Sucrose Hydrolysis in a Bespoke Capillary Wall-Coated Microreactor

Microscale technology has been increasingly used in chemical synthesis up to production scale, but in biocatalysis the implementation has been proceeding at a slower pace. In this work, the design of a low cost and versatile continuous flow enzyme microreactor is described that illustrates the potential of microfluidic reactors for both the development and characterization of biocatalytic processes. The core structure of the developed reactor consists of an array of capillaries with 450 μm of inner diameter with their inner surface functionalized with (3-aminopropyl)triethoxysilane (APTES) and glutaraldehyde where Saccharomyces cerevisiae invertase was covalently bound. The production of invert sugar syrup through enzymatic sucrose hydrolysis was used as model system. Once the microreactor assembly reproducibility and the immobilized enzyme behavior were established, the evaluation of the immobilized enzyme kinetic parameters was carried out at flow rates ranging from 20.8 to 219.0 μL·min−1 and substrate concentrations within 2.0%–10.0% (w/v). Despite the impact of immobilization on the kinetic parameters, viz. Km(app) was increased two fold and Kcat showed a 14-fold decrease when compared to solution phase invertase, the immobilization proved highly robust. For a mean residence time of 48.8 min, full conversion of 5.0% (w/v) sucrose was observed over 20 days.