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than that of the native polysaccharide. The
antimicrobial activity of the oligosaccha-
rides is superior owing to the increase in the
free amino groups by the enzymatic depoly-
merization (Kumar and Varadaraj, 2004).
Lim and Hudson (2004) synthesized a
novel fibre-reactive chitosan derivative in
two steps from a chitosan of low molecular
weight and low degree of acetylation. First,
a water-soluble chitosan derivative, N-[(2-
hydroxy-3-trimethylammonium) propyl]
chitosan chloride (HTCC), was prepared
by introducing ammonium salt groups on
the amino groups of the chitosan. This
derivative was modified by the introduc-
tion of functional (acrylamidomethyl)
groups, which can form covalent bonds
with cellulose under alkaline conditions,
on the primary alcohol groups (C-6) of the
chitosan backbone. The fibre-reactive chitosan
derivative, O -acrylamidomethyl-HTCC (NMA-
HTCC), caused a complete inhibition in
proliferation of S. aureus and E. coli (Fig.14.3).
The derivative can be covalently bonded to
textile fibres for its use as an antimicrobial
agent in the textile industry.
The synthesis of the guanidinylated
chitosan derivatives with different molecu-
lar weights by the guanidinylation reaction
of chitosan with aminoiminomethanesul-
fonic acid (AIMSOA) has also been reported.
The antibacterial activity of guanidinium
derivatives was evaluated against S. aureus,
Bacillus subtilis, E. coli and Pseudomonas
aeruginosa. Compared with chitosan, the
chitosan derivatives presented a higher anti-
bacterial activity. The antibacterial activity
of guanidinylated chitosan enhanced with
pH decrease (Hu et al ., 2007).
Qin and collaborators (2006) prepared dif-
ferent samples of chitosan with different
molecular weights by depolymerization
with hemicellulase and water-soluble half
N-acetylated chitosan samples by N-acetylation
CH 3
Cl -
N +
CH 2
CH
CH 2
CH 3
CH 2 OH
CH 2 OH
O
O
CH 3
O
O
O
HO
HO
NH 2
NH
n
n
Cl -
CH 3
Chitosan
N +
CH 3
CH 2
CH
CH 2
HTCC
OH
CH 3
O
H
O
CN OH
CH
CH 2
CH 2
CH
CH 2
N
C
CH 2
O
O
O
HO
NH
n
Cl -
CH 3
N +
CH 3
CH 2
CH
CH 2
OH
CH 3
NMA-HTCC
Fig. 14.3. Synthesis of N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) and
O-acrylamidomethyl (NMA)-HTCC.
 
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