Bacterial Cellulose and Its Polymeric Nanocomposites - The Nanoscience and Technology of Renewable Biomaterials - page 249

0.25

Aorta Circ
Aorta Axial
P15 BC0.3-Cycle 2
P10 BCE0.15-Cycle 3

0.20

0.15

0.10

0.05

0.00

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Strain

Figure9.17 Closematchofstress-straincurveofvariousnanocompositeswithporcineaorta
incircumferentialandaxialdirections(28).(Journal of Biomedical Materials Research, Part B:
Applied Biomaterials, 79B (2), 2006, 245-53. Copyright 2006 JohnWiley&Sons, Inc. Re-
printedwithpermissionof JohnWiley&Sons, Inc.)

determined that a degree of substitution of 7 groups on 10 glucan (DS of 0.7) and a DP
of 80 was the most effective in disrupting glucan chain association to produce separate,
smaller size microfibrils (44). In this case the average size of the cellulose microfibrils
is reduced to 10 nm with 1% CMC concentration.
Since the first observation that additives in the BC incubation medium may alter the
aggregation and crystallization pattern of bacterial cellulose (43), a wealth of studies
have reported on the effect of polymers on bacterial cellulose crystallization with a view
to understanding the biosysnthesis of the cell wall (29, 35, 37, 44-55). For example
hemicelluloses have been shown to alter the aggregation of BC chains into microfibrils
and ribbons resulting in smaller width fibers and a crystalline structure that is enhanced
in the I β form to the detriment of the I α form (47-52, 54, 55). In contrast pectin
has been found to have little effect on the morphology and microstructure of BC (51).
Although such studies are principally aimed at shedding light on cellulose biosynthe-
sis, they have also paved the way for the development of BC nanocomposites using
biomimetic approaches. In a biomimetic approach, the BC is grown in a media that is
rich in another polymer such that BC and the host polymer assemble in nanocomposites.
As pointed out by Teeri et al . (56) biomimetics can largely contribute to the develop-
ment of novel environmentally friendly biomaterials owing to the energy efficient and
mild conditions nature uses for the biosynthesis of biomaterials. The work by Gidley's