The Study Of Electrochemical Sensors Based On Carbon Nanotube And Polyamidoamine

The exciting properties of poly(amidoamine) dendrimers(PAMAM), such as their controllable size, high surface functionality, internal void space, hydrophilicity, high mechanical and chemical stability. These properties result in the enhanced sensitivity, specificity, stability and reusability as ideal building blocks for electrochemical sensors. This dissertation focused on PAMAM functionalized multiwalled carbon nanotube composites. An electrochemical sensor for the detection of paracetamol based on covalent layer by layer self-assembled carboxylated multiwalled carbon nanotubes and the fourth generation poly(amidoamine) dendrimers(G4.0 PAMAM). Meanwhile, the nonenzyme hydrogen peroxide sensor was fabricated based on electrodepositing nanoparticles on the G4.0 PAMAM functionalized multiwalled carbon nanotube. The main contents were summarized as follows:1. The products of different generations G-0.5~G4.0 PAMAM were synthesized through the Michael addition and amidation reaction using ehtylenediamine and methyl acrylate. The product was characterized by FT-IR, UV and nuclear magnetic. The results showed that PAMAM was synthesized. PAMAM conductivity were tested by cyclic voltammetry. The results showed that PAMAM various generations of PAMAM conductivity are different.2. An electrochemical sensor for the detection of paracetamol(PAT) was reported employing multiwalled carbon nanotubes and the fourth generation poly(amidoamine) dendrimers(PAMAM). The strategy of this work lies on the formation of a stable covalent linkage between carboxylated MWCNTs and amine terminated G4.0 PAMAM via covalent layer-by-layer self-assembly. Under optimal conditions, the experimental results demonstrated that the constructed sensor exhibited excellent catalytic activity toward oxidation PAT, and a wide linear range from 3.0×10-7 to 2.0×10-4M was obtained with a limit of detection of 1.0×10-7M(S/N = 3). The excellent performance of electrochemical sensor was ascribed to three-dimensional network structure with well-developed nanoscale pores of(MWCNTs–G4.0)6, which provides large surface area for efficient adsorption of PAT, and accelerating the electron transfer rate of PAT.3. G4.0 PAMAM functionalized multiwalled carbon nanotube(G4.0-MWCNTs) was prepared by amidation between carboxylic acid functionalized MWCNTs and the amine terminated G4.0 PAMAM. Then a novel hydrogen peroxide(H2O2) sensor was fabricated by electrodepositing Pd nanoparticles(NPs) on the G4.0 PAMAM functionalized multiwalled carbon nanotube composites. As revealed by field emission scanning electron microscopy, The large amounts of small-sized PdNPs(30nm) could be well deposited on the surface of the G4.0-MWCNTs modified electrode. The results showed that the modified electrode exhibited excellent electrocatalytic activity towards the reduction of H2O2 with the wide linear range from 1.0×10-9 to 1.0×10-3M, and a low limit of detection 3×10-10M(S/N=3) with good selectivity and stability, and can also be applied to real samples analysis. The excellent performance of hydrogen peroxide sensor were ascribed that G4.0 PAMAM functionalized MWCNTs load large amounts of PdNPs and the synergistic amplification effect of Pd NPs and G4.0-MWCNTs.