Biomedical Engineering Reference
In-Depth Information
Fig. 11 Preparation of protein-encapsulating
g
-PGA-Phe nanoparticles
of the preservation of the protein structure. The
g
-PGA-Phe nanoparticles and protein-
encapsulating nanoparticles could be preserved by freeze-drying. The results of
cytotoxicity tests showed that the nanoparticles did not cause any relevant cell
damage. Therefore, it is expected that the
g
-PGA-Phe nanoparticles will have great
potential as multifunctional carriers in pharmaceutical and biomedical applications,
such as drug and vaccine delivery systems. Also, Portilla-Arias et al. reported prepa-
ration of nanoparticles made of alkyl esters of
g
-PGA and described their potential
application as drug and protein carriers [
98
].
3.2 Delivery of Antigens Using Nanoparticles
Antigen-loaded polymeric nanoparticles represent an exciting approach to the
enhancement of antigen-specific humoral and cellular immune responses via selec-
tive targeting of the antigen to APCs [
99
,
100
]. DCs are considered to be initiators
and modulators of immune responses and are capable of processing antigens
through both major histocompatibility complex (MHC) class I and II pathways.
Immature DCs encounter pathogens (e.g., virus or bacteria), antigens, or particulate
materials at the injection site and, after phagocytosis, the foreign bodies taken up
into the DCs present antigens on MHC class II molecules or even on MHC class I
molecules by cross-priming [
101
]. Therefore, the antigen delivery to DCs is of key
importance in the development of effective vaccines (Fig.
12
).
