The dual application of a Janus nanomachine provides a new concept for drug delivery. Gated mesoporous silica nanoparticles have been shown to act as reservoirs for drug storage and can release the drug in response to certain stimuli. However, an additional effector is often needed to mediate the delivery of the drug. In this context Reynaldo Villalonga, José M. Pingarrón, and their co-workers at Complutense University of Madrid and the IMDEA Nanoscience group at the University City of Cantoblanco, Spain, have developed a Janus nanoparticle with Au and mesoporous silica (MS) faces.

The Au face can be modified to act as the effector: Release of the cargo was mediated by the on-demand catalytic decomposition of urea by the enzyme urease immobilized on the Au face. A gated ensemble, which consists of a pH-responsive system, can be anchored on the pore outlets of the MS face.

The possibility to incorporate different effector molecules and gated ensembles on this type of Janus integrated nanoarchitecture opens new routes for the development of novel biologically inspired smart nanomachines for drug delivery and sensing applications.

• Enzyme-Controlled Sensing–Actuating Nanomachine Based on Janus Au–Mesoporous Silica Nanoparticles,
  R. Villalonga, P. Díez, A. Sánchez, E. Aznar, R. Martínez-Máñez, J. M. Pingarrón,
  Chem. Eur. J. 2013.
  DOI: 10.1002/chem.201300723