411
this takes place entirely in the lumen of the reproductive tract. Second, the result of
polymerization is a remarkably strong and durable protein composite, that in tensile
tests exhibited a strength of 20 MPa and stiffness of 200 MPa. Third, and most relevant,
is that polymerization occurs outside of the tissue of origin; and therefore mimicking the
sclerotization process in the laboratory seemed feasible (Koob 2002 ).
A di-catechol from creosote bush ( Larrea tridentate ), so called nordihydroguaiaretic acid (NDGA), was proposed as a biomimetic analog to
polyphenol- based biomaterial from skate egg capsules (Koob et al. 2001a , b ; Koob
and Hernandez 2002 ). NDGA has been characterized as follow:
“It caused a dose dependent increase in the material properties of reconstituted
collagen fi bers, achieving a 100-fold (!) increase in strength and stiffness over
untreated fi bers. The maximum tensile strength of the optimized NDGA treated
fi bers averaged 90 MPa; the elastic modulus of these fi bers averaged 580 MPa.
These properties were independent of strain rates ranging from 0.60 to 600 mm/
min. Fatigue tests established that neither strength nor stiffness were affected after
80 k cycles at 5 % strain.
– treated fi bers were not cytotoxic to tendon fi broblasts. Fibro- blasts attached and
proliferated on NDGA treated collagen normally. NDGA-fi bers did not elicit a
foreign body response, nor did they stimulate an immune reaction over six weeks
in vivo . The fi bers survived 6 weeks with little evidence of fragmentation or
degradation. The strength, stiffness and fatigue properties of the NDGA-treated
fi bers are comparable to those of tendon,” (Koob 2002 ; see also Koob et al.
2001a , b ; Koob and Hernandez 2003 ).
Due to tendon-like properties of NDGA treated collagen fi bers, Koob and
co- workers not exclude the development of neo-tendon by the colonizing fi broblasts
in vivo .
12.3 Conclusion
I have no doubts that bioinspiration determined by hierarchically structured composite
materials discussed in this chapter, is the driving force for development of novel
specifi cally structured biocomposites. Novel and modern techniques shed new
insights into their structural organization on a molecular level, as was shown for one
example of egg capsule collagen. As characterized by Knupp and Squire ( 2005 ),
“collagen Types IV, VI, VIII, X, and dogfi sh egg case collagen make linear and
lateral associations to form open networks rather than fi bers. The roles played by
these network-forming collagens are diverse: they can act as support and anchorage
for cells and tissues, serve as molecular fi lters, and even provide protective permeable barriers for developing embryos. Their functional properties are intimately
linked to their molecular organization,” (Knupp and Squire 2005 ). Approaches for
stabilizing materials of collagenous origin with catechol containing monomers
mimicking the biochemical situation within egg capsular layers, which were developed
in the last decade, will defi nitively be continued in the future.
12.3 Conclusion
this takes place entirely in the lumen of the reproductive tract. Second, the result of
polymerization is a remarkably strong and durable protein composite, that in tensile
tests exhibited a strength of 20 MPa and stiffness of 200 MPa. Third, and most relevant,
is that polymerization occurs outside of the tissue of origin; and therefore mimicking the
sclerotization process in the laboratory seemed feasible (Koob 2002 ).
A di-catechol from creosote bush ( Larrea tridentate ), so called nordihydroguaiaretic acid (NDGA), was proposed as a biomimetic analog to
polyphenol- based biomaterial from skate egg capsules (Koob et al. 2001a , b ; Koob
and Hernandez 2002 ). NDGA has been characterized as follow:
“It caused a dose dependent increase in the material properties of reconstituted
collagen fi bers, achieving a 100-fold (!) increase in strength and stiffness over
untreated fi bers. The maximum tensile strength of the optimized NDGA treated
fi bers averaged 90 MPa; the elastic modulus of these fi bers averaged 580 MPa.
These properties were independent of strain rates ranging from 0.60 to 600 mm/
min. Fatigue tests established that neither strength nor stiffness were affected after
80 k cycles at 5 % strain.
– treated fi bers were not cytotoxic to tendon fi broblasts. Fibro- blasts attached and
proliferated on NDGA treated collagen normally. NDGA-fi bers did not elicit a
foreign body response, nor did they stimulate an immune reaction over six weeks
in vivo . The fi bers survived 6 weeks with little evidence of fragmentation or
degradation. The strength, stiffness and fatigue properties of the NDGA-treated
fi bers are comparable to those of tendon,” (Koob 2002 ; see also Koob et al.
2001a , b ; Koob and Hernandez 2003 ).
Due to tendon-like properties of NDGA treated collagen fi bers, Koob and
co- workers not exclude the development of neo-tendon by the colonizing fi broblasts
in vivo .
12.3 Conclusion
I have no doubts that bioinspiration determined by hierarchically structured composite
materials discussed in this chapter, is the driving force for development of novel
specifi cally structured biocomposites. Novel and modern techniques shed new
insights into their structural organization on a molecular level, as was shown for one
example of egg capsule collagen. As characterized by Knupp and Squire ( 2005 ),
“collagen Types IV, VI, VIII, X, and dogfi sh egg case collagen make linear and
lateral associations to form open networks rather than fi bers. The roles played by
these network-forming collagens are diverse: they can act as support and anchorage
for cells and tissues, serve as molecular fi lters, and even provide protective permeable barriers for developing embryos. Their functional properties are intimately
linked to their molecular organization,” (Knupp and Squire 2005 ). Approaches for
stabilizing materials of collagenous origin with catechol containing monomers
mimicking the biochemical situation within egg capsular layers, which were developed
in the last decade, will defi nitively be continued in the future.
12.3 Conclusion