Preparation And Application Of Polyethyleneimine Functionalization Of Carbon Nanotubes Modified Electrode

Carbon nanotubes (CNTs) have been used in bisensor or bio-moleculer recognition fielddue to their unique physical and chemical properties. Polyethyleneimine (PEI), as a commonpolyelectrolyte dispering agent, not only retained the stability through the polymer chain, butalso improved the dispersion of CNTs in aqueous solution after PEI functionalized CNTs.Therefore, this dissertation focused on the preparation of modified electrodes by combiningthe PEI functionalized CNTs with metal nanoparticles and their application of electrocatalysistowards bio-moleculer. The main contents were summarized as follows:1A novel hydrogen peroxide sensor was fabricated by the seed-mediated growth method.First, polyethyleneimine（PEI） functionalized multiwalled carbon nanotubes（MWNTs）were used as growth scaffold on the glass carbon electrode (GCE). Then, Au nanoparticleswere electrodeposited uniformly as seeds. Finally, Pt nanoparticles (PtNPs) grew on Aunanoparticles to form Pt@Au core-shell structure nanocomposite. A new type ofelectrochemical sensor based on Pt@Au/PEI-MWNTs nanocomposites for detection ofhydrogen peroxide was then developed, and the designed Pt@Au/PEI-MWNTs/GCE wascharacterized by electrochemical methods and field emission scanning electron microscopy(FESEM). The differential pulse voltammetry (DPV) experiment results showed that themodified electrode exhibited excellent electrocatalytic activity towards the reduction of H2O2with the wide linear range from9.2×10-8mol/L to1.3×10-3mol/L. The correlation coefficientwas0.9994and the low detection limit was3.1×10-8mol/L at the signal-to-noise ratio of3.Finally, this proposed sensor was successfully employed to determine the L-Tyr in realsamples.2A novel and simple L-Tyrosine (L-Tyr) sensor was fabricated based onpolyethyleneimine (PEI) functionalization of single-walled carbon nanotubes (SWCNTs)modified glassy carbon electrode (GCE). The modified electrode was characterized byscanning electrnic microscopy (SEM), infra-red spectrum (IR) and electrochemicalimpedance spectroscopy (EIS). Electrochemical behavior of L-Tyrosine (L-Tyr) onPEI-SWCNTs/GCE modified electrode was investigated by cyclic voltammetry (CV) anddifferential pulse voltammetry (DPV) in this paper. Experimental results showed that theoxidation potential of L-Tyr shift negatively at the modified electrode，and its oxidative peakcurrent increased obviously. Under the optimized conditions, the oxidation peak current of L-Tyr was proportional to its concentration in the range of5.9×10-6～5.3×10-4mol/L, thecorrelation coefficient was0.994and the low detection limit was2.0×10-6mol/L (S/N=3).Finally, this proposed sensor was successfully employed to determine the L-Tyr in realsamples.