The Synthesis Of The Luminescent Silica Nanoparticle And Its Biological Application

As a newly developed nano-material, silica nanoparticles attracted the researchers'focus on their diversified application in biological research. Among the diverse research studies that use dye-doped silica nanoparticles, ultrasensitive bioanalysis and cellular imaging have made the most remarkable progress and attracted the greatest interest. There are two general routes for the preparation of luminescent silica nanoparticles: St?ber method and reverse micro-emulsion strategy. Reverse micro-emulsion strategy is more preferable for its convenience to control the size and uniformity of the silica nanoparticles by changing the size of the reverse micelles.A series of luminescent silica nanoparticles have been fabricated through doping various hydrophilic luminophor and quantum dot inside the core of the nanoparticles. Hydrophobic dye doped silica nanoparticle could also be attained after making these molecules hydrophilic. These silica nanoparticles are extremely bright because of the encapsulation of thousands of fluorescent dye molecules inside the silica shell. Compared with the organic luminophor, the silica nanoparticles have greater fluorescent intensity and become more photostable. Bio-molecules such as DNA,antibody could be immobilized onto the nanoparticle surface in two patterns: physical adsorption or covalent linkage which endow the nanoparticles with diverse biological application.We have adopted the "one-step" method for introducing amine groups onto the nanoparticle surface, namely, by the hydrolysis of silane such as APS and TEOS at the same time. And another route named "two-step" method is also selected for fabricating silica nanoparticles. In this method the addition of APS is executed after the silica nanoparticle was formed. After comparing the fluorescent intensity, morphology, and monodispersity of the products of the two methods, we concluded that the"two-step"method is more preferable for the fabrication of the amine modified silica nanoparticles. Glutaraldehyde, EDC(1-ethyl-3-3(3- dimethylaminopropyl)carbodiimide hydrochloride)/NHS(N-hydroxy-succinimide)are used to couple silica nanoparticles with biomolecules. Glutaraldehyde links the nanoparticles and biomolecules through the Schiff base formed between the amine groups and other biomolecules. By deriving carboxyl groups from the amine groups on the surface, stable amide could be formed between the silica nanoparticles and the recognition molecules with the usage of the coupling agent EDC/NHS. We successfully attached mouse monoclonal antihuman CD71 antibody (McAb CD71) and transferrin onto the nanoparticle surface respectively through the latter method. And cell imaging results affirm that the luminescent nanopartilces successfully labeled the receptors in the fibroblast cells' membrane. This achievement is helpful for the luminescent silica nanoparticles' practical application.