Janus nanoparticles are colloidal particles combining two or more different properties at opposite sides. Luis Liz-Marzán and co-workers, Universidade de Vigo, Spain, developed a versatile and easily scalable colloid-chemistry route using these particles for the design and fabrication of Au semishells.

Pre-formed Janus silica nanoparticles are used as templates, where the growth of Au takes place selectively on amino-group functionalized areas (pictured). Partial coverage is achieved by a masking process, allowing selective functionalization on only one side of the Au semishells.

Preliminary results show that this method enables the control of the geometry of the plasmonic structures. By variation of the concentration of the surfactant didodecyldimethylammonium bromide (DDAB), the penetration of the silica particles at the wax–water interface is modulated. The variation of DDAB in the synthesis thus allows tuning of the Janus silica particle composition. Furthermore, the silica cores can be readily etched away, leading to the fabrication of hollow Au semishells.

_{Image: © Wiley-VCH}

• Colloidal Synthesis of Gold Semishells,
  D. Rodríguez-Fernández, J. Pérez-Juste, I. Pastoriza-Santos, L. M. Liz-Marzán,
  ChemistryOpen 2012, 1(2), 90–95.
  DOI: 10.1002/open.201200002

ChemistryOpen – the first society-owned, open-access, chemistry journal – is a journal of ChemPubSoc Europe published by Wiley-VCH.