Synthesis And Application In Biological Detection Of Fluorescent Silica Nanoparticles

HR-TEM, AFM, Zeta potential, XPS,IR, EDX,Fluorescent spectrum, UV, fluorescent Microscope, Confocal Fluorescent Microscope and fluorescent ELISA were used to analyze the synthesis, modification and application of fluorescent silica nanoparticles (FSNPs). The synthesis methods of fluorescent silica nanoparticles (FSNPs) were optimized also. The applications of FSNPs were focused on bioassay, such as protein lable, food assay and connecting with little drug molecules in this paper.Stability of microemulsion, water-oil ratio (W₀), dye amount in silica particle, reaction time are key factors in synthesizing FSNPs. The results obtained showed as follows: 1. The diameter distribution of FSNPs was even and fluorescence was better when microemulsion had been stablized for 24 h. 2. The more the water-oil ratio (W₀) was, the less size of the particles could be obtained. When W₀ was 10:1, the size was 50nm and when W₀ was 40:1, the particles were too small to separate each other. 3. FSNPs were formed after TEOS and NH₃·H₂O were added into microemulsion, their size reached 50nm after 12h reaction, it was useless to prolong the reaction time when reaction 24h. 4. The optimum concentration of FSNPs is around 1.0mg /ml, and the optimum dye amount is 2μmol for 50nm particles.The optimum condition of amino group modification on FSNPs was achieved. 1. APTS (APTS:TEOS=1:1) was added into microemulsion after 12h reaction of TEOS, which could produce good surface modification on particles without bigger size. 2. FSNPs tended to aggregate when they coverd by amino groups for the formation of hydrogen bondings among amino groups and lower absolute value of zeta potential, but the aggregation was not severe when pH value was 7.5, or when particles were connecting with antibodies. 3. The successful link between particles and carnosic acid demonstrated that fluorescent silica nanoparticles could act as assistant material in drug metabolism.Glutaraldehyde and sodium periodate were employed to link antibody and NH₂- FSNPs respectively. The bioassay results showed the specificity and stability was better when linking with sodium periodate method. The NH₂-FSNPs showed good specificity and stability When they were used to recognize mesenchymall stem cells (MSCs) through CD44 on cell membrane or an intracellular protein, focal adhesion kinase (FAK). The fluoresccent light emitted from NH₂-FSNPs was strong and it was easy to observe the target cells by microscopy. The detection of meat source with FSNPs was also founded. The results showed that the method was stable, specific and sensitive, samples were easily prepared also comparing with PCR methods.