Dendrimer-mediated formation of multicomponent nanospheres

Silica encapsulation of nanoparticles has had important applications in areas as diverse as catalyst support in heterogeneous processes to controlled drug release. Current methods of production often require stringent conditions which can lead to degradation of the encapsulated material. Recently, we have developed a dendrimer-driven biomimetic approach to nanoparticle silica formation that occurs at ambient conditions. Extending this chemistry, PAMAM dendrimers have been utilized successfully as both a host for Au-0 nanoparticle synthesis and an active agent for silica condensation. The resulting product yields mesoporous silica nanospheres of 80-nm diameter supporting randomly distributed gold nanoparticles. Alternately, the positively charged surface of the dendrimers may. be used to form an electrostatic precursor complex with low ratios of negatively charged CdSe/ZnS core shell semiconductor nanoparticles (AMP dots) that condense silica, trapping the AMP dots within 200-nm diameter silica nanospheres. These separate routes to the formation of silica nanocomposites demonstrate the potential versatility of the dendrimer platform for materials synthesis.