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Chitin, chitosan and bacterial cellulose for textiles 303

suitable for these diverse applications some modifications of the fi bres such
as acetylation process (Barud et al., 2008) or forming composite with other
materials (Pommet et al., 2008; Wan et al., 2006) have been reported.

12.4.3 Bacterial cellulose–chitosan blends

Since the chemical structure of the chitosan backbone is very similar to that
of cellulose, it was expected that chitosan could be miscible with cellulose
and the blending might improve the mechanical and biological properties
of the developed material. Ciechanska (2004) reported on the modifi cation
of bacterial cellulose during microbiological synthesis by introducing
selected bioactive polysaccharides, such as various chitosan forms and their
derivatives, into the culture medium. This led to the incorporation of glu-
cosamine and N-acetylglucosamine units in the cellulose chains. The modi-

fied bacterial cellulose consists of microfibres having diameters in the order
of tenths of micrometer that form a 3D network and are characterized by
excellent moisture-retaining properties. Such features make bacterial cel-
lulose/chitosan a dressing material suitable for treatment of various kinds
of wounds, burns and ulcers. The same method has been exploited recently
to produce bacterial cellulose–chitosan films (Phisalaphong and Jatupai-

boon, 2008). Modifying bacterial cellulose by adding 0.25–0.75 (% w/v) of
chitosan (85% DAC) of MW 30 000 and 80 000 in the culture medium
during biosynthesis by A. xylinum provided improved mechanical proper-
ties in the wet and the dry state, and large water absorption capacity and
average surface area.

12.5 Advantages and limitations
Chitin, chitosan and bacterial cellulose are natural biopolymers with numer-
ous intrinsic properties for various applications. The natural abundance of
chitin and its derivative chitosan in combination with their biocompatibility,
biodegradability, antimicrobial activity and non-toxicity is a reason for
increased interest in their exploitation, especially in biomedical and phar-
maceutical applications. It is expected that electrospinning will become the
method of choice for the production of chitin and chitosan fi bres. The major
advantage of this method is the ability to produce long and continuous

nanofibres in a cost-effective way, which makes it attractive for industrial-
ization. However, as in all nanotechniques, its low productivity is an impor-
tant disadvantage. In order for electrospinning to be commercially viable,
it is essential to increase the production rate of the nanofi bres. The other
major constraint for large-scale production of pure chitin and chitosan
nanofibres still remains the selection of appropriate non-aggressive and

non-toxic solvents.

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