Aqueous Preparation, Characterization And Property Investigation Of Novel Optical-Magnetic Bio-Nanomaterials

In recent years, the preparation, characterization and biomedical applications of magnetic, fluorescent and magnetic fluorescent hybrid nanoparticles have attracted much attention. The controlled synthesis of nanomaterials is the basis for their property regulation and applications. Therefore, it is very important to establish and improve the methods to prepare well dispersed and stable nanomaterials with uniform size and morphology. Currently, organic phase synthesis method, micro-emulsion method, Stober method and some other methods have been established to prepare prepare fluorescent, magnetic and fluorescent magnetic nanomaterials, but the preparation or purification procedure of some methods are complex or time consuming, and the reactants are either expensive or toxic in some other methods, which are unfavorable for large-scale preparation. So, it will be of great significance to establish new synthesis methods to prepare stable, size and shape controlled nanomaterials by simple preparation and purification procedure with cheap and nontoxic or relative safe reactants.Based on the above reasons, this dissertation focused on the establishment of novel, simple and inexpensive synthetic route to prepare excellent magnetic, fluorescent and fluorescent magnetic nanoparticles. The major innovations of this work are as follow:(1) The effects of citric acid concentration and pH value on the saturation magnetization (Ms), crystallization and dispersion behavior of iron oxide nanoparticles were investigated systematically, and stable dispersion of superparamagnetic iron oxide nanoparticles under physiological pH has been prepared.(2) Iron oxide nanoparticles and rhodamine B were combined by the hydrolysis of silane in the mixture of water and ethanol for the first time, a new multifunctional nanomaterial which possesses optical and magnetic properties simultaneously was prepared and characterized.(3) A new aqueous method which can combine hydrophobic fluorescent dye and iron oxide nanoparticles through hydrophobic interaction was established for the first time, this method is simple and the prepared particles have no dye leakage.(4) A new method for preparing fluorescent magnetic nanoparticles through complexing effect by using silane,alumina salt and morin as raw materials was established. This method is economic and the problem of dye molecules leakage from the silica matrix was solved.(5) Multi-functional silica nanoparticles embedded with CdTe and iron oxide nanoparticles were prepared in the mixture of water and alcohol.(6) A new method for preparing fluorescent silica nanoparticles through the complexing effect between morin and aluminum ions by using tetraethylorthosilicate,alumina salt and Morin as raw materials was established, and the problem of Morin leakage was solved.This dissertation consists of seven chapters:Chapter 1:This chapter reviewes the main property and characterization methods of nanomaterials, especially for the preparation and biomedical applications of magnetic, fluorescent and magnetic fluorescent hybrid nanoparticles.Chapter 2:Iron oxide nanoparticles was prepared by co-precipitation method using the salts of Fe2+ and Fe3+ as reagent, NH3H2O and citric acid as precipitation agent and dispersion agent, respectively. The effect of citric acid concentration and pH on the Ms value, crystallization and dispersion behavior of iron oxide nanoparticles were investigated systematically. Stable dispersion of superparamagnetic iron oxide nanoparticles under physiological pH has been prepared.Chapter 3:Silica nanospheres doped with Rhodamine B and iron oxide nanoparticles were prepared in the mixed of alcohol and water, and characterized by a series of method. The results indicates the product is nanometer in size, the Ms value is 10 emug-1, their excitation and emission wavelength is 520 nm and 568 nm, respectively. These results proved the prepared nanoparticles possessed fluorescent and magnetic properties simultaneously.Chapter 4:iron oxide nanoparticles were coated with hydrophobic silica shell doped with Rhodamine 6G through the hydrolysis of hexadecyltrimethoxysilane and tetraethylorthosilicate (TEOS), a hydrophilic silica shell was then coated on the particles surface by the hydrolysis of TEOS. The results showes that the prepared nanomaterials have good optical and magnetic properties, the fluorescence intensity of the particles did not change for 6 days which indicated their fluorescent properties were stable. This is very important for improving the preparation methods of fluorescent magnetic nanomaterials.Chapter 5:A silica shell was coated on the surface of iron oxide nanoparticles prepared by co-precipitation method at first. Then, a layer of alumina was coated on the particles surface, and Morin was added finally, so a new type of fluorescent magnetic nanoparticles was prepared because Morin can form a fluorescent complex with the active Al ions on the particles surface. The characterization results show that the product is nanomaterial, and has good magnetic and optical properties. This experiment is important for establishing liquid method for preparing fluorescent magnetic nanoparticles with low cost and stable fluorescent properties.Chapter 6:Iron oxide nanoparticles were first coated with silica, and then modified with amino groups, the added CdTe quantum dots were assembled on the particles surface through the amino group, and the particles were covered with a layer of silica finally. Characterization results show that the prepared nanomaterials composed of quantum dots and iron oxide nanoparticles have good optical and magnetic properties, the product can be regulated by an external magnetic field and also can be detected by fluorescence microscopy. And compared with the existing methods, this method requires small amount of organic solvent, and the preparation is relatively simple.Chapter 7:A new type of fluorescent silica nanoparticles was prepared by using alumina nanoparticles complexed with Morin as fluorescent core. Characterization results show that the optical properties of these fluorescent nanoparticles are stable and have no dye leakage. The method is very useful for establishing a simple, low-cost liquid method for preparing fluorescent silica nanoparticles.