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Biosensors Based on Chemically Modified Electrodes with Dehydrogenases as Biological Components
No full textGraphite electrodes were modified by adsorption of phenazine methosulphate
(PMSt) or N-methyl phenazinium tetracyanoquinodimethane
(NMP*TCNQ-) as mediators for NADH-oxidation. Different dehydrogenases
were entrapped in a dialysis membrane together with molecular weight
enlarged NAD (NAD-PEG). These electrodes could be used for the
detection of substrates of dehydrogenases at potentials around 0 mV
versus a Ag/AgCl-electrode
Title - Preface - Foreword - Contents - List of authors
No full textIn the two years which have elapsed since the First International Workshop on Biosensors was
held at the GBF in 1987 (1), the attractiveness of the field has further increased. Major reasons
might be found in the growing numberof biosensors now under commercialisation, in the
permanent stimulation through novel sensor design and bio-technology, and last not least, in
several attractive governmental programs.
The Federal Ministry of Research of Technology (BMFT) in Bonn, W.-Germany, is presently
supporting biosensor R&D with a funding of 15 Mill. DM over the period of 1988 to 1991. Earlier
BMFT programs were directed towards sensors in medicine and machinery ("microperiphery").
Against this background, a national status seminar on the state of this technique was
clearly desirable, and the GBF as the National W.-German ResearchInstitute for Biotechnology
(which funds a large in-house biosensor research unit) was entrusted with the organisation. As
a format, an international workshop comprising the four countries of German language was
chosen; at the same time, it was decided that the proceedings would be published in English
language in order to benefit international cooperationin this field.
As a result, about 100 scientists from the FRG, the GDR, Austria and Switzerland gathered in a
warm and sunny Braunschweig on May 22 and 23, 1989. The statistics of this meeting summarized
in Table 1.
In spite of the limited time available, all posters were briefly explained during thefirst plenary
session, and all participants from industry agreed to outline the particular interest of their
company in biosensor R&D. Both features are believed to have greatly stimulated communication
during the workshop.
While the limitation to participants of German language obviously set limits to the overall format,
it was felt helpful by industrial, academic and governmental participants to get a better
perspective of this area of research in Central Europe. In appreciation of the many excellent
contributions which are summarized in this monograph,it can be maintained that biosensor R&D
in the FRG, the GDR, Austria and Switzerland is very active and of high quality. It is beyond
doubt that in the years to come some of the equipment presented during this workshop will
find its way to the marketplace. In addition, some of the novel concepts described at this
workshopare hopedto stimulate international research.
In 1991 the progress in this field will be discussed on a Biosensor workshop organized in the
GDRonthe basis of a contract between BMFT and the Ministry of Science and Technology of
GDR.
The editors of this Proceedings would like to extend their thanks and appreciation to all speakers
and exhibitors of posters, and to many colleagues at the GBF who helped so much in
organizing the event*
Bioreaktoren : ein Leitfaden für Anwender
No full textKernstiick der meisten biotechnologischen Verfahren ist der Bioreaktor,
d.h. ein Apparat, in dem die gewiinschte biologische Reaktion unter monoseptischen
Bedingungen abläuft. Von daher ist es verständlich, daß für
viele "Einsteiger" in die Biotechnologie zunächst der Reaktor im Blickpunkt
steht. Als Einsteiger sind hier sowohl potentielle Hersteller als auch
Nutzer von Bioreaktoren zu verstehen, d. h. sowohl Apparate- und Anlagenbauer,
die zukünftig als Lieferanten am Bioreaktormarkt auftreten wollen,
als auch Firmen aus verschiedenen Bereichen, die biotechnologische Produkte
herzustellen beabsichtigen.
Aufgrund der hohen Popularität der Biotechnologie und der großen Erwartungen,
die an ihre Entwicklung geknüpft werden, hat die GBF als Großforschungseinrichtung
der Bundesrepublik Deutschland und damit als Anlaufstelle
für viele Einsteiger neben der Abwicklung ihres F+E-Programms viel
Beratung und Aufklärung geleistet. Im Sinne einer Vereinfachung und Rationalisierung
erschien es uns daher sinnvoll und notwendig, einige praktische
Aspekte der Konstruktion und des Betriebs von Bioreaktoren sowie
seiner MSR-Ausstattung in diesem Heft zusammenzufassen. Diese Ausführungen
sind auch Bestandteil verschiedener Kurse, die an der GBF durchgeführt
werden und in die praktische Biotechnologie einführen.
Die Zahl der in der einschlägigen Literatur vorgeschlagenen Bioreaktoren
ist groß, ihre Einsatzmöglichkeiten unter praktischen Bedingungen sind
jedoch meist ungeklärt. Abgesehen von einigen Spezialfällen - wie z.B. dem
Einsatz von Blasensäulen in der Zellkulturtechnik oder zur Herstellung von
SCP - stellt der gerührte Kessel den Standard-Bioreaktor dar. Daran wird
sich auch in Zukunft so schnell nichts ändern. Die Ausführungen in diesem
Band beziehen sich daher ausdrücklich auf den Rührkesselreaktor.
Im Biotechnikum der GBF ist eine Erneuerung bzw. Modernisierung des Fermenterparks
notwendig geworden. Eine Reihe von Beschaffungsmaßnahmen wird derzeit
abgewickelt. Als Teil III dieses Hefts wird der dabei verwendete Ausschreibungstext
für die Angebotserstellung abgedruckt. Dieser enthält
sicherlich einige GBF-spezifische Details, faßt andererseits aber alle
wichtigen Punkte zusammen, die bei der Beschaffung von Bioreaktoren zu
beachten sind
EMENDATION OF THE GENUS FLAVOBACTERIUM AND THE STATUS OF THE GENUS. DEVELOPMENTS AFTER THE 8TH EDITION OF BERGEY'S MANUAL
No full textIn the 8th edition of Bergey's Manual [25] the genus Flavobacterium remained
taxonomically heterogeneous, being divided into two sections. Section I contained
six non-motile species with the G+C content of their DNA in the range 30 to 42 mol %
(low G+C content strains) and Section II contained six species that were either nonmotile
or motile and peritrichous but with G+C contents in the range 63 to 70 mol %
(high G+C content strains). Here we describe the general background and sequence of
events, culminating in an emended description of the genus [12], in which restriction
of Flavobacterium to certain well-described low G+C content species is proposed.
The reasons for replacing the current type species F. aquatile, with F. breve will
also be discussed. Although only four species conform to the emended description of
Flavobacterium at present, other taxa that are candidates for inclusion in the genus
will be described as well as the taxonomic problems associated with them; particular
reference will be made to Flavobacterium Group IIb [23]. The taxonomic status of the
high G+C content strains of Section II will be discussed as will the status of
certain taxa, such as Group IIf [23], which are sometimes referred to as
Flavobacterium-like
BIOSENSORS: CHALLENGES FOR THE 1990'S
No full textThe needs of biotechnology and biomedicine require improved measurement devices for
purposes of analysis, monitoring and control, with specific applications in fermentation,
antibody production, drug testing, and patient monitoring. Electrochemical
biosensors provide a possible means of meeting such needs provided the capabilities
of such sensors can be extended to a wider range of biomolecules and more complex
matrices. Several recent initiatives suggest that some new approaches to the development
of potentiometric and amperometric biosensors may be effective for this purpose.
Such initiatives for the development of novel biosensors require a synthesis
of biological and analytical concepts. Possible strategies involve the use of
chemoreceptor structures, immunoagents, and cellular materials from plant or animal
sources
ENZYME ELECTRODES: FROM THE SELF-CONTAINED PROBE TO THE DESIGN OF AN AUTOMATIC ANALYZER
No full textAnalytical potentialities of collagen films used in our group for enzyme immobilization werefirst
tested for the design of a self-contained glucose electrode based on hydrogen peroxidedetection . For
this purpose, an enzymic disc of the appropriate size was cutout of the bioactive membrane and
tightly pressed against a platinum anode with a screwed cap . This biosensor wascharacterized by a
very low detection limit , 10-8 M, a wide linear calibration range ‚107 to 2.103 M, and the possibility
to perform several thousands of assays with the samedisc.
One of the main bottlenecks for practical applications of enzyme electrodes in industry is the
detection and subtraction of interferences. A differential two-electrode system has been set up and a
microprocessor-based analyzer "Glucoprocesseur"® derived from the above mentioned work was
designed and marketed by Solea-Tacussel, France. Results are displayed 30 seconds after injections
which can be performed at 90-secondintervals using unpretreated samples. injection is manual but
filling and emptying the measurementcell are automatic, Excellent results were obtained in foodstuffs
with this analyzer.
We proposed recently a very simple andfast procedure to prepare cheaply andreliably new
enzymic membranes by using a commercially available preactivated membrane : the Pall Biodyne™
ImmunoAffinity membrane for biotechnological applications. Enzyme immobilization occurs
spontaneously in a few minutes. Depending on the oxidase used , different analytes could be
monitored with the analyzer equipped with such membranes . Anyone who needsto prepare his own
enzymic membrane with non-commercially available enzymes maydo soeasily and in ouropinion, this
may make such biosensors more widely used in industrial processes
POSSIBILITIES FOR BIOSENSORS BASED ON NEURORECEPTORS
No full textThe incorporation of a protein that selectively binds the compound to be
measured is one of the most efficient methods for imparting selectivity into the
design of biosensors. Enzymes and immunoproteins, such as antibodies, have been
widely studied so far. Neuroreceptors constitute another class of proteins which
very selectively bind certain compounds and which in principle can be used to
develop biosensors for the detection of specific drugs, potent toxins, or other
compounds. Since neuroreceptors in their natural environment are found in cell
membranes, the first major task is to separate the receptor protein from the cell,
while retaining binding specificity, in large enough quantities to enable reconstitution,
immobilization, and biosensor readout studies to be carried out. The
acetylcholine receptor and the gamma-amino butyric acid (GABA) receptor are being
intensely studied at present
RESULTS OF A DISCUSSION ABOUT TECHNICAL PROBLEMS IN TAXONOMIC RESEARCH ON FLAVOBACTERIA AND CYTOPHAGA-LIKE BACTERIA
No full textThe participants of the symposium felt, that an exchange of results and ideas between
the two groups of investigators working with flavobacteria on the one side,
and with Cytophaga-like bacteria on the other, could potentially be very useful and
stimulating for both sides, particularly as the borders between some of these bacteria
tend to vanish. Closer contacts within each group of microbiologists, and between
the two,would be highly desirable.
To promote such contacts it was proposed, a) to start a Newsletter on Flavobacteria
and Cytophaga-Like Bacteria, and b) to repeat meetings of the kind just concluded
from time to time. Dr. 0.B. Weeks from Las Cruces, New Mexico, kindly took
over responsibility for compiling and distributing the Newslette
REGIO- AND STEREOSPECIFIC SYNTHESIS OF 7-DEAZAPURINE 2'-DEOXYRIBONUCLEOSIDES AND INCORPORATION OF NUCLEOSIDE ISOSTERES INTO OLIGONUCLEOTIDES
No full text2'-Deoxytubercidin and 7-deaza-2'-deoxyguanosine, isosteres of the
parent nucleosides 2'-deoxyadenosine and 2'-deoxyguanosine have been
synthesized via phase-transfer glycosylation of appropriately protected
pyrrolo[2,3-d]pyrimidines with 1-chloro-2-deoxy-3 ,5-di-O-p-toluoy1-Derythro-
pentofuranose via a regio- and stereospecific route. The nuclecside
isosteres were provided with suitable protecting groups and converted
into their O-3'-phosphoramidites. Application of these compounds
in solid-support oligonucleotide synthesis yielded self-complementary
oligomers with alternating d(TuT) or d(c’Gc) sequences. Additionally
the incorporation of the 7-deazapurine 2'-deoxyribofuranosides into the
Eco RI sequence was accomplished. Applying phosphite triester condensation
in solution, (2',5')- and (3',5')-tubercidylyl-tubercidins were
synthesized