Biomedical Engineering Reference
In-Depth Information
with a cyclic anhydride or by the amide coupling of two amino acids
with a diacid chloride.
∑ Branched polyanhydrides.
∑ Crosslinked polyanhydrides with three dimensional networks, showing
high mechanical strength and a slow degradation rate.
The properties of polyanhydrides can be modified by changing polymer
composition and structure. This is obtained by realizing copolymers, polymer
blends, crosslinking between chains, partial hydrogenation and reaction with
epoxides. low molecular weight Pla, PHB and PCl are miscible with
polyanhydrides whereas high molecular weight polyesters are not.
Polyanhydrides have been investigated as potential materials suitable
for controlled-release devices of drugs, chemotherapeutic agents, local
anesthetics, anticoagulants, neuroactive drugs, and anticancer agents, since
the
in vivo
compatibility is very good (lanza
et al.
, 2007). representative
polyanhydrides are poly(1,3-bis-
p
-carboxyphenoxypropane anhydride) (PCPP)
and its copolymers with sebacic acids (PCPP-sa) (Fig. 1.11).
indeed, PCPP-sa systems were clinically tested in order to deliver an
anticancer agent into the brain for the treatment of brain neoplasm in rats,
rabbits and monkeys, showing a satisfactory biocompatibility without adverse
effects (Domb
et al.
, 1997). nowadays, this material is FDa approved and
is currently in clinical use for the treatment of brain cancer (lanza
et al.
,
2007).
1.4 Poly(ortho esters)
Poly(ortho esters) (POe) contain ortho ester groups along the chain; an
ortho ester is a functional group containing three alkoxy groups attached to
one carbon atom. Degradation results from a hydrolysis mechanism. These
polymers can be formulated in order to obtain a surface erosion degradation.
O
O
*
O
O
C
H
2
O
3
n
(a)
O
O
O
O
O
*
O
C
H
2
C
H
2
O
O
*
6
3
y
x
(b)
1.11
(a) PCPP and (b) PCPP-SA.
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