Preparation Of New Type Of Nanomaterials And Their Applications In Detecting Cytochrome C

Since the 1990s, nanotechnology has won the sustainable development. Nanometer materials have attracted much attention due to their peculiar physical and chemical properties and wide application prospects. New nanometer materials'combining with fluorescence analysis technology and photoelectric technology, has introduced more effective detection means into the field of analysis. Cytochrome c is one of the important information materials of cell apoptosis, developing simple and rapid detection method of cytochrome c is of great significance for clinical detection and biological research.This thesis will focus on realizing the rapid detection of cytochrome c by combination of nano technology with fluorescence analysis technology and photoelectrochemical analysis technology. We carry out the study in the following three aspects:(1) CdS/ZnIn2S4/TiO2 3D-heterostructures and their photoelectrochemical properties. Taking TiO2 nanotube arrays as the base material, the three-dimensional (3D) CdS/ZnIn2S4/TiO2 is prepared by co-use of a simple hydrothermal method and successive ionic layer adsorption and reaction (SILAR) techniques. The described synthesis approach offers a powerful technique for designing 3D heterostructure systems. Under AM1.5G illumination, the 3D CdS/ZnIn2S4/TiO2 sample generates a photocurrent density of 4.3 mA/cm2, with a photoconversion efficiency of 2%. Samples are tested for their ability to photocatalytically degrade target agents; noteworthy is that after 90 min illumination 100% of 2, 4-dichlorophenoxyacetic acid (2,4-D) is removed. While for ZnIn2S4/Ti02 and TiO2, only 72.3% and 39.1% of 2,4-D was removed, respectively. Stability experiment indicates good chemical stability of the material. In addition, we discuss the mechanism of photocatalytic degradation of CdS/ZnIn2S4/TiO2 for in detail.(2) A label free photoelectrochemical sensor for detecting cytochrome c based on Au/CdS/ZnIn2S4/TiO2 composite electrode materials. To obtain the highly electroactive Au/CdS/ZnIn2S4/TiO2 nanocomposite electrode, Au nanoparticles are deposited onto the surface of CdS/ZnIn2S4/TiO2 composite electrode through constant potential electrochemical deposition method and the electrode is used as the light electrode. Thiol modified aptamer, which can specifically bind to cytochrome c, acts as the probe, thus a label free photoelectrochemical aptasensor is builed to realize the quantitative detection of cytochrome c. Detection principle:the concentration of cytochrome c is determined by direct monitoring the change of photocurrent caused by the combination of aptamer and cytochrome c. In this method, combination of adaptmer with high specific recognition performance and high sensitive electrochemical detection technology brings the sensing system high selectivity and relatively low detection limit (1.0 pM). In addition, the experimental data shows that the sensor also has good reproducibility and stability.(3) A novel ultrasensitive sensing system for rapid fluorescence detection of cytochrome c was proposed by combining aptamer-based bioassay with VS2 nanosheets. Cytochrome c itself cannot be directly measured through fluorescence technology because it does not have fluorescent. So we developed an indirect fluorescence method for determination of cytochrome c in this study.VS2 nanosheets with high fluorescence quenching ability were synthesized by the all-in-solution route. Cytochrome c-binding aptamer was tagged with the fluorescent dye carboxy fluorescein, acting as the probe. VS2 nanosheets can adsorb the probe and quench its fluorescence efficiently. However, the fluorescence of the probe was retained when it was incubated with cytochrome c and then mixed with VS2 nanosheets solution. Due to the high specific properties of adaptmer used, the proposed sensing system shows high selectivity and sensitivity, giving a linear range of 0.75 nM to 50?M, and a limit of detection of 0.5 nM.