Solid phase gold nanoparticle synthesis

A method of synthesizing ligand-conjugated gold nanoparticles (AuNPs), comprising:

• providing amine-modified silica particles;
• providing a solution comprising HAuCl4;
• suspending the amine-modified silica particles in the solution comprising the HAuCl4;
• producing silica particles-NH3+AuCl4− complexes by allowing Au3+ ions in the solution to be adsorbed and/or immobilized onto the surface of the amine-modified silica particles, wherein the solution has no mesoporous silica nanoparticles (MSN) present;
• exposing the silica particles-NH3+AuCl4− complexes to radiation to reduce the Au3+ ions and obtain bare gold nanoparticles (AuNPs) adsorbed and/or immobilized onto the surface of the amine-modified silica particles, wherein the bare AuNPs are without organic surface modifications;
• and
• reacting a ligand with the bare AuNPs adsorbed and/or immobilized onto the surface of the amine-modified silica particles under sonication to desorb and modify the bare AuNPs and thereby synthesizing the ligand-conjugated gold nanoparticles.