The design and synthesis of a new class of gold nanoparticle with guanosine monophosphate derivatives or G-rich oligonucleotides as their surface ligands are described. These nanoparticles spontaneously form macroscopic assemblies at low temperature and relatively high salt concentrations, which is attributed to the cooperative formation of guanosine quartets and G-quadruplexes between the individual nanoparticles. Significantly, the solution behavior of these nanoparticles is highly controllable by adjusting solution parameters (including temperature, ionic strength, and ion species) and the sequence of the G-rich oligonucleotide