Enzyme-controlled sensing-actuating nanomachine based on Janus Au-mesoporous silica nanoparticles.

Novel Janus nanoparticles with Au and mesoporous silica faces on opposite sides were prepared using a Pickering emulsion template with paraffin wax as the oil phase. These anisotropic colloids were employed as integrated sensing-actuating nanomachines for enzyme-controlled stimuli-responsive cargo delivery. As a proof of concept, we demonstrated the successful use of the Janus colloids for controlled delivery of tris(2,2'-bipyridyl) ruthenium(II) chloride from the mesoporous silica face, which was grafted with pH-sensitive gatelike scaffoldings. The release was mediated by the on-demand catalytic decomposition of urea by urease, which was covalently immobilized on the Au face.