Reducing Protein Corona Formation and Enhancing Colloidal Stability of Gold Nanoparticles by Capping with Silica Monolayers

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.