Synthesis Of Fluorescent Encoding Nanoparticles And Their Application In Biosensisng Based On SERS And Carbon Nanodots

As a kind of novel fluorescent carbonaceous materials, carbon dots have a great potential in fluorescence imaging, inorganic ion detection and optical trapping due to the low toxicity, strong and stable fluorescence emission. On the other hand, optically encoded fluorescent nanoparticles have attracted a board interest in molecular biology, cell biology, cell imaging, medical diagnostics, high-throughput drug screening, combinatorial chemical synthesis and other related areas.In this paper, metal nanoparticles were used as the SERS substrate and SiO2 spheres were used as the carrier. SERS and fluorescence encoded nanoparticles were acquired by electrostatically assembling carbon quantum dots and CdSe/ZnS quantum dots onto the SiO2 spheres layer by layer via polyelectrolytes and coupling agents. The optical properties of the obtained nanoparticles were carefully investigated. After successful fabrication of the optically encoded nanoparticles, DNA detection was performed to examine their potential applications in bioanalysis.In the experiments, a rapid, simple and efficient pyrolysis method was employed to synthesize carbon quantum dots with a blue emission. The structure and fluorescence properties were characterized through dynamic light scattering and fluorescence spectrometer. The influence of metal nanoparticles on the fluorescence properties was also analyzed in this step. Afterwards, Raman reporter labeled Au@Ag core-shell nanorods were used as the SERS signal generator, and they were wrapped by a silica shell to improve the stability. Then, carbon quantum dots and CdSe/ZnS quantum dots were assembled onto the silica shell to obtain the SERS-fluorescence dual mode nanoparticles. Joint spectral encoding using both SERS and fluorescence signals can greatly enhance the optical encoding capacity. Finally, to investigate the potential applications of the nanoparticles in biomolecule detection, cDNA was modified onto the nanoparticles and target DNA was detected through complementary base pairing. The experimental results confirmed that the fabricated nanoparticles are applicable in DNA detection.