Research On Sensing Characterstics Of Carbon Nanotube Functionalized By Biological Moleculars

Carbon nanotubes (CNTs) have become a focus of physical, chemical, material and even biological fields, due to their unique electronic and mechanical properties since their discovery in 1991 by Iijima. Due to their unique one-dimenoion structures, CNTs have excellent electrochemical properties that are useful for electrochemical studies, analytical application, catalysis and sensors, which provide a wider prospect.With the development of research work,nanomaterials are used widely as a new materials for electrodes modified by chemical methods and applied as biosensor or catalysis carrier.Used as modified electrodes by chemical method or the materials of sensors, CNTs not only have many nanomaterials'properties, but also have the large specific surface area, the high active surface, the many functional groups on the surface and the good bio-affinity. With the increasing of bioactive molecules immobilized on carbon nanotube, the response signal, reproducibility, detection limit and sensitivity of the modified electrodes also highly enhanced. These characteristics of carbon nanotube for the improving the performance of biosensor, biomedicine and biocatalysis have great significance. For the application of carbon nanotube on the biochemistry and the biological electroanalytical chemistry, CNTs must have the biospecific interaction with biomolecules, especially, the recognition of biomolecules. Thus, the CNTs are functionalized by the biomolecules to posses a good bio-affinity and the recognition function.This paper presents a research about carbon nanotubes functionalized by biomolecules, such as enzyme, protein, amino acid , peptide, deoxyribonucleic acid and antigen/antibody at home and abroad. Covalent functionalization of carbon nanotubes (CNTs) with DNA has been successfully achieved via forming covalent amide bonds between carboxyl groups of the nanotubes and amino groups at the ends of the DNA oligonucleotides. The morphology and the structure of CNTs covalently functionalized by DNA were examined by FT-IR spectra, AFM and field emission scanning electron microscope (FESEM). Electrochemical characteristics of the DNA functionalized CNTs and the interaction between DNA and ART (Artemisinin) has been investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS). The results showed that DNA retaining its bioactivity is covalently immobilized on the surfaces of CNTs and still has the ability to interact with other biomolecules. ART can be detected obviously by the preparation of DNA covalently functionalized CNTs electrodes (DNA/MWNTs).The interactions of HRP/Th immobilized on the HRP/Th/MWNTs electrodes with H2O2 were investigated by means of electrochemistry. The electrochemical behavior of H2O2 on the HRP/Th /MWNTs enzyme electrodes was investigated in detail. The scan rate and the concentration of H2O2 were studied for their effect on the electrochemical performance of H2O2 on the enzyme electrodes. The results show that the oxidational currents of enzyme reacted with H2O2 at HRP/Th/MWNTs electrode had linear relationship with scan rate from 50～400mV/s, as expected for an absorption control process. It can be found that the peak current of H2O2 increases with the increasing of concentration of H2O2. The foundation of HRP/Th/MWNTs electrodes was applied to the study on the interactions of HRP with H2O2 which was used as the sensor and biocatalysis was established.