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INTEGRATED DIFFERENCE ENFETs
No full textEnzyme field effect transistors (ENFETS) were assembled by
immobilizing enzymes to a multigate proton and fluoride ion
sensitive field effect transistor. Two variations of difference
mode measurements of glucose have been realized. All the gates
and electrodes at the chip have been homogeneously covererd by a
crosslinked, enzyme containing Polyurethane matrix. The
difference of the output voltages of a PH-ENFET and a pF
reference FET (REFET) or the difference of a pF-ENFET and a pHREFET
are measured using an integrated thin film noble metal
electrode as pseudo-reference
BIOSENSOR SYSTEMS BASED UPON RECEPTOR FUNCTIONS
No full textWediscuss prototype structures and basic principles of electrical and optical detection and
characterize our spectroscopies to control interfaces of sensors on the atomic scale. We
then present two receptor principles which will utilize these structures and spectroscopies
in a joint researcheffort. Thefirst principle concerns immunosensors based upon synthetic
antigens linked to lipopeptides and voltage-dependent k- helices. The second principle
concerns transport protein biosensors based upon lactose permease
Thin and Thick Film Chemical Sensors
No full textChemical sensors with solid ion-conductors or mixed ion- and electron-conductors have
been prepared by the thin film ICB (lon Cluster Beam Evaporation) and by the thick film
screen printing methods. By the ICB method, the sensor material TiO, was deposited on
sapphire and quartz substrates. The deposited film of about 1 um thickness has
oriented texture. By the screen printing method, solid ion-conductors Nasicon
(Nay.xZroSi,P3-,Oj2) and YSZ (yttria stabilized zirconia) have been deposited onto
a-alumina substrate. An all-thick film hydrogen sensor based on Nasicon containing
sodium tungsten bronze (Na,WO.) reference electrode and porous platinum working
electrode was produced by the screen printing method. The range of this sensorlies
between 100 ppm and 100% hydrogen in air
FIA - A NOVEL TOOL FOR BIOTECHNOLOGY AND SENSOR DEVELOPMENT
No full textFlow injection analysis is explained and showed as a tool for novel sensor
concepts, development and testing
THE FLEXIRUBIN-TYPE PIGMENTS, CHEMOSYSTEMATICALLY USEFUL COMPOUNDS
No full textThe flexirubin-type pigments are compounds of a novel chemical structure: A polyenoic
acid chromophore with a para-hydroxy phenyl ring (ring A) in the end position
is esterified with a di-alkylated resorcinol (ring B). The basic structure may be modified
by a) a variation of the chain length of the chromophore between 6 and 8 conjugated
double bonds; b) a methylation in the meta-position in ring A; c) a chlorination
in the meta-position in ring A; and d) broad variations of the hydrocarbon
chains in ring B with respect to the chain length and linearity. All strains, which
contain flexirubin-type pigments, also produce chlorinated counterparts of most of
the structural variants. The distribution of flexirubin-type pigments among yellow
bacteria makes them very useful chemosystematic markers. They are found in most
strains of Flexibacter and Cytophaga-like bacteria isolated from soil and freshwater,
in Sporocytophaga, and in many flavobacteria of the low GC-group. They seem to be absent
in gram-positive bacteria, in flagellated bacteria, and in most Cytophaga-like
bacteria isolated from marine environments. Many bacteria, which produce flexirubintype
pigments, contain complex mixtures of up to 25 different structural variants,
but nevertheless it seems that each taxonomic group synthesizes its own specific modification
of the pigment. In contrast to carotenoids, also present in many of the
above-mentioned organisms, flexirubin-type pigments are located in the outer membrane
of the gram-negative cell wall. The biological function of the new pigments is still
obscure: Unpigmented mutants can be obtained, and grow well under laboratory conditions
OCCURENCE OF FLAVOBACTERIUM MENINGOSEPTICUM. SEROTYPES IN FRANCE
No full textEighty-five clinical strains of Flavobacterium meningosepticum, mostly
isolated in France, were assigned to 12 serotypes (number of strains) : A m»,
B (1), 0. (5), ERBE ESEL), BUND, 7.66), a 2), L CD), m IL), (2);
rough strains (5)
RAPID SOLID-PHASE PHOSPHOTRIESTER SYNTHESIS OF DNA FRAGMENTS ON CONTROLLED PORE GLASS AND APPLICATION TO THE PREPARATION OF A GENE FOR SOMATOMEDIN C
No full textA solid-phase method for micro-scale synthesis of oligodeoxyribonucleotides
is described. The method involves use of controlled pore glass as support and
phosphotriester chemistry for chain assembly. The 9-phenylxanthen-9-yl (pixyl)
group was used for 5' hydroxyl protection and the phthaloyl group was used for protection
of the ne position of deoxyadenosine residues. A new, more alkali-stable
linkage between oligonucleotide and support was used, based on the sequential reac-—
tion of tolylene-2,6-diisocyanate with a protected nucleoside and then support.
Using the improved chemical methods all 23 oligonucleotides required for assembly
of a gene for Somatomedin C (insulin-like growth factor I) were synthesised. The
oligonucleotides were 5' phosphorylated and ligated in one step to form the complete
DNA duplex of 230 base pairs. The duplex was cloned into a bacteriophage M13 vector
and clones sequenced by the 'dideoxy' method
TOTAL SYNTHESIS OF YEAST ALANYL trNa
No full textBy means of a combination of chemical and enzymatic methods, we have synthesized an
RNA molecule which has the same chemical composition (i.e. it contains all the
common as well as the modified nucleotides) and structure as the natural yeast
alanyl tRNA, elucidated by R.W. Holley et.al. and modified by others, and which is
biologically active (1). In the presence of rat liver aminoacyl-tRNA synthetase, the
synthetic tRNA can be charged with alanine and the incorporation of alanine from the
charged tRNA molecule into proteins is readily demonstrated in a rabbit reticulocyte
‘ lysate system
MIKROFILTRATION VON FERMENTERBRÜHEN
No full textIn der Biotechnologie stellt die Crossflow-Mikrofiltration
ein modernes Verfahren zur Aufarbeitung von Fermenterbrühen
dar. Bei intrazellulären Inhaltsstoffen können die
Zellen mit Hilfe dieser Technik vor ihrem Aufschluß angereichert
werden /1/. Im Falle von extrazellulären
Wertstoffen ist es möglich, diese durch die Mikrofiltrationsmembran
von den Zellen sowie von den aus dem
Nährmedium stammenden Feststoffen abzutrennen. Die
Vorgehensweise beider Isolierung gelöster Wertstoffe
mittels der Crossflow-Mikrofiltration wird am Beispiel
der alkalischen Protease beschrieben, wobei insbesondere
die Abhängigkeiten des Permeatflusses und der Retention
vom Membranmaterial, von der mittleren Porengröße
der Membran, von den Betriebsbedingungen,
den physikalischen Daten der Fermenterbrühe und vom
Feststoffzusatz diskutiert und quantifiziert werden
Anwendung von Membranen bei der Aufarbeitung von Interferon-ß
No full textUltrafiltrationen von Interferon-ß ergeben im Unterschied zu solchen von
Interferon-a unreproduzierbare und teils sehr hohe Aktivitätsverluste. Die
Versuchsergebnisse zeigen, daß diese Verluste zum Teil auf einer Adsorption des
Proteins an Membranen beruhen. Diafiltrationen mit einer gleichzeitigen Anderung
des pH-Wertes führen zu weiteren hohen, proteinspezifischen Verlusten‘
Solche Verluste können jedoch wegen der hohen Produktionskosten für Interferon-
8 nicht akzeptiert werden und daher kommen Membranprozesse bei der Herstellung
pharmazeutischer Präparate von Interferon-ß aus tierischen Zellkulturen nur
bedingt in Frage.
Da Interferon-8 von einigen Kunststoffen stark, von anderen aber wiederum
nicht absorbiert wird, sind neue Membranpolymere von Interesse