively restrained was verified, the process method to wash coal with the electrolyte was put forward, and the re- sults indicate that the solution of 10 g/L KC1 is optimal inhibitor on the montmorillonite in the tested three kinds of electrolyte solution. With the contrast test in clear water and electrolyte solution, two reagent adding way can be selected in KC1 solution： one way is to add PAM separately, the effectively sedimentation can be made with simply 0.1% anion; the other way is the co- ordination with polymeric aluminum and PAM, the anionic of PAM and polymeric aluminum are 0.02% and 0.5% respectively. However, in clear water, the polymeric aluminum must be joined together with the anionic PAM, and the amount of the PAM reaches 0.5%, which is 25 times as great as that in KCL solution. The field work with raw coal further verifies the above con- clusions further.

Swelling properties and molecular simulation of PNIPA porous hydrogels

A series of porous intelligent hydrogels, which exhibited appropriate lower critical solution temperature (LCST) and fast response behavior, were synthesized by radiation method. The structure and surface morphology of hydrogels were examined by the infrared radiation and the scanning electron microscopy, respectively. The influences of the content of crosslinking agent and relative molecular mass of polyethylene glycol (PEG) on the swelling properties of hydrogels were discussed. The molecular mechanics simulations were performed to investigate the phase transformation mechanism of poly(N-isopropyl acrylamide) (PNIPA) hydrogel. The results show that macropores are observed in hydrogels, whereas hydrogels prepared without using PEG have a dense surface. LCST of hydrogels increases with the increase of relative molecular mass of PEG. The swelling mechanism of PNIPA porous hydrogels follows non-Fickian diffusion model. The theoretical maximum water absorption S∞ is approximately consistent with experimental value according to the second-order kinetics model established by Schott. The molecule chains of PNIPA hydrogel begin folding and curling, resulting in volume shrinkage at 305 K. There are much intramolecular nonbonding interactions in molecule chains of hydrogels. The porous hydrogels are expected to be applied in the field of artificial intelligence material.

Colorectal carcinoma-associated antigen Ca-Hb3 detected by one-dimensional SDS-polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectrometry

AIM: To comprehensively identify the proteins of tumor relative antigen Ca-Hb3 recognized by colorectal carcinoma monoclonal antibody Hb3. METHODS: Ca-Hb3 was isolated by SDS-polyacrylamide gel electrophoresis (PAGE) followed by digestion with trypsin. Trypsin peptides were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/ MS). The proteins identified by mass spectrometry were analyzed using bioinformatics. RESULTS: Ca-Hb3 was identified as a CKAP4-like protein by Nano HPLC tandem mass spectrometry analysis. The molecular weight of CKAP4-like protein was 62.02 kDa, including one hydrophobic region, one transmembrane domain, five coiled coils, four glycosylation sites and forty-nine phosphorylation sites. CKAP4-like protein had a high homogeneity with DeltaNp63α. The characteristic expression of DeltaNp63α that is considered a potential oncogene in the isoforms of p63 was similar to that of Ca-Hb3. CONCLUSION: Ca-Hb3 is probably a CKAP4-like protein, belonging to DeltaNp63α isoform of p63 family.

Rheological behavior of hydrolyzed polyacrylamide solution flowing through a molecular weight adjusting device with porous medium

The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer so- lution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sandstone reservoirs in EOR projects. To alleviate the matching problems between the layer permeability and the injected polymer molecular weight, a molecular weight adjusting device with porous medium was designed on the basis of mechanical degradation principle. In terms of four variables （polymer concentration, pore diameter, length of shear component and flow rate ）, the theological behavior of hydrolyzed polyacrylamide （HPAM） solu- tion flowing through the device was investigated in detail. The change of these variables is able to control the shear rate of HPAM solutions through ceramic foam, and achieve the desired degree of shear degradation and the final theological parameters-viscosity loss, viscoelasticity and pressure drop. Therefore, a linear relationship between viscosity loss and shearing rate was established so as to obtain the targeted viscosity easily. Field tests in the Daqing Oil Field showed that the polymer molecular weight could drop 20% to 50%. In a word, the results could guide the industrial application of the novel device and the further study of polymer degradation flowing through the porous medium.

The Research of Complex System Property between Thermosensitive Polymer and Surfactant

In this paper, the rigid structural thermosensitive polymer （made in lab） of NBS （N-butyl styrene）, N, N-DEAM （diethyl acrylamide） and AM （acrylamide） was prepared. The influence of viscosity for copolymer solution under different reaction conditions such as temperatures and inorganic salt （monovalent salt and divalent salt） was analyzed. The experiment studies the combination of polymer situation and three different types of surfactants under certain conditions of the room temperature （25℃） and the formation temperature （76℃）. At last, the influence of the surfactant kinds and concentration on the viscosity of the polymer solution are studied. The results show that： The copolymer solution, the apparent viscosity of which decreases with the increasement of temperature, but its viscosity has suddenly increased and thereafter dropped in the transition temperature. So the temperature sensitive effect ofcopolymer is very significantly. When the concentration of inorganic salt and surfactant can be controlled in certain extent, the copolymer solution, the effect increases with the increasement of the concentration, but the viscosity of which decreases with the increasement of shear rate. Shear rate can be controlled in certain extent, shearing stability properties of the copolymer solution are proved.

TEMPO-substituted polyacrylamide for an aqueous electrolyte-typed and organic-based rechargeable device

A hydrophilic radical polymer, poly（2,2,6,6-teteramethylpiperidinyloxyl-4-yl acrylamide） （PTAm）, was synthesized via oxidation of the corresponding precursor polymer, poly（2,2,6,6-teteramethylpiperidine-4-yl acrylamide）. Electrochemical properties of the PTAm layer were characterized in three aqueous electrolytes of sodium chloride （NaCl）, sodium tetrafluoroborate （NaBF4）, and sodium hexafluorophosphate （NaPF6） to optimize its activity as an organic cathode. The counter anion species significantly affected the capacity and the cycle performance of the PTAm layer. The PTAm layer in the presence of BF4？ displayed quantitative redox capacity beyond 1 μm layer thickness and maintained the discharging capacity of 110 mAh g-1 （97% vs. the calculated capacity） even after 1000 cycle charging/discharging, which could be ascribed to its appropriate affinity to the aqueous electrolyte without any dissolution into the electrolyte. A totally organic-based rechargeable cell was fabricated using PTAm and poly（N-4,4＇-bipyridinium-N-decamethylene dibromide） as the cathode and the anode, respectively, and the aqueous electrolyte of NaBF4. The cell gave a plateau voltage at 1.2 V both on charging and discharging and an excellent charging/discharging cyclability of ＆gt;2000 with high coulombic efficiency of ＆gt;95%.

Up-regulation of mitochondrial antioxidation signals in ovarian cancer cells with aggressive biologic behavior

Objective： Recently, a high frequency of mutations in mitochondrial DNA （mtDNA） has been detected in ovarian cancer. To explore the alterations of proteins in mitochondria in ovarian cancer, a pair of human ovarian carcinoma cell lines （SKOV3/SKOV3.ip1） with different metastatic potentials was examined. Methods： Cancer cells SKOV3.ipl were derived from the ascitic tumor cells of nude mice bearing a tumor of ovarian cancer cells SKOV3. SKOV3.ipl exhibited a higher degree of migration potential than its paired cell line SKOV3. The proteins in the mi- tochondria of these two cells were isolated and separated by 2-D gel electrophoresis. The differently expressed proteins were extracted and identified using matrix assisted laser desorption ionisation/time-of-flight/time-of-flight （MALDITOF/TOF）, and finally a selected protein candidate was further investigated by immunohistochemistry （IHC） method in nude mice bearing tumor tissues of these two cells. Results： A total of 35 spots with different expressions were identified between the two cells using 2D-polyacrylamide gel electrophoresis （PAGE） approach. Among them, 17 spots were detected only in either SKOV3 or SKOV3.ipl cells. Eighteen spots expressed different levels, with as much as a three-fold difference between the two cells. Twenty spots were analyzed using MALDI-TOF/TOF, and 11 of them were identified successfully; four were known to be located in mitochondria, including superoxide dismutase 2 （SOD2）, fumarate hydratase （FH）, mitochondrial ribosomal protein L38 （MRPL38）, and mRNA turnover 4 homolog （MRTO4）. An increased staining of SOD2 was observed in SKOV3.ipl over that of SKOV3 in IHC analysis. Conclusions： Our results indicate that the enhanced antioxidation and metabolic potentials of ovarian cancer cells might contribute to their aggressive and metastatic behaviors. The underlying mechanism warrants further study.