Article

Laser photolysis of carboxymethylated chitin derivatives in aqueous solution. Part 2. Reaction of OH* and SO4*- radicals with carboxymethylated chitin derivatives.

Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, Shirakata-Shirane 2-22, Tokai-mura, Naka-gun, Ibaraki-ken, 319-1188 Japan.
Biomacromolecules (impact factor: 5.48). 5(2):458-62. DOI:10.1021/bm0342739
Source: PubMed

ABSTRACT The reactions of OH* or SO4*- radicals with carboxymethyl chitin (CM-chitin) and its deacetylated product, carboxymethyl chitosan (CM-chitosan), were investigated in aqueous solutions using a laser photolysis technique. The rate constants of the reactions of OH* and SO4*- radicals with CM-chitosan are always higher than those for CM-chitin, indicating that the amino-group could increase the reactivity of carboxymethylated chitin derivatives. The rate of the reactions of CM-chitin and CM-chitosan with OH* radical was found to decrease at lower pH when polymers chains tend to the coiled conformation. In comparison, the rate constant of the reaction of SO4*- radicals with CM-chitin or CM-chitosan decreased with pH, indicating that CM-chitin or CM-chitosan has a higher reactivity with the SO4*- radical at low pH due to the protonation of the amino group.

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    Article: Noncovalently modified carbon nanotubes with carboxymethylated chitosan: a controllable donor-acceptor nanohybrid.
    Dewu Long, Guozhong Wu, Guanglai Zhu
    [show abstract] [hide abstract]
    ABSTRACT: We report here the modification of multiwalled carbon nanotubes (MWNTs) with a kind of polysaccharide, carboxymethylated chitosan (cmCs), and their potential usage as donor-acceptor nanohybrids. The modified composites (cmCs/MWNTs) were characterized by high-resolution TEM, FT-IR, TGA and time-resolved spectroscopy. The time-resolved spectroscopic experiments revealed that interfacial electron transfer readily takes place between MWNTs and surface immobilized cmCs chains. The forward electron transfer is fast (< 20 ns) while the backward recombination is slow. The recombination process strongly depends on the chain length of carboxylmethylated chitosan, i.e. a shorter recombination lifetime (~1.1 micros) for the shorter-chain cmCs coated MWNTs against that of the longer-chain cmCs coated MWNTs (~3.5 micros). The results demonstrated that the cmCs/MWNTs composite may be applied as a controllable donor-acceptor nanohybrid.
    International Journal of Molecular Sciences 03/2008; 9(2):120-30. · 2.60 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

aqueous solutions
 
carboxymethyl chitin
 
carboxymethyl chitosan
 
carboxymethylated chitin derivatives
 
CM-chitin
 
CM-chitosan
 
coiled conformation
 
deacetylated product
 
higher reactivity
 
laser photolysis technique
 
low pH
 
lower pH
 
OH* radical
 
polymers chains
 
rate constant
 
rate constants
 
reactions
 
reactivity
 
SO4*- radical
 
SO4*- radicals