Synthesis Of Multi-functionalized Carbon Nanotube Composites And Their Potential Applications In Biology

Recently, as a novel nano material, carbon nanotubes (CNTs) have attracted great attention in the biology fields due to their unique physical and chemical properties. In this thesis, the chemical modifications of CNTs have been investigated. Citric acid (CA), chitosan (CTS) and ferrous ions (Fe2+) associated with the surface cf carbon nanotubes step by step by mutli-step reactions. And they were examined using FT-IR, UV-Vis, SEM, TEM, XRD and TGA. Further more, their potential applications in biology have been discussed.Currently, the chemical modification of CNTs mainly concentrates on the acylation process by thionyl chloride after the oxidation process of CNTs (o-CNTs). Though it is efficient, the whole craft is complex and toxic. In this thesis, CA instead of thionyl chloride is used to modify o-CNTs to prepare CA-CNTs. It is found that CA has been associated with the surface of o-CNTs by esterification. Thus the oxygen groups, especially the carboxyls, on the surface of CNTs have been enriched and they are 7%(wt) of total mass. At the same time, due to the modification by CA, the intertwining of CNTs has been further eased, and their surface electronegativity also reduces, which is conducives to increasing their hydrophilic property. When the ratio of CA to o-CNTs is 7:1, Zeta potential of the CA-CNTs is minimal, about-42.6 mV. So after CA modification, the reactivity of o-CNTs has been enhanced, which means it is beneficial to following reactions.In addition, in this thesis, the CTS/CA-CNTs are prepared through covalent bond and crosslink function. The results show that CTS is associated with the surface of CA-CNTs through amide bonds. And the phase structure of CA-CNTs has changed. The carbon graphite peak becomes lower when the amount of CTS increases. As the ratio of CTS to CA-CNTs getting to 7:1, the carbon graphite peak mostly disappears and CTS has coated CA-CNTs to form membrane. The CTS is about 55%(wt) of the total mass. Meanwhile the CTS/CA-CNTs composites have good absorption ability of GOD, which means they have a potential application in the field of biosensor.Moreover, in this thesis, Fe2+-CTS/CA-CNTs composites are prepared by using CTS/CA-CNTs to absorb Fe2+ions. The results show that the CTS on the surface of CA-CNTs absorbs Fe2+by its-NH2 groups. The maximum content of Fe2+is 3.394%(wt). Fe2+-CTS/CA-CNTs composites are superparamagnetic, and their maximum Ms is 2.57 emu/g, much better than the magnetism of Gadonanotube, indicating that they have a potential application in the field of MRI.