Study On Carbon Nanotubes Signal Amplification And High Sensitive Biosensor Construction

This dissertation focuses on designing and fabricating novel biomimetic interface combining with functional carbon nanotubes (CNTs) for the immobilization of biomlecules. Transmission electro microscopy (TEM), Scanning electron microscopy (SEM), and electrochemical techniques are used to study the properties of the interface. We discussed their applications in bioanalysis. This research focus on the details as follow:1. Bienzyme bionanomultilayer electrode for glucose biosensing was constructed based on polyelectrolyte functional CNTs through layer-by-layer (LBL) assembly. Bionanomultilayer electrode was fabricated based on electrostatic interaction between carbon nanotubes and horseradish peroxidase (HRP) or sugar-lectin biospecific interaction between concanavalin A (ConA) and glucose oxidase (GOD) through LBL assembly. The developed bienzyme biosensor exhibited fast amperometric response for the determination of glucose. The linear response of the developed biosensor for the determination of glucose ranged from 2.0×10-6 to 1.7×10-4 mol L-1 with a detection limit of 2.5×10-7 mol L-1. The biosensor can be used to determine glucose in serum directly.2. A signal amplification probe was constructed based on functionalized CNTs labeled with HRP and HRP-secondary antibodies (HRP-Ab2).The enzyme was assembled onto CNTs using LBL assembly and sugar-lectin biospecific interaction. Greatly amplified sensitivity was achieved by loading a large number of enzymes througe LBL assembly.3. A sandwich-type amperometric immunosensor for carcinoembryonic antigen (CEA) was fabricated by using functionalized CNTs labeled with HRP and HRP-Ab2. The gold electrode was modified by monlayer cysteine on which carcinoembryonic antibody(Ab1) was immobilized. The developed sandwich-type amperometric immunosensor exhibited fast amperometric response for the determination of CEA. The response is linear in the range of 0.05 to 5 ng mL-1 and 5 to 200 ng mL-1, with a detection limit of 0.018 ng mL-1. The biosensor can be used in serum directly.