Biomedical Engineering Reference
In-Depth Information
FIGURE 10.8
TEM image of a bovine platelet covered with PDDA/PSS/PDDA
+
(silica/PDDD)
2
indicat-
ing the platelet surface is totally covered with 78 nm silica. (From Ai, H., Fang, M., Jones, S.A., and Lvov, Y.,
Biomacromolecules
, 3, 560-564, 2002. With permission.)
10.6 CONCLUSIONS
1. LbL self-assembly is a simple and reliable method for nanocoating of any surfaces with
organized multilayers of known architectures with precisely located layers of polymers,
proteins, nanoparticles, and DNA. A fi lm thickness may be from fi ve to hundreds of nano-
meters, and they may be deposited on surfaces of any shape and area. Such coating may
modify the surface of a support, for example, to vary its wettability from super-hydrophobic
to super-hydrophilic. Specifi c features to provide biocompatibility and promotion or prevent
cell growth can be developed. This approach is prospective for coating of nonhomogenous
biological surfaces, including blood vessels and bones, as well as for biocompatible coating
of medical implants.
2. An application of LbL self-assembly to micro- and nano-cores allowed encapsulation
of tiny cores such as drug microparticles, biological cells, and viruses. Therefore, such
coating enables the controlled release of materials from microcores (drug) and the chang-
ing of their surface properties, providing enhanced colloidal stability and protection of the
interior against microbial attacks, proteolytic agents, and oxidation.
3. An LbL assembly of shells on microcores that are later dissolved (weakly cross-linked
cores or inorganic cores such as MnCO
3
) enabled production of empty microshells with
semipermeable walls of 20-100 nm thickness and diameter from 50 to 5000 nm. This
micro- or nanocapsules may be loaded with proteins or DNA for targeted and controlled
delivery. Besides, polymeric replicas of biological cells and viruses may be produced.
4. Architectural micro- and nanoshell sensors based on smart location design of fl uorescent
indicators (usually in the core) and enzymatic detection layers (usually in the outer shell)
enabled production of simple biocolloids capable for semiquantitative detection of glucose,
lactose, urea, and other materials, which are specifi c substrates for the corresponding bio-
catalytical reactions.
