Particles obtainable by the reaction of compounds which can form inorganic nanoparticles with organic molecules which comprise functional groups, and the use of these particles for the finishing of inanimate organic polymers, in particular for stabilization against the effect of UV radiation. Liquid formulations which comprise such particles, and also methods for the preparation of the particles and their liquid formulations. Powders which are obtainable from the abovementioned liquid formulations and also liquid formulations which are obtainable by redispersing the powders. Use of nanoparticles with organic light-absorbing compounds attached to the surfaces thereof for stabilizing polymers against the effect of light, free radicals or heat.