Biomedical Engineering Reference
In-Depth Information
Polysaccharide
PACA
FIGURE 18.1
An electron micrograph of polysaccharide-coated PACA nanoparticles. The nanoparticles
were prepared by radical polymerization of isobutylcyanoacrylate carried out with chitosan 20 kDa. The
nanoparticles were composed of a core of PIBCA and a corona of chitosan as depicted on the right image.
The nanoparticles deposited on a formvar-carbon-coated copper grid for electron microscopy were stained
with phosphotungstic acid for 30 s. Scale bar = 100 nm. Cliché: H. de Martimprey. Service commun de
Microscopie électronique, Orsay, France.
After purification, the polymer chains that were not degraded by the selective treatment of either the
PACA chains or the polysaccharide segments could be characterized as a homopolymer. This method-
ology is time consuming and needs lots of effort in validating all steps. The selectivity of the degrada-
tion methods needed to be demonstrated. It was shown that the conditions of degradation applied to
remove PACA did not modify the characteristics of the polysaccharides and vice versa. Nevertheless,
this complex procedure provided with the structures of copolymers composing polysaccharide-coated
PACA nanoparticles obtained in different conditions of synthesis. Depending on their structures, the
copolymers can be classified into two categories that depend on the type of polymerization applied to
synthesize the nanoparticles. They occurred as linear block copolymers when the nanoparticles were
prepared by radical polymerization and as comb copolymers when the synthesis of the nanoparticles
occurred by anionic polymerization (Table 18.1) (Bertholon et al., 2006b; Zandanel and Vauthier, 2012).
60
40
20
0
-20
-40
-60
Nature of the polysaccharides
FIGURE 18.2
Zeta potential of nanoparticles produced with different polysaccharides. Numbers following
the name of the polysaccharide indicates the molecular weight in kDa. White columns: nanoparticles obtained
by anionic polymerization. Black columns: nanoparticles obtained by radical polymerization. (Data from
Lira, M.C.B. et al., 2011.
Eur. J. Pharm. Biopharm
. 79:162-70; Bravo-Osuna, I. et al., 2007.
Biomaterials
.
28:2233-43; de Martimprey, H. et al., 2009.
Eur. J. Pharm. Biopharm.
71(3):490-504; Labarre, D. et al., 2005.
Biomaterials
. 26:5075 - 84.)
