Two-phase biocatalysis is commonly used for the bioconversion of water-insoluble chemical and pharmaceutical compounds. In research laboratories, such processes often take place in flasks and are driven and limited by slow diffusive processes. In this work, we developed droplet-based microfluidic systems and used them to perform testosterone dehydrogenation. The use of microdroplets as reaction vessels offers the advantage of greatly improved diffusion rates due to significantly increased surface-to-volume ratio. We found that indeed reaction time was reduced from tens of minutes to tens of seconds without sacrificing conversion efficiency. This demonstrates the potential of droplet-based two-phase biocatalysis
