Chemistry Reference
In-Depth Information
Electro deposition method
Luo and Chen et al. [143] used nanocomposite film of CNT/CS as glucose biosensor
by a simple and controllable method. One-step electro deposition method comprise a
pair of gold electrodes connects to a power supply and then dipped into the CNT/CS
solution. The pH near the cathode surface increases when solubility of CS decreases.
However, CS becomes insoluble and entrapped CNT can be deposited onto the cath-
ode surface at pH about 6.3.
Yao et al. [144] also characterized electro catalytic oxidation and sensitive electro
analysis of NADH on a novel fi lm of CS-DA-MWNTs and improved detection sen-
sitivity. In this new method, glutaraldehyde cross-linked CS-DA with the covalent
attachment of DA molecules to CS chains. Following, solution of MWNT dispersed in
CS-DA solution dropped on an Au electrode for preparing CS-DA-MWNTs fi lm and
fi nally dried.
Covalently grafting
Carboxylic acid (-COOH) groups can be covalently grafted on CNTs sidewalls by
refluxing of CNTs in acidic solution. The carboxylated CNTs then adds to aqueous
solution of CS. Grafting reactions were accomplished by N
2
purging, and then heating
to 98
o
C of CNTs/CS solution. Shieh et al. [145] compared mechanical properties of
CNTs-grafted-CS to the ungrafted CNTs. Significant improvement storage modulus
and water stability of the CS nanocomposites.
Wu et al. [146] created another process for make a CS-grafted MWNT composite.
In this different method, after preparing oxidized MWNT (MWNT-COOH), they gen-
erate the acyl chloride functionalized MWNT (MWNT-COCl) in a solution of thionyl
chloride. In the end, the MWNT-grafted-CS was synthesized by adding CS to MWNT-
COCl suspension in anhydrous dimethyl formamide. The covalent modifi cation has
improved interfacial bonding and resulted high stability of CNT dispersion. Biosen-
sors and other biological applications are evaluated as potential usage of this compo-
nent. Also, Carson et al. [147] prepared a similar composite by reacting CNT-COCl
and CS with potassium persulfate, lactic acid, and acetic acid solution at 75
o
C. They
estimated that the CNT-grafted-CS composite can be used in bone tissue engineering
because the improvement of thermal properties.
Nucleophilic substitution reaction
Covalent modification of MWNT was accomplished with a low molecular weight CS
(LMCS) by Ke et al. [148]. In this method, the acyl chloride functionalized grafted to
LMCS in DMF/Pyridine solution. This novel derivation of MWNTs can be solved in
DMF, DMAc, and DMSO, but also in aqueous acetic acid solution.
Electrostatic interaction
Furthermore, Baek et al. [149] synthesized CS nanoparticles-coated MWNTs compos-
ite by electrostatic interactions between CS particles and functionalized CNT. They
prepared CS nanoparticles and CS microspheres by precipitation method and cross
linking method respectively. The electrostatic interactions between CS particles solu-
tion in distilled deionized water and the carboxylated CNTs were confirmed by changing
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