Janus particles

Janus particles are special types of nanoparticles whose surfaces have two or more distinct physical properties. This unique surface of Janus nanoparticles allows two different types of chemistry to occur on the same particle. The simplest case of a Janus nanoparticle is achieved by dividing the nanoparticle into two distinct parts, each of them either made of a different material, or bearing different functional groups. For example, a Janus nanoparticle may have one-half of its surface composed of hydrophilic groups and the other half hydrophobic groups. This gives these particles unique properties related to their asymmetric structure and/or functionalization. A recent comprehensive review article by Walther et al. covering all aspects from synthesis to self-assembly, novel physical properties and applications is available at Chemical Reviews.