The invention concerns a staiblizing device designed to link two vertebrae, comprising at least two chambers arranged proximate to said vertebrae, said chambers containing a shock absorbing fluid. In particular, the invention provides metallocene complexes including a bridged metallocene component linked to an unbridged metallocene component where a ligand structure of the unbridged metallocene component is linked to the bridging group of the bridged metallocene component. This particle core is then at least partially covered by a particle coating layer of a water soluble inorganic material.