Spontaneous Formation of Gold Nanoparticles with Octa(3-aminopropyl) Polyhedral Oligomeric Silsesquioxane

Mixture of octa(3-aminopropyl) polyhedral oligomeric silsesquioxane (POSS-NH2) and tetrachloroauric(III) acid under basic condition spontaneously produced gold nanoparticles (AuNPs). The amino groups reduced Au(III) cation to Au(0) and interacted with the surface of AuNPs; POSS-NH2worked as a reductant and a stabilizer at once. Sodium hydroxide partially hydrolyzed Si–O bonds of polyhedoral oligomeric silsesquioxane (POSS) to generate SiO−species, which stabilized AuNPs via electrostatic interparticle repulsion to avoid aggregation. Addition of hydrochloric acid neutralized the amino groups of POSS-NH2, and generated NH3+interacted with SiO−to form aggregates. That is, pH-responsive AuNPs were prepared through the facile method.