摘要：

The coenzyme NAD+ (nicotinamide adenine dinucleotide) is commonly used in biocatalytic oxidations catalysed by the enzyme alcohol dehydrogenase (ADH). As the price of the coenzyme NAD+ is extremely high, it is essential to regenerate the reduced form of the coenzyme back into the oxidized form. In this work NADH oxidation was carried out in a microreactor by reversible oxidation of ethanol to acetaldehyde with the enzyme alcohol dehydrogenase (ADH). Different forms of biocatalyst were studied (suspended and immobilized ADH (1) and permeabilized baker's yeast cells as the source of ADH (2)). The best results were obtained by using suspended enzyme in a microreactor where 100% conversion of NADH was achieved (τ = 0.8 s). Additionally, a new concept of coenzyme regeneration which combines the advantages of microreactor technology with the advantages of magnetic nanoparticles (MNPs) application was developed (3). Two different microreactor systems with MNPs were studied, one with stationary MNPs trapped on the inner surface of microchannel by permanent magnetic field and one where the MNPs actively move across the channel (movement inside microchannel allowed by oscillating magnetic field). The system operated continuously for 7 days.

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