Macroporous Silica Hollow Microspheres as Nanoparticle Collectors

In this work, we report the fabrication of macroporous silica hollow microspheres through a polystyrene (PS) templating route. Silica seeds are first deposited onto the surfaces of PS beads as a result of the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in a basic condition. Subsequent growth of silica seeds to nanoparticles with size of ∼ 40 nm leads to the coalescence of the adjacent particles, forming continuous two-dimensional silica networks on the PS surfaces. The uncovered areas on PS surfaces were converted into macrosized through holes after core removal through either dissolution or calcination, thus forming the macroporous silica hollow structures. The monodispersed hollow spheres were demonstrated to be efficient collectors for capturing and loading various nanoparticles, both hydrophilic and hydrophobic, from the external solutions. The functional particles loaded macroporous hollow spheres will have promising applications in biotechnology and catalysis.