Covalent immobilization of Pseudomonas cepacia lipase on semiconducting materials

Lipase from Pseudomonas cepacia was covalently immobilized on crystalline silicon, porous silicon and silicon nitride surfaces. The various stages of immobilization were characterized using FTIR (Fourier transform infrared) spectroscopy. The surface topography of the enzyme immobilized surfaces was investigated using scanning electron microscopy (SEM). The quantity of the immobilized active enzyme was estimated by the para-nitrophenyl palmitate (pNPP) assay. The immobilized lipase was used for triglyceride hydrolysis and the acid produced was detected by a pH sensitive silicon nitride surface as a shift in the C-V (capacitance-voltage) characteristics of an electrolyte-insulator-semiconductor capacitor (EISCAP) thus validating the immobilization method for use as a biosensor.     

Immobilization of lipase from Candida rugosa on layered double hydroxides for esterification reaction

Synthesis of layered double hydroxides (LDHs) of Zn/Al-NO3- hydrotalcite (HIZAN) and Zn/Al-diocytyl sodium sulfosuccinate (DSS) nanocomposite (NAZAD) with a molar ratio of Zn/Al of 4:1 were carried out by coprecipitation through continuous agitation. Their structures were determined using X-ray diffractometer spectra, which showed that basal spacing for LDH synthesized by both methods was about 8.89 A. An expansion of layered structure of about 27.9 A was observed to accommodate the surfactant anion between the interlayer. This phenomenon showed that the intercalation process took place between the LDH interlayer. Lipase from Candida rugosa was immobilized onto these materials by physical adsorption method. It was found that the protein loading onto NAZAD is higher than HIZAN. The activity of immobilized lipase was investigated through esterification of oleic acid and 1-butanol in hexane. The effects of pore size, surface area, reaction temperature, thermostability of the immobilized lipases, storage stability in organic solvent, and leaching studies were investigated. Stability was found to be the highest in the nanocomposite NAZAD.     

Capillary columns with immobilized stationary phases. Part 4: A moderately polar phase,OV-1701

Whereas the immobilization of apolar silicone phases is essentially understood and mastered, the corresponding treatment of even moderately polar phases remains problematical. Upon attack by peroxide radicals, these phases respond by forming active transformation products rather than by bonding to the support surface or to neighboring molecules. OV-1701 is at present the most polar stationary phase which can reasonably be immobilized. An essential feature of the practical procedure is the prevention of film breakage after coating the inert support surface and before immobilization. Two ways of overcoming this problem are presented.     

Green synthesis of chitosan-stabilized silver-colloidal nanoparticles immobilized on white-silica-gel beads and the antibacterial activities in a simulated-air-filter

This study explored the green synthesis and immobilization of colloidal silver nanoparticles (AgNPs) on a solid compatible support. Its antibacterial properties in reusable air filters are also discussed. The chitosan stabilized colloidal AgNPs (chi-AgNPs) were prepared using visible light irradiation in methanol. The UV–Vis, FTIR spectra, and TEM confirmed the chi-AgNPs formation. The immobilization technique of chi-AgNPs on the surface of white-silica-gel beads, which was previously coated chitosan (chi-SiG), was effective. The immobilized silver particles (AgNPs-[chi-SiG]) were solid, stable, dispersed, and nano-size. Both AgNPs-[chi-SiG] and chi-SiG exhibited antibacterial properties and prevented the growth of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria in agar media. Air filter containing the AgNPs-[chi-SiG] showed high antibacterial activity against Bacillus subtilis in the air.     

氨功能化介孔MCM-41固载锰卟啉作为萘羟基化多相催化剂

将不同含量的四(五氟苯基)卟啉锰固载于表面氨基功能化的MCM-41介孔分子筛,所得样品通过粉末X射线衍射、氮气吸附脱附、傅里叶变换红外光谱、X射线光电子能谱、扫描电子显微镜、漫反射紫外-可见光谱、热重和差示扫描量热、电感耦合等离子体进行了表征.结果表明,四(五氟苯基)卟啉锰通过Mn与氨基的轴向配位固载于MCM-41.所制备的样品作为多相催化剂在以间氯过氧苯甲酸为氧化剂选择氧化萘反应中表现出良好的催化性能,且多次使用后没有明显的活性损失.     

Immobilization of uricase within polystyrene using polymaleimidostyrene as a stabilizer and its application to uric acid sensor

A novel amperometric uric acid (UA) sensor has been developed by coating the surface of a gold electrode with a polystyrene (PS) membrane formed by 30 μL of a 30 mg mL⁻¹ PS chloroform solution combined with 30 μL of a 5 mg mL⁻¹ polymaleimidostyrene (PMS) solution as a dispersant for enzyme, uricase; this membrane has been successfully employed as an immobilization support for uricase. In the PS membrane, PMS forms micelle-like structures containing uricase in an active state. This immobilized uricase membrane permits the permeation of oxygen, which is consumed by the uricase reaction. A good linear relationship is obtained over the concentration range of 5-105 μM. The concentration of uric acid was determined at a negative potential based on the decrease in the reduction current of oxygen and the interference of l-ascorbic acid can be completely eliminated.     

Immobilization stress increases endogenous monoamine oxidase (MAO) inhibitor in rat liver

Although the physiological role of endogenous monoamine oxidase (MAO) inhibitor still remains unclear, the present study examined whether or not immobilization stress (IMMO) induce MAO inhibitor. An endogenous inhibitor of MAO was separated by gel filtration from 105,000 g supernate in rat liver cytosol following IMMO. The molecular weight of this inhibitor was estimated to be 500-600 by gel filtration. This inhibitor was proved to be heat-stable resistant to protease treatment. IMMO for 2 h significantly decreased MAO. These results suggest that this inhibitor is induced by IMMO. MAO activity in rat liver might be regulated by the level of this inhibitor.     

Immobilization of Urease from Pigeonpea (<Emphasis Type="Italic">Cajanus cajan</Emphasis>) on Agar Tablets and Its Application in Urea Assay

The pigeonpea urease was immobilized on agar, a common gelling substance. The tablet strips were used as moulds to cast agar tablets of uniform shape and size. The time and temperature of solidification of agar was 6 min and 44 degrees C, respectively. The 5 % agar (w/v) and 0.019 mg protein/agar tablet yielded an optimum immobilization of 51.7%. The optimum pH was shifted through 0.2 U (from 7.3 to 7.5) towards basic side upon immobilization. The optimum temperature of soluble and immobilized urease was 30 degrees C and 60 degrees C, respectively, showing the improvement in thermal stability of urease. There was an increase in K m from 3.23 to 5.07 mM after immobilization. The half-lives of soluble and immobilized urease were 21 and 53 days, respectively, at pH 7.3 and 4 degrees C. The urea was estimated in different blood samples with the help of immobilized urease and the results were consistent with those from clinical pathology laboratory through an autoanalyzer (Zydus Co., Rome, Italy).