10 2 Nanoparticles – Nanocomposites
coagulation of two zirconia particles. As the process of coagulation was incomplete, there are concave regions of the zirconia core visible. During the coating
process, these concave areas were filled with alumina; therefore, finally, the coated
particle has only convex surfaces. This minimizes surface energy; an important
principle acting in any type of nanomaterial.
As already mentioned above, multifunctional particles are widely used in biology
and medicine. For this application, it is necessary to add proteins or other biological molecules, which are characteristic of cells, where the particle should attach at
the surface of the particles. Biological molecules are attached at the particles only
via specific types of molecules, accommodated in the outermost coupling layer [4].
The development of these coupling layers is one of the crucial points for this
application. Figure 2.5 displays such a biologically functionalized particle. The
Figure 2.4 Three typical examples of
nanocomposite particles. In (a), a crystallized
ceramic core (ZrO 2 ) is coated with an
amorphous ceramic layer (Al 2 O 3 ). It is also
possible (b) to coat a ceramic core (Fe 2 O 3 )
with a polymer. Coating a ceramic core (TiO 2 )
with a thin metal (Pt) layer (c) is impossible
because of the difference in the surface
energies. In such a case, tiny metal clusters
decorate the ceramic particles [1, 3].
(a, b: Reproduced with permission by Elsevier;
c: Vollath, Szabó unpublished results.)
10 nm
5 nm
10 nm
(a)
(b)
(c)
Figure 2.5 Nanocomposite particle for
application in biology or medicine. The
ceramic core may be magnetic, luminescent,
or even bifunctional. The cell or tumorspecific proteins or enzyme at the surface,
necessary for coupling of the particle at the
intended type of cells, need a coupling layer
as; in general, these molecules cannot be
attached directly at the ceramic surface.
Ceramic
core
Coupling layer
Cell or tumorspecific protein
coagulation of two zirconia particles. As the process of coagulation was incomplete, there are concave regions of the zirconia core visible. During the coating
process, these concave areas were filled with alumina; therefore, finally, the coated
particle has only convex surfaces. This minimizes surface energy; an important
principle acting in any type of nanomaterial.
As already mentioned above, multifunctional particles are widely used in biology
and medicine. For this application, it is necessary to add proteins or other biological molecules, which are characteristic of cells, where the particle should attach at
the surface of the particles. Biological molecules are attached at the particles only
via specific types of molecules, accommodated in the outermost coupling layer [4].
The development of these coupling layers is one of the crucial points for this
application. Figure 2.5 displays such a biologically functionalized particle. The
Figure 2.4 Three typical examples of
nanocomposite particles. In (a), a crystallized
ceramic core (ZrO 2 ) is coated with an
amorphous ceramic layer (Al 2 O 3 ). It is also
possible (b) to coat a ceramic core (Fe 2 O 3 )
with a polymer. Coating a ceramic core (TiO 2 )
with a thin metal (Pt) layer (c) is impossible
because of the difference in the surface
energies. In such a case, tiny metal clusters
decorate the ceramic particles [1, 3].
(a, b: Reproduced with permission by Elsevier;
c: Vollath, Szabó unpublished results.)
10 nm
5 nm
10 nm
(a)
(b)
(c)
Figure 2.5 Nanocomposite particle for
application in biology or medicine. The
ceramic core may be magnetic, luminescent,
or even bifunctional. The cell or tumorspecific proteins or enzyme at the surface,
necessary for coupling of the particle at the
intended type of cells, need a coupling layer
as; in general, these molecules cannot be
attached directly at the ceramic surface.
Ceramic
core
Coupling layer
Cell or tumorspecific protein