2-modified 1,3-diacylglycerols as new surfactants for the formation of reverse micelles

New 2-modified 1,3-diacylglycerols such as 1,3-dilauroylglycerol 2-disodiumphosphate and analogues were characterized with respect to their tendency to form reverse micelles in isooctane and isooctane/1-hexanol. The water content of the reverse micelles was determined by Karl-Fischer titration. The critical micelle concentration of the compounds was estimated by fluorescence measurements using rhodamine B as indicator. The concentration regions where reverse micelles are observed were characterized by pseudoternary phase diagrams. The ability of the surfactants to extract proteins into organic phase was examined for cytochrome c. The properties of the compounds were compared with the behaviour of the corresponding regioisomeric 3-modified 1,2-diacylglycerols as well as lecithin and the surfactant AOT, which is preferably used for the formation of reverse micelles. The results suggest that the position of the head group in the modified diacylglycerols is of low importance for the phase behaviour, whereas the ability to form reverse micelles decisively depends on the structure of the head group. (orig.)SIGLEAvailable from TIB Hannover: F96B453+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Amperometric AlgalChlorella vulgaris Cell Biosensors Based on Alginate and Polypyrrole-Alginate Gels

International audienc

Optimization of the basal medium for improving production and secretion of taxanes from suspension cell culture of <it>Taxus baccata</it> L

<p>Abstract</p> <p>Background and purpose of the study</p> <p>Taxol is one of the most effective anticancer drugs that isolated from <it>Taxus</it> sp. due to the slow growth of <it>Taxus</it> trees and low concentration of Taxol in the tissues, the biotechnological approaches especially plant cell culture have been considered to produce Taxol in commercial scale.</p> <p>Methods</p> <p>We investigated the effects of basal medium type used in culture media on production of Taxol and other taxane compounds from cell suspension culture of <it>T. baccata</it> L. Briefly, five commonly basal media including Gamborg, Murashige and Skoog, Woody Plant, Schenk and Hildebrandt, and Driver and Kuniyuki medium were used for preparing separate suspension culture media. The intra- and extra-cellular yields of taxanes were analyzed by using HPLC after 21 days period of culturing.</p> <p>Results</p> <p>The yields of taxanes were significantly different for the cultures prepared by different basal media. Moreover, the effects of basal medium on the yield of products differed for varius taxane compounds. Maximum yields of Baccatin III (10.03 mgl^-1) and 10-deacetyl baccatin III (4.2 mgl^-1) were achieved from the DKW basal media, but the yield of Taxol was maximum (16.58 mgl^-1) in the WPM basal media. Furthermore, the secretion of taxanes from the cells into medium was also considerably affected by the type of basal medium. The maximum extra-cellular yield of Taxol (7.81 mgl^-1), Baccatin III (5.0 mgl^-1), and 10-deacetyl baccatin III (1.45 mgl^-1) were also obtained by using DKW basal medium that were significantly higher than those obtained from other culture media.</p

Performance of a Cyanobacteria Whole Cell-Based Fluorescence Biosensor for Heavy Metal and Pesticide Detection

Whole cell biosensors always face the challenge of low stability of biological components and short storage life. This paper reports the effects of poly(2-hydroxyethyl methacrylate) (pHEMA) immobilization on a whole cell fluorescence biosensor for the detection of heavy metals (Cu, Pb, Cd), and pesticides (dichlorophenoxyacetic acid (2,4-D), and chlorpyrifos). The biosensor was produced by entrapping the cyanobacterium Anabaena torulosa on a cellulose membrane, followed by applying a layer of pHEMA, and attaching it to a well. The well was then fixed to an optical probe which was connected to a fluorescence spectrophotometer and an electronic reader. The optimization of the biosensor using several factors such as amount of HEMA and drying temperature were undertaken. The detection limits of biosensor without pHEMA for Cu, Cd, Pb, 2,4-D and chlorpyrifos were 1.195, 0.027, 0.0100, 0.025 and 0.025 µg/L respectively. The presence of pHEMA increased the limits of detection to 1.410, 0.250, 0.500, 0.235 and 0.117 µg/L respectively. pHEMA is known to enhance the reproducibility of the biosensor with average relative standard deviation (RSD) of ±1.76% for all the pollutants tested, 48% better than the biosensor without pHEMA (RSD = ±3.73%). In storability test with Cu 5 µg/L, the biosensor with pHEMA performed 11.5% better than the test without pHEMA on day-10 and 5.2% better on day-25. pHEMA is therefore a good candidate to be used in whole cell biosensors as it increases reproducibility and enhances biosensor storability