Recently, enzymes have been recognized as a new class of smart
nanomaterials in the areas of regenerative medicine, drug delivery,
and diagnostics. In this study, we applied the hydrolytic enzyme
“urease” as a nanoreactor for the room temperature synthesis of
silica particles. An advantage of this biomolecular template is that
the local pH around the enzyme particle can be controlled by the
hydrolysis of urea (Fig. 1). Primarily, the production of ammonia
by the enzyme fine tunes the local pH at the template surface
such that it is appropriate for the growth of silica particles. First,
preliminary experiments established the minimal concentration
of urea required for acceptable biomineralization yields of the
silica–urease composites. The yield of particle formation increases
as the initial urea concentration is increased.