Halloysite Nanotubes as Biomimetic Nanoreactors

Abstract

Halloysite, a naturally occurring, 50-nm-diameter tubular material, has been utilized as a new biomineralization nanoreactor to form urease-catalyzed CaCO3. The CaCO3 synthesis occurs exclusively inside the halloysite nanotubes, with no carbonate found on the outer surface of the nanotubes or in solution. Precipitated CaCO3 completely fills the inner nanotube lumen (see picture) and exhibits the metastable vaterite phase structure.