Nowadays, microreactors are finding more and more applications in different fields of chemical and pharmaceutical industry, biotechnology and medicine. The application of different microreactor systems in intensification of the biochemical production processes is widely studied. Some researches claim that 50 % of reactions in the fine chemical or pharmaceutical industry could benefit from a continuous process based mainly on microreactor technology, and for the majority (44 %) a microreactor would be the preferred reaction device.
Decreased channel dimensions of microreactors (on the order of 10 – 500 µm) afford numerous advantages that lead to increased reaction efficiency. A high surface to volume ratio, faster diffusion dominated transport, enhanced heat transfer and thus reduced energy demands, good process control, high throughput, usage of minimal (microliters) of reagent volumes, etc., are some of a microreactor advantages that are usually stressed. Microreactors could be easily coupled with numerous detection techniques together with the pretreatment of the samples on the one single unit. Having in mind all those benefits one of the main motivations for the use of microreactor technology is the gain in the yield and safety.
Although a great majority of the reaction systems that are studied in microreactors are connected with chemical synthesis, biocatalysis and biotransformations in a microreactor are demonstrated as promising alternative. Syntheses, oxidations, transesterifications, polymerizations, hydrolyses and coenzyme regenerations catalysed by enzymes or whole cells are just some of numerous different biotransformations that have been successfully performed in microreactors.
Microreactor advantages in biotransformations will be demonstrated on three case studies, namely, (i) alcohol dehydrogenase catalyzed hexanal production with in situ NAD+ cofactor regeneration and product separation, (ii) two-phase aqueous extraction of polyphenols and, (iii) biocatalytic production of biodiesel using an enzyme lipase with integrated biodiesel purification.