Glassy Carbon Electrode Modified with Hybrid Nanofibers Containing Carbon Nanotubes Trapped in Chitosan for the Voltammetric Sensing of Nicotine at Biological pH.

In this paper, Nicotine (NIC) was detected by cyclic voltammetry (CV) using a modified glassy carbon electrode (GC). To do this, the surface of the GC electrode was modified by hybrid Nanofiber obtained from electrospinning method. Hybrid nanofibers were produced through the dispersion of carboxylated Multi-walled carbon nanotube (MWCNT-COOH) as an inorganic component in the CS polymer matrix as an organic component. The nanofibers showed unique morphology and high surface area value. With the increase of functionalized carbon nanotube content in the nanofibers, the mean pore diameter and the average nanofiber diameter increased. The electrochemical properties of nanofibers toward the sensing of NIC were investigated by cyclic voltammetry method. NIC was irreversibly reduced with the use of CS/MWCNT-COOH electrode, a controlled process with 2 protons and 2 electrons. An oxidation signal at lower potential with higher current was obtained for nicotine with the use of polymer-modified electrode compared to glassy carbon electrode. This was implied on the electrocatalytic effect of the hybrid nanofibers due to the ability of carbon nanotubes to increase the rate of electron transfer. At optimum conditions the oxidation of NIC was occurred at 0.82 eV with a pH of 7.4. The linear calibration curve was in the concentration range of 0.1 to 100 μM NIC (R2= 0.9987) with a detection limit of 30 nM. For 100 parallel 10 μM NIC diagnoses for 5 replicates, 97.2% with a standard deviation of 4.08 maintained their stability over the first cycle. This indicates that the CS/MWCNT-COOH electrode has excellent reproducibility and stability.