Enhanced enzymatic reaction by aqueous two-phase systems using parallel-laminar flow in a double Y-branched microfluidic device

Although there are several reports showing the employment of aqueous two-phase systems (ATPS) for biotransformation in large-scale, the industrial application of ATPS is still hampered by their drawbacks such as slow diffusive mass transfer, long settling time for phase separation, and batch processes. Here, we propose for the first time a continuous-flow process based on a suitably designed ATPS parallel-laminar flow in a double Ybranched microfluidic device using for enzymatic catalysis. In a model urease reaction, polyethylene glycol (PEG) 8 kDa and dextran (Dex) 500 kDa are selected as polymer solutions, in which the enzymes settle mainly in the Dex phase while the products partition mainly to the PEG phase during short residence time. On account of rapid micro-transport, as well as integrate one single step of biocatalysis and separation process, obvious intensification of enzymatic catalysis in such ATPS microfluidic platform is demonstrated. Compared with the conventional ATPS in a beaker under gentle stirring, the enzymatic reaction rate in ATPS microfluidic is 500 times higher. Furthermore, the effects of flow rates, substrate concentration, residence time, and recycling number on the reaction rate and conversion rate are evaluated, respectively. Our study provides an all-aqueous, micro-scale and coupled reaction-separation platform for the process intensification of enzymatic catalysis, which has not only theoretical significance, but also practical value for biotransformation-based fields, such as biomedical, pharmaceuticals and food applications.