Preparation Of ZnO Nanorod Arrays And Effect Of Their Surface Wettability On Protein Adsorption

In recent years, inorganic nanomaterials have been widely used in versatile biomedical fields due to their unique physical and chemical properties. However, it is still lack of an in-depth understanding of the interaction mechanism between protein molecules and inorganic nanomatierals. And effective controlling of protein adsorption and desorption is difficult. All these things greatly restricted the practical process of nanomaterials biolabel system to a large extent. The surface wettability of inorganic nanomaterials has a significantly influence on the protein adsorption process. Although many reports referred in this regard, the conclusions are contrary. The reason is that most of these efforts used different materials with different wettbability to study the problems of protein absorption, ignoring the effects of materials composition. ZnO is an important photosensitive semiconductor. Its surface wettability can be reversibly switched between hydrophobic and hydrophilic by alternation of UV irradiation and dark storage. Therefore, this dissertation made ZnO nanoarrays as the main object. We studied systematically the influence of ZnO nanorods surface wettability on protein adsorption. The details are as follows:1. One-dimensional ZnO nanorod arrays were prepared via two-step processes. Seeds were first prepared by two methods: one was pull film method or another was radio frequency magnetron sputtering deposition. Then a simple low-temperature hydrothermal procedure was applied to obtain ZnO nanorod arrays. The morphology of arrays was characterized by SEM and XRD. In order to obtain ZnO nanorod arrays with different wettability from hydrophobic to superhydrophobic, the height of arrays was controlled by tuning the growth time or through the second growth method. UV illumination was used to reverse the surface wettability of arrays into hydrophility, or even superhydrophility.2. The adsorption behaviors of the protein were studied on condition of tuning the surface wettability of ZnO nanorod arrays. Bioconjugation of BSA on ZnO nanorods were confirmed by infrared spectra (FTIR) observations and energy dispersive analysis of X-rays (EDAX) studies. The adsorption quantities of BSA on the surface of nanorod arrays were determined by Coomassie brilliant blue G-250 dye-binding method. The results showed that adsorbed proteins were more on the hydrophilic surface than on the hydrophobic surface. In addition, ultraviolet light-emitting of ZnO array was enhanced after conjugating the proteins.