RSS 1.0This is the institutional Repository of the Helmholtz Centre for Infection Research in Braunschweig/Germany (HZI), the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken/Germany, the TWINCORE Zentrum für Exprerimentelle und Klinische Infektionsforschung, Hannover/Germany,Helmholtz-Institut für RNA-basierte Infektionsforschung (HIRI), Würzburg/Germany, Braunschweig Integrated Centre for Systems biology (BRICS), Centre for Structural Systems Biology (CSSB) the Study Centre Hannover, Hannover/Germany and the Centre for Individualised Infection Medicine (CiiM).
Recently Added
-
Formation of Supported Lipid / Protein Bilayers by Surface Induced Vesicle FusionFor certain applications in biosensor technology it is necessary to coat the sensor surface with a reconstituted lipid / protein membrane. Here a new technique is presented which, in contrast to the Langmuir-Blodgett- technique, allows the self assembly of supported bilayers from the aqueous phase by surface induced vesicle fusion. This paper is focussed on the formation process but gives also a detailed characterization of the physical properties of the resulting susported bilayers, as well as an analysis of the stability of these membranes for various supports.
-
A DISPOSABLE OPTICAL BIOSENSOR BASED ON TOTAL INTERNAL REFLECTION FLUORESCENCEA novel disposable biosensor device is described, based on the generation of evanescent light waves at an optical interface. The sensor is injection moulded from high optical quality plastic and consists of two parts, the waveguide and a cuvette for containing the sample solution. Antigens are attached to the waveguide surface and the reaction with antibodies is monitored by exciting and collecting fluorescent light "back-tunneled" out of the waveguide. A model assay for human IgG is used to demonstrate that this biosensor can give rapid, sensitive results.
-
OPTICAL SENSORS FOR FERMENTATION PROCESSESIn spite of the great effort of chemical engineers today the on-line measurement in fermentation processes is still limited to physical and chemical quantities. The most important biological parameters, such as biomass, substrate, product or metabolites are still not accessible to on-line measurements. As a company strongly involved in the development and production of measurement equipment for bioprocesses, Ingold Messtechnik AG started a few years ago a research program directed to the development of on-line sensors for biological parameters. For the following reasons an approach using the optical measurement technology has been considered as the most promising one: - The optical measurement technology has at least for laboratory use already reached a very high and sophisticated standard. The future developments of optical components such as semiconductor detectors or fiber optics will certainly increase the versatility of this technique. - There are many compounds of biological origin which can be directly measured by optical methods (e.g. absorption, fluorescence attenuated total reflection). - The combination of optical methods with chemical mediator substances would allow to measure also physical or chemical parameters such as pH or oxygen concentration. The use of enzymes and/or fluorescence labelled antibodies would allow to make this technique highly versatile.
-
BIOSENSORS BASED ON THE PYROELECTRIC BEHAVIOUR OF BIOLOGICAL SYSTEMSLiving organisms contain pyroelectric structures which function extremely well as pyroelectric detectors and transducers. Organisms are thus able to detect and discriminate between different stimuli in the environment, such as rapid changes of temperature, of illumination, of uniaxial and hydrostatic pressure. The different stimuli represent different forms of energy and are transduced into the nearly uniform type of electrical signals, whose voltage/time-course frequently depends on dX/dt (X, stimulus; t, time). The voltage/timecourses of the pyroelectric responses of biological systems (like nerve tissue) on the one hand, and of nonbiological pyroelectric crystals (like tourmaline) or nonbiological pyroelectric polymers (like polyvinylidene fluoride) on the other hand, to external stimuli are analogous.
-
FIBER OPTICAL pH-SENSOR BASED ON LASER-INDUCED FLUORESCENCEA fiber optical pH-sensor based on laser-induced fluorescence was developed. The fluorescence was ww. with the light of a Helium-Neon-Laser (5°mW, Polytec model PL 7504) emitting at X4 632.8 nm. The dye used was tetra-(p-sulfophenyl)-porphyrine (Ventron), ‘whieh-has in an aqueous solution an extinction coefficient at A = 632.8 nm of e = 4365 I/mol - cm. Its fluorescence behaviour changes at different-pH-values- (figure). It is a water-soluble dye and the sulfo-groups give the possibility to immobilize this dye on anion exchange resins. The fluorescence spectrum of this dye has a maximum at pH = 6.8 at A= 675 nm and A= 700 nm, respectively, which offers the advantage of a ratio-measurement.
