Synthesis Of Semiconductor Nanomaterials And Its Application In Photoelectric Biosensor

Current analytical chemistry trends the innovation. The development of bioscience, environmental science and new material science has made new research subjects on analytical chemistry. For instance, biologically active substances including. DNA, proteins, drugs and environmental toxic substances were exclusively selected as research analytes. Analytical systems have been transferred from simple systems to complex systems. Analytical methods have trended forward biochemical methods involving enzymatic and immunochemical reactions. Considerable efforts have made during the last decades to improve conventional analytical methods in accuracy, sensitivity, selectivity, fastness and automation, and to develop new methodologies for industrial, environmental and biomedical processes. In recent years, highly selective and sensitive analytical methods such as immunoassay and biosensor have been received much attention. The development of a rapid, sensitive and selective method and the fabrication of a simple and cheap analytical device for the detection of biological molecular substances have been a long-standing goal.The aim of the present work is to develop novel electrogenerated chemiluminescence immunoassay and to design and fabricate electrochemical biosensors for the determination of biological molecule with sensitivity, selectivity and simplify. In this thesis, taking advantages of the unique properties of nanoparticles and the specificity of biological molecular recognition substances, such as enzyme, antigen/antibody, DNA, we have designed a series of electrochemical biosensors and developed a series of electrogenerated chemiluminescece immunoassay for the determination of hydrogen peroxide, glucose, phenol, IgG, digoxin, and DNA.The paper includes two parts:the first part is review; the second part is research report.The chapter one is the background and current progress of the study. We describe the concept and feature of nanomaterials. In this part, we also introduce some modification methods about aptamer and the nanotechnology. Finally, we introduce the sensor types, summarize the progress of photoelectrochemical sensor and raise our research content and purpose.The chapter two is the synthesis of six nanomaterials and their functionalizations. We build six3D nanomaterials that have high specific surface areas. T1O2nanotube is obtained by anodic oxidation. TiO2-CdS is obtained by absorption CdS particles. ZnO is synthesized under control temperature, with the mixed solution of Zn(NO3)2-6H2O and HMT, and ZnO nanorods has grown on the FTO surface. SiO2is obtained by electron-beam evaporator. By this method, we can see equally distributed nanorods on the substrate. After that, XRD and SEM represent the morphology features. These materials show large specific surface areas. Then, we make a HRP enzyme biosensor, utilizing HRP as a recognition molecule, H2O2as a target, and detect electron transfer from HRP-H2O2reaction.The chapter three is to build a new photoelectrochemical sensor that has strand hybridization and specific character from dye sensitized semiconductor. This method has a high sensitivity and well light stablility for detecting nucleic acid. First, we chose TiO2/FTO as electrode, and immobilized amino DNA ps2on the surface to adsorb dye. Through glutaraldehyde crosslink, ps2m.c will reach electrode surface, after that TET nucliec acid and ps2m.c nucleic acid are mixed on the electrode. We choose six dye to find which has the best response with TiO2nanomaterial. In the photocurrent data, Ru(bpy)2dppz2+has best photocurrent response. Because TET is tetrahedral structure that can increase photocurrent due to the large amount of the adsorption dye. So by adsrobing the Ru(bpy)2dppz2+which can embed in nucliec acid, the system will show a good optical signal with high sensitivity in well linear relation with target concentration. The sensor can give life science a potential strategy.The chapter four is a new label free photochemical biosensor based on G-quadruplex. We survey the photocurrent response of N-doped TiO2nanomaterial in K+. We select G-quadruplex as a recognition element and K+as target.By strong lights illumination to form hydroxyl group, amino DNA is immobilized on electrode surface. When there is K+in testing system, DNA will form G-quadruplex, which can recognize hemin molecule. Because hemin is electrophilic, the electron transfer route will be changed following the K+/hemin/G-quadruplex structure. The biosensor has a good response to K+in the presence of140mM Na+. The limit of detection is0.1μM. It is a effectivelly method to test K+in life entity.In the paper we prepare3D nano material as a stating point and get six materials by six methods. The morphologies and properties can be obtained by SEM and XRD. By dye sensitizing, we can increase the light absorption property of semiconductor. Three dimensional has a large surface area, so we select HRP, DNA(ps2m.c), aptamer(G-quadruplex) as analysis recognition elements and cyclic voltammetry, AC impedance, chronopotentiometry as the detection tecnologies to detect targets. The work not only give photoelectrochemical biosensor a new idea, but also show a potential analytical method for early diagnosis in clinical diseases.