Biocatalysts are biological molecules capable of catalysing chemical reactions. Their use
offers numerous advantages, such as high specificity, mild reaction conditions, and
environmental sustainability, making the technology essential in the modern chemical
and biotechnological industries. The conditions that biocatalysts (usually enzymes) are
exposed to in each process are generally harsher than physiological ones. Therefore,
various techniques for stabilizing biocatalysts are used. One key strategy is their
immobilization, which attaches them to an insoluble, inert material, reinforcing their
structure and thus increasing their stability.
In this thesis, we compared different techniques for immobilizing biological molecules
that can be used as biocatalysts in flow systems, with special emphasis placed on
microfluidic systems. This technology is particularly interesting due to the precise control
of process variables and the high surface-to-volume ratio, which allows efficient heat and
mass transfer. The aim of the research was to evaluate the efficiency of different
immobilization methods and the stability of immobilized biological molecules in terms
of their application in continuous bioprocesses.
Packed-bed microreactors are especially interesting, although their main issue is the high
pressure drop. In the thesis, several correlations predicting the pressure drop in
microreactors were presented, along with graphs showing the pressure drop as a function
of the ratio between the sphere diameter and the cylindrical column diameter. It was found
that short and wide columns have the lowest pressure drop.
In the experimental part, we tested the immobilization of model biological molecules,
such as enzymes, and analysed their performance and stability under flow conditions. It
turned out that immobilization in hydrogels is very effective, especially in the case of
electrodeposited hydrogels. We also examined the leaching of immobilized enzymes in
microreactors depending on different buffer systems and pH ranges, observing stronger
leaching at higher pH levels and the potential for hydrogel dissolution. This could be
utilized for the controlled release of enzymes into the reaction mixture.
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