Akiyoshi Miyabayashi

Enantiomeric resolution of amino acid derivatives on molecularly imprinted polymers as monitored by potentiometric measurements

Potentiometric measurements have been applied to the detection of enantiomeric separations on molecularly imprinted polymers. A flow-through column electrode, based on the use of polymers imprinted against L-phenylalanine anilide, is described. The electrode consisted of a glass column in which the polymer was packed and where the end frits constituted the electrodes. The flow stream potential across the column can be continuously recorded as solvent is pumped through the system. The column resolved the enantiomers of phenylalanine anilide as detected by both UV absorption and potentiometric measurements and the recorded signals could be correlated with the concentration of phenylalanine anilide. The calibration graphs obtained for the UV absorption of phenylalanine anilide were linear over the concentration range investigated, whereas the potentiometric signal was shown to be exponentially linear with concentration. The application of molecular imprints to the preparation of supports suitable for chromatographic separations of enantiomers and for the preparation of specific electrodes is discussed.

Monitoring of glucose in fermentation processes using a commercial glucose analyser

SummaryA commercial glucose analyzer, originally designed for monitoring of blood glucose in patients, was tested for use in fermentation processes. The system operates in such a way that the measured value is updated every 90 seconds. The measuring range of the system is 0–5 g glucose/l and the accuracy is ±7%. The response time was found to be approximately 6 min. The system was used to follow fermentations with two different microorganisms, Saccharomyces cerevisiae and Escherichia coli in media containing up to 5 g/l of glucose. The performance was fully satisfactory and the values had a very good correlation with off-line analyses.

A potentiometric enzyme electrode for monitoring in organic solvents

A potentiometric enzyme electrode is described for monitoring reactions in organic solvents. By use of an enzyme deposited on magnetic particles which are attracted to the tip of the electrode by means of a magnetic field, it is possible to produce an electrode in which the enzyme can easily be exchanged. As an example, studies of the chymotrypsin-catalyzed ester synthesis in diisopropyl ether and in toluene at varying water contents are reported. The results are consistent with those obtained from batch experiments. Operational behaviour and signal stability of the system makes this kind of potentiometric enzyme electrode attractive for monitoring bioorganic processes.

Recording of the streaming potential over an affinity column in a continuous flow system as a means of quantifying proteins biospecifically

Abstract Measurement of the streaming potential over an affinity column is used as a means of following affinity binding of proteins to immobilized ligands. The system designed operates with one sample column and one reference column and the differential signal is a good measure of the amount of affinity-bound material. The system is used for the determination of albumin in discrete samples as well as for continuous measurements. Assays of rabbit anti-albumin antibodies are also reported; and various glycoproteins which bind to immobilized concanavalin A can be quantified. The limit of detection for proteins (down to 10−9 moles l−1) seems to be lower than that which is required for applications to process control.

A dual streaming potential device used as an affinity sensor for monitoring hybridoma cell cultivations

A dual streaming potential device was used for determining the content of monoclonal antibodies in cultivation medium for hybridoma cells. Samples of culture medium were analyzed as discrete pulses, as a continuous flow of constant concentration as well as with fluctuating concentrations. Tests were done with two subclasses of IgG as well as with IgM. Finally, the analytical device was applied to the registration of production of monoclonal antibodies in a cultivation.

An enzyme electrode based on electromagnetic entrapment of the biocatalyst bound to magnetic beads

Abstract A new type of biosensor is described. It is based on the use of a Clark-type oxygen electrode placed in an electromagnetic field. The biomolecules used in this sensor are immobilized on small magnetic beads which are added to the system when needed and removed as required. By varying the strength of the magnetic field, a homogeneous distribution of particles at the electrode tip is achieved. The electrode is used for the determination of glucose with immobilized glucose oxidase as well as cells of Saccharomyces cerevisiae .

Development of a flow-cell system with dual fuel-cell electrodes for continuous monitoring of microbial populations

Two electrode pairs in a flow-through dual fuel-cell system were used to determine the electrochemical potential generated by microbial populations. The potential difference between the counting and the reference electrode pairs was reciprocally proportional to the cell density of microorganisms in the medium, and the response time varied from 20 to 40 minutes at 30°C. Presently, the system is suitable for continuous electrochemical determination of microbial cell populations with a slow growth rate.