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a good candidate for developing innovative devices for neural repair. Yet, in vivo exper-
imental studies have shown that chitosan can be successfully used to create scaffolds
that promote regeneration both in the central and in the peripheral nervous system. In
this review, the relevant literature on the use of chitosan in the nervous tissue, either
alone or in combination with other components, is overviewed. Altogether, the prom-
ising in vitro and in vivo experimental results make it possible to foresee that time for
clinical trials with chitosan-based nerve regeneration-promoting devices is approaching
quickly.
1. INTRODUCTION
Chitin and its main derivative, chitosan, are becoming increasingly
relevant among the novel families of biomacromolecules because of their
wide potential application in biomedicine and tissue engineering
( Domard & Domard, 2002 ; Khor & Lim, 2003; Kumar, 2002; Singh &
Ray, 2000 ; Suh & Matthew, 2000 ).
Chitin and chitosan represent a family of linear polysaccharides made up
of b (1-4)-linked N -acetyl D -glucosamine and D -glucosamine units
( Domard &Domard, 2002; Muzzarelli, 1977 ). Depending on the processing
method used to derive the biopolymer, glucosamine units may be randomly
or block distributed throughout the biopolymer chain.
Chitin is primarily obtained from the exoskeleton of arthropods, shellfish
such as crabs and shrimps, cuticles of insects, and cell wall of fungi
( Muzzarelli, 1977 ). Based on the chain organization in sheets or stacks, chi-
tin can be classified into three crystalline isoforms: a , b , and g . The structure
of a -chitin has been investigated more extensively than that of either the b
or the g form, because it is the most common polymorphic form. Commer-
cial chitins are usually isolated from marine crustaceans, because of large
amount of waste derived from food processing. In this case, a -chitin is pro-
duced while squid pens are used to produce b -chitin ( Aranaz et al., 2009 ).
Crustacean shells consist of proteins, calcium carbonate, chitin, and contain
pigments such as carotenoids. Chitin is extracted by acid treatment to dis-
solve the calcium carbonate followed by alkaline extraction to dissolve
the proteins and by a depigmentation step to obtain a colorless product
( Aranaz et al., 2009; Muzzarelli, 1977 ).
Chitosan, on the other hand, although occurring in some fungi
(Mucoraceae), is produced industrially by cleavage of the N -acetyl groups
of the chitin N -acetyl D -glucosamine residues ( Muzzarelli, 1977 ).
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