Preparation Of Aligned Carbon Nanotube Array Electrode And Its Application

In recent years, in order to understand the structure and the mechanism of electron transfer, as well as on the electrode surface simulations of biological electron transfer processes of proteins in vivo, the direct electrochemistry of redox protein based bio-sensors has been widespread concern and research. However, the electrical bio-active substances are often embedded in the active center of multi-polypeptide chain, while it is also easily and strongly adsorptable on the electrode surface to cause electrode passivation, and therefore the bare electrode surface is difficult to achieve the direct electron transfer.Carbon nanotubes for its unique mechanical, electrical and chemical properties, as well as a unique molecular structure of tubular and application value have become a research hotspot. As the easy-to surface functionalization of carbon nanotubes, a large surface area to promote the electron transfer reaction effect, can improve the sensitivity of bio-electrochemical sensor electrode; its good biocompatibility is conducive to maintaining the activity of immobilized organisms. In the introduction of other nanomaterials such as metal nano-particles, quantum dots, etc. After the bio-active substances can also further promote and sensor electrode electron transfer rate, more durable to maintain the activity of organisms, in order to develop more efficient, simple, durable, bio-electrochemical sensors provide a new way of thinking.In this paper, aligned carbon nanotube array of excellent physical, chemical, electro-catalytic properties and their good biological compatibility, combined with nano-particles which have quantum effects and large surface area effect, prepared two kinds of different types of modificated aligned carbon nanotube arrays electrode. Using chemical vapor deposition on quartz substrates were successfully prepared large area aligned carbon nanotube arrays, and it's made of aligned carbon nanotube array electrode. We used a variety of ways to fix the hemoglobin, glucose oxidase onto the array electrode interface and prepared bio-sensors which have higher sensitivity, lower detection limit and fast response speed advantages.Chapter One:PrefaceFirst, a systematic introduction to the discovery and application of carbon nanotubes, including carbon nanotubes of the structure and classification, properties, preparation methods, separation and purification as well as the application status. Aligned carbon nanotube arrays in biological and chemical sensors are mainly focuses on and reviewed.Chapter Two:Single temperature controlled aligned carbon nanotube arrays synthesizing by chemical vapor deposition method under atmospheric pressureIn this experiment, we used quartz as substrate, the metal phthalocyanine compounds of iron as raw material which can also produce carbon source and catalyst by its high-temperature pyrolysis, to prepare a large area carbon nanotube arrays with only a single temperature of the maximum temperature 890℃controlled under atmospheric pressure that will effectively reduce the test cost, simplify the experimental equipment. Through the improvement and optimization of process parameters, using chemical vapor deposition was achieved a large area, highly aligned carbon nanotube arrays.The even length of carbon nanotubes is about 10μm while its diameter about 50 - 70 nm. Experimental Investigation of the maximum furnace temperature, sublimation zone and the amount of iron phthalocyanine, carrier gas flow rate and the ratio of the preparation parameters and the substrate to the growth of aligned carbon nanotube arrays on the situation, the preparation and practical application of carbon nanotube research has significance.Chapter Three: Glucose oxidase/CdS nanoparticles/chitosan/Pt nanoparticles modified aligned carbon nanotube array electrode and its direct electrochemistryThis chapter we used the chemical vapor deposition method, iron phthalocyanine as raw materials in the quartz substrate to prepare a large area aligned carbon nanotube arrays.Spraying the surface of aligned carbon nanotube arrays by gold after treatment, and then with 40% HF solution makes the aligned carbon nanotube arrays and quartz film substrate separated and made the ACNTs to be working electrode. Field emission scanning electron micrographs showed that the growth of aligned carbon nanotube arrays prepared are high density, closely arranged, the length and diameter is close, orientation is good. We used two types of Pt and CdS nano-particles and glucose oxidase (GOD) to modify the aligned carbon nanotube arrays electrode as working electrode:first to electro-deposited platinum nano-particles (Ptnano) on the vertical carbon nanotube arrays; When the solution's pH value is greater than the pKa of chitosan, the glucose oxidase (GOD), CdS nanoparticles and chitosan (CS) mixed solution will electro-deposite onto ACNTs-Ptnano electrode surface. Experiments show that Pt nanoparticles can effectively increase the electrode surface area, improve the electrode electron transfer rate; CdS nano-particles can be effective in promoting glucose oxidase and vertical carbon nanotube arrays of direct electron transfer between electrodes to achieve a glucose oxidase Direct Electrochemistry of active site FAD/FADH2. This electrode-based glucose biosensor CS-GOD-CdS/ACNTs-Ptnano showed good sensing properties, with the linear range of detection of 0.4 mM - 21.2 mM, the lowest detection limit of 46.8μmol/L (S/N = 3), the apparent Michaelis-Menten constant of 11.86 mmol/L. After Electrode Saved 2 weeks, the sensor is still maintaining a good selectivity, repeatability and stability of electrochemical signals.Chapter Four: The directly electrochemical and electrocatalytic properties of hemoglobin on the diazotization salt modified aligned carbon nanotube array electrodeThis chapter through the electrochemical reduction of 4 - carboxyl-phenyl diazonium salt in the solution, we functional modificated the aligned carbon nanotube array electrode, and successfully made hemoglobin (Hb) molecules fixed in aligned carbon nanotube arrays electrode surface. Prepared aligned carbon nanotube array electrode has a good biological compatibility and electrical conductivity; the electrode surface carboxyl group provides more protein binding sites, making this function interface in the hemoglobin molecule can achieve the direct electron transfer. Using cyclic voltammetry and chronoamperometry we can research the direct electrochemistry and bio-electrocatalytic activity monitoring of Hb molecules. The results show that in 0.1mol/L pH = 7.0 in PBS solution, Hb-type amount of the potential of -0.312 V (vs. Ag / AgCl), heterogeneous electron transfer rate constant of 0.95±0.05 cm/s. The electrode have a good electro-catalytic reduction reactions to H2O2, its apparent Michaelis-Menten constant Kmapp is 0.15 mmol/L.