The design of highly stable gold nanoparticles with low affinity for biomolecules present in physiological media is a central challenge in nanomedicine.  Herein  we  describe  a  simple  coating  approach  to  stabilize  gold  nanoparticles,  based  on  the formation of a monolayer of silica around nanoparticles pre-stabilized with a small amount of poly(ethylene glycol) ligands. Once the monolayer has been formed, gold nanoparticles are highly stable against adsorption of competing thiol ligands, cyanide digestion and  even  lyophilization,  and  their  surface  can  be    readily  functionalized  using  silane  coupling  agents.  When  the  coated  gold nanoparticles  are  incubated  with  fetal  bovine  serum,  protein  adsorption  is  significantly  reduced,  as  compared  to  similar  gold nanoparticles fully covered with PEG, which is the most common strategy to avoid protein corona formation.