Biomedical Engineering Reference
In-Depth Information
and Feng, 2006). Recently, silk and silk-based materials have attracted renewed inter-
est, because of their biological applications. According to early records, silk fibers
have been used for wound closure by surgeons for at least 3,000 years.
The biomedical applications of silk protein have been studied since the 1960s. The
excellent biocompatibility and functionality of silk has led to the development of vari-
ous biomedical devices (Altman et al., 2003; Vepari and Kaplan, 2007; Wang et al.,
2006). For example, in the early era of silk biomaterials, many researchers developed
silk films and sponges as would dressing (Fini et al., 2005; Roh et al., 2006). Recent
studies reported the use of silk in oral administration (Oh et al., 2007). The biological
applications for silk now include tissue engineering scaffolds (Moreau et al., 2006;
Nazarov et al., 2004), nerve conduits (Yang et al., 2007), and artificial ligaments (Fan
et al., 2008). The biocompatibility and functionality of silk is similar to collagen, and
the physical and mechanical properties of silk make it suitable in biomedical devices.
Silks from silkworms and orb-weaving spiders have impressive mechanical proper-
ties (Table 1), in addition to environmental stability, biocompatibility, controlled pro-
teolytic biodegradability, morphologic flexibility and the ability for amino acid side
change modification to immobilize growth factors (Altman et al., 2003; Arai et al.,
2001; Fuchs et al., 2006; Horan et al., 2005; Hu et al., 2006; Karageorgiou et al., 2004;
Kim et al., 2005; Li et al., 2006; Minoura et al., 1995; Motta et al., 2004; Vepari and
Kaplan, 2006; Wong Po Foo and Kalpan, 2002).
table 1.
Mechanical properties of biodegradable polymeric materials (Arai et al., 2001).
Strain (%) at
break
Source of biomaterial
Modulus (GPa)
UTS (MPa)
References
(Perez-Rigueiro et al.,
2000)
B. mori
silk (with sericin)
5-12
500
19
(Perez-Rigueiro et al.,
2000)
B. mori
silk (without sericin)
15-17
610-690
4-16
B. mori
silk
10
740
20
(Cunniff et al., 1994)
N. clavipes
silk
11-13
875-972
17-18
(Cunniff et al., 1994)
Collagen
0.0018-0.046
0.9-7.4
24-68
(Pins et al., 1997)
Cross-linked collagen
0.4-0.8
47-72
12-16
(Pins et al., 1997)
(Engelberg and Kohn,
1991)
Polylactic acid
1.2-3.0
28-50
2-6
Zhen-ding et al. (2009) suggested that combining the advantages of SF and chi-
tosan, the SFCS scaffold should be a prominent candidate for soft tissue engineering,
especially liver tissue engineering (Zhen-ding et al., 2009). It has been reported that
chitosan could induce the conformational transition of SF from a random coil to a
b-sheet structure (Park et al., 1999) and a polymer blend of these two biopolymers
could also form a hydrogel having a semi-interpenetrating polymer network by using
glutaraldehyde as a crosslinking agent (Kweon et al., 2001).
Search WWH ::
Custom Search