Chitosan supraparticles with fluorescent silica nanoparticle shells and nanodiamond-loaded cores.

Spherical colloidal structures with a sparsely or densely packed shell of nanoparticles have been the subject of intense research efforts for more than a decade. Research has focused on the utilization of aqueous, soft, or solid cores mainly on the micron-scale. A synthesis route that combines a stabilizing biopolymer core in combination with small (15 nm) or ultrasmall (5 nm) nanoparticles templated on the surface is still missing and pivotal to push these structures further into bionanotechnological applications. Here, we present core-shell supraparticles with a nanodiamond-loaded chitosan core and a shell assembled from fluorescent silica nanoparticles with controlled packing density which feature final sizes significantly below one micrometer. The synthesis route is highly versatile and represents a general approach for the synthesis of sophisticated supraparticles with shells formed from distinct nanoparticle shells and biopolymer cores loaded with selective nanoparticles.