engleski

Microreactors - think big by going small

In the last two decades, microreactor technology has seen exponential growth. This new concept in production, analysis and research is finding increasing application in many fields. Benefits of this new technology posed a vital influence on chemical industry, biotechnology, pharmaceutical industry, medicine, life science, clinical and environmental diagnostic (Šalić et al., 2012a). Microreactors offer many fundamental advantages in comparison with classical macroreactors that were achieved by shrinking the characteristic dimensions of macroreactor on the microscale. Typical dimensions of microchannel, basic microreactor structure, are in the range from 10 µm to 500 µm (Yoshida et al., 2005). Large surface to volume ratio, excellent mass and heath transfer, short residence times, smaller amount of reagents, catalyst and waste products comparing to macroscale, laminar flow, effective mixing and better process control and small energy consumption are just some of the advantages (Ehrfeld et al., 2000). Higher selectivity and more precise kinetic information can be obtained (Chovan and Guttman, 2002) performing reactions in microcsale. General opinion is that, biotechnology, pharmaceutical and fine chemical industry could benefit from this technology approach, especially in case when it is important to develop new techniques that enable the rapid synthesis and screening of novel chemical entities with low investment costs. Roberge et al., 2005 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 %) microreactors would be the preferred reaction device. Although a great majority of the reaction systems that are, at the moment, studied in microreactors are connected with chemical synthesis, biocatalysis in microreactor was shown to be a promising alternative (Thomsen and Nidetzky, 2009). Syntheses (Schwartz et al., 2009, Mugo and Ayton, 2010), oxidations (Tišma et al., 2009, Wiles et al., 2009, Šalić et al., 2011) transesterifications (Žnidaršič-Plazl and Plazl, 2009, Machsun et al., 2010), polymerizations (Kundu et al., 2011), hydrolyse (Čech et al., 2012), coenzyme regeneration (Šalić et al., 2012b) etc. are just some of numerous different reactions that have been successfully performed in microreactors. Results that were obtained by using microreactor technology were significantly better in comparison to macroreactor technologies. Additionally, in order to make microreactor technologies even more sustainable, the use of enzymes within the whole cells, in suspended or especially immobilized form, is also gained considerable attention (Stojkovič and Žnidaršič-Plazl, 2012). Lower costs, due to the fact that catalyst extraction and purification is avoided, an opportunity to recycle the enzyme-containing cells is provided and the biotransforming enzyme may be stabilised in the intra-cellular environment, are some advantages over isolated enzymes (Nikolova and Ward, 1992). Connecting microreactors to operate in parallel or in series (numbering – up) compact microplants could be build-up (Carpentier, 2005 ; Löwe et al, 2002). One of the biggest advantages of these operation systems is that continuous operation is uninterrupted if one of the units fails, because it could easily be replaced with no effect on the other operating units. In last few years, integrated micro-systems, so called micro-total-analysis-systems (µ-TAS) or lab-on-chip (LOC) are becoming more and more interesting. Optimally, such devices would automatically perform sampling, sample preparation, separation, detection and data processing in a fully integrated manner. In addition these devices offer potential as remote controlled systems, which could be placed in inaccessible locations for continuous monitoring of biotechnology processes (Tanaka et al., 2006 ; Fletcher et al., 2002). Performing biochemical reactions within microfluidic systems also provides the opportunities to perform real time separation (Watts and Haswell, 2003). Microchip technology is being more and more used for analysis of cellular biochemical systems because the scale of microdevice fits to a size of the cell. Using this technology it is possible to get information about behavior of single cell which is not possible during study in large scale (Le Gac and van der Berg, 2009). In this manuscript intensive overview of the recent developments in the field of microtechnology in biotechnology will be given. Special attention will be paid on the application of microreactors in this field.

microreactor, microreactor application, biotransformation

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