Nanoparticles Self-assembly And The Applications In Electroanalysis

Since the late 1980s, investigation of nanomaterials has quickly become a new-emerging interdisciplinary science (Nano-Science). Nanomaterials consist of small particles with at least one dimension in the range of 1 nm to 100 nm. Because nano-dimension is in the range between atomic cluster and macroscopic object, this kind of materials show distinguished surface effect,small size effect,quantum size effect and quantum tunneling effect. These special effects result in many wonderful capabilities for their wide applications in optics,mechanics,magnetics,electrics,thermotics and chemistry.Preparation and self-assembly of nanomaterials has developed greatly in the past decades. But the main focus of nano-science to date has been either the exploit of the growth mechanism or the appraisal of their properties. Based on that, this paper contains the following contents:(1)Substrates with different wetting properties were prepared and on which self-assembly process of SiO2 nano-particles were observed. The cover glass is an important substrate for optical microscopic investigation, so the wetting property of the cover glass is very important for imaging, especially when the sample is a solution. The wettability of cover glass could be controlled by functionalizing with different organic ligands. The vaporation processes of the nano-particle solution are quite different on the surfaces with different wetting properties, and thus the resulting nano-particle assembly is different in structure and morphology. In the self-assembling process, knowledge of the movement mechanism of nano-particles in a small droplet is very limited. We attempted to learn the self-assembling mechanism of nanoparticles in the drying process of a small nanoparticle solution droplet placed on the surfaces with different wetabilities. By combining the Charge Coupled Device (CCD) and Differential Interference Contrast (DIC) microscopy, we carried out in-situ observations and recorded for the movement of nano-particles in a small droplet which is on different glass substrates. We found the movement trend of 200 nm SiO2 on glass substrates with different wetting property, which will help us to know more about the self-assembling process of nano-particles.(2) The electrocatalytic properties of Au nanoparticle films, prepared at liquid/liquid interfaces by the ethanol-mediated method, were investigated using NADH as probes. This study demonstrates the as-prepared Au nanofilms have a certain electrocatalytic activity to NADH, and found that Au particle size can influence the electrocatalytic properties of the resulting nanofilm, which can be explained by the increasement of catalytic sites.(3)Au nanoparticle multilayer films were fabricated by the layer-by-layer self-assembly, and after modified with horseradish peroxidase (HRP), their electrocatalytic activity was further studied. We observed that that the hydrophobicity and electrocatalytic activity of gold nanofilm will both become stronger with the increasement of the layer number of Au monolayers. When the layer number of gold nanofilm reaches 5 or 6, both the hydrophobicity and electrocatalytic activity of gold nanofilm are the maximum.