In contrast, a new concept for entrapping
enzymes using a biosilification process has been reported by
Naik et al. [29]. In nature, diatoms are able to synthesize silica
nanoparticles by polymerization of silicic acid, catalyzed by enzymes
known as silicateins. When this process is performed in
the presence of an enzyme it results in the entrapment of silica
[31]. Meanwhile, nanoporous silica spheres with a surface
area of 630 m2g−1 and mesopores with pore sizes up to 40 nm,
and a subsequently assembled nanocomposite shells, composed
of three layers of poly-dimethyldiallylammonium chloride and
21-nm silica nanoparticles, has been reported for enzyme immobilization
[32]. These biomimetic silica nanoparticles and
nanoporous silica spheres can generally provide a large surface
area and lowmass-transfer resistance arisen fromnanostructure,
for useful enzyme stabilization.