Shell Material To Silica Core-shell Nanomaterials Synthesis, Assembly And Application

Nanomaterials exhibit unique properties compared with traditional materials in the application of magnetic, optic, electricity and thermodynamic due to of their surface effect, quantum size, small size and quantum tunnel effect. Recently, more and more efforts have been focused on the design and synthesis of size-controlled core-shell materials. As a result of the existence of shell, core-shell nanoparticles have many advantages. For example, electric charge of the surface of nanoparticles can be changed, and the surface of nanoparticles can be functionalized. Moreover, we can combine different materials together and they show new properties.The synthesis of core-shell nanoparticles can combine different functions together, and also can emerge new characters. It generally includes four aspects: first, the bulk material in core-shell structures exhibit extraordinary features compared with the original elements. Second, we can adjust the surface properties of the nanoparticles in order to change the surface charge intensity and improve the functionality, biocompatibility, stability and dispersibility. Third, hollow nanoshell can be obtained through the core nanoparticles. Last, multi-functional nanoparticles are produced through composed of various materials. It has not only been widely used in the research of colloidal chemistry, but also has potential application in catalytic, biological, medicine, optic, electricity, magnetic, thematic and high-performance mechanical materials. Core-shell nanoparticles are often prepared through two steps: first, we synthesize the monodisperse particles as the core material and then the further cladding of shell is proceeded.There are many sorts of materials which can be composed of core-shell nanostructures. SiO₂ receives more and more attention because its preparation is easier and the shell thickness is adjustable. In this article, we synthesized different sorts of nanoparticles, which all choose SiO2 as shell. Then they are functionalized for the further research. Based on this, we develop two aspects of works: First, organic dye is widely used in analytical chemistry, especially as label molecule. But it has some disadvantages, such as photobleaching, which inhibits its application in biosensing. FITC-core shell nanoparticles are prepared and characterized by TEM, UV, Fluorescence and so on. We investigate that the nanoparticles possessed high stability, high fluorescence intensity and poor photobleaching. Then the surface of the nanoparticles is functionalized with amino group for further application in the covalent label in biomolecules.Second, a novel fluorescent nanoprobe for detection of superoxide anion radical (O₂^·-) was designed and synthesized by a simple self-assembly method based on 2-chloro-1, 3-dibenzothiazolinecyclohexene (DBZTC) and SiO₂@Ag core-shell nanoparticles. The silica shell of SiO2@ AgNPs increases the interparticle distance of DBZTC@Ag and enhances the fluorescence intensity of the DBZTC. The DBZTC@ SiO2@Ag nanocomposite shows 3.1-fold fluorescence intensity enhancement and lower detection limit (0.73 nM) for detecting O2??. The selectivity for detection O2?? is also greatly improved. Then we applied the nanoprobe to the imaging in cells and cell viability test, which expressed good biocompatibility.