The electrocatalytic activity of ARC CNTs can be increased after pre anodization. Wang,s group illustrated the effect of the electrochemical pretreatment of ARC and CVD prepared multi walled CNTs using nicotinamide adenine dinucleotide, ascorbic acid, hydrazine, and hydrogen peroxide model redox systems. The fact that the ARC CNTs display a marked improvement in their 2-Methoxyestradiol 2-ME2 electrochemical reactivity, which indicates that the pre anodization effectively breaks the end caps of ARC CNTs to expose new edge plane like sites. 3. Carbon Nanotube Based Electrochemical Sensors There have been many reports on CNTs based electrochemical sensors. Various electrochemical techniques . Some common techniques are voltammetry, amperometry, potentiometry, impedemetry, and conductometry, which have been described in our previous review paper.
Voltammetry, measuring the current as a response to the applied potential, is one of the most useful and widespread technique among them. For enhanced current response, it is very important to develop a stable and highly target specific interface by various surface modification of conventional electrodes. The sensitivity and the selectivity are the Masitinib crucial issues for the development of sensors for detecting biologically important molecules. Much effort has been made in the development of a highly sensitive and selective method for the detection of dopamine, which is one of the important catecholamine neurotransmitters in the mammalian central nervous system.
Conventional electrodes are not suitable for the determination of DA due to the interference from ascorbic acid and uric acid, which are co existed in a real sample at 100 times higher concentration than DA. These compounds can be easily oxidized at the similar potential of DA and thus always interfere with DA detection. The CNTs modified electrodes have been widely used to resolve this problem. Wang et al. reported the fabrication of a poly modified glassy carbon electrode coated with Nafion/SWCNTs for highly selective and sensitive determination of DA. The modified electrode enhanced the voltammetric signal of DA and effectively suppressed the interferences of AA and UA as well. A lower detection limit of 5.0 nM was achieved for DA. It was also successfully applied for the determination of DA in healthy human blood serum.
A CNT polymer composite modified electrode, with poly sodium salt and SWCNTs, were used for selective detection of DA. The negatively charged poly sodium salt attracted positively charged DA in pH 7 PBS and selectively detected it from the interference of AA. Polymer MWCNTs composite can be used for the fabrication of DA sensor. Yin et al. developed a DA sensor using cyclodextrin incorporated MWCNTs on a polyaniline modified GCE. A superior transducing property of PANI, a rapid electron transfer capability of MWCNTs, and the preconcentration by cyclodextrin showed the excellent sensitivity, selectivity, stability, and reproducibility in the determination of DA. Recently, Angeles et al. also developed an amperometric sensor for DA detection by using cyclodextrin and MWCNTs without polymer.