Selective grafting of proteins on Janus particles: Adsorption and covalent coupling strategies

Janus particles have proven to be original particles to sense protein–cell interactions or to organize cell on a substrate. This work presents a covalent coupling strategy to graft fibronectin on a specific side of Au/PS or Au/SiO2 1 μm Janus particles. By studying several buffers that could limit adsorption of protein on plain particles of PS, SiO2 and Au, fibronectin is covalently grafted on those particles. We demonstrate two ways of grafting proteins on one side of the Janus particles, either on the Au side functionalized with thiols or on the PS/SiO2 side activated with carboxylate groups.