Bioactive MIL-88A Framework Hollow Spheres via Interfacial Reaction In-Droplet Microfluidics for Enzyme and Nanoparticle Encapsulation

Functional bio-MOF hollow spheres with controlled size in the 35–2000 μm range were successfully synthesized by interfacial reaction using a continuous-flow droplet microfluidic system in a single step and one-flow strategy. The architecture of MIL-88A frameworks was extended from single-shell to double-shell hollow spheres. Moreover, various functional nanoparticles (silica, cobalt, and UiO-66(Zr) MOF) were directly encapsulated in the single-shell hollow spheres, while maintaining the functionality of the cargo. In particular, three kinds of enzymes (glycerol dehydrogenase, horseradish peroxidase, and acetylcholinesterase) were also encapsulated inside the single-shell hollow spheres under mild conditions. The catalytic activity and the superior recyclability of the encapsulated enzymes were demonstrated against free enzymes.