Uniform silver-containing metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering （SERS） analyses. Nevertheless, the direct synthesis of such nanostruc...Uniform silver-containing metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering （SERS） analyses. Nevertheless, the direct synthesis of such nanostructures with strong and stable SERS signals remains extremely challenging. Here, we report a DNA-mediated approach for the direct synthesis of gold-silver nano-mushrooms with interior nanogaps. The SERS intensities of these nano-mushrooms were critically dependent on the area of the nanogap between the gold head and the silver cap. We found that the formation of nanogaps was finely tunable by controlling the surface density of 6-carboxy-X-rhodamine （ROX） labeled single-stranded DNA （ssDNA） on the gold nanoparticles. We obtained nano-mushrooms in high yield with a high SERS signal enhancement factor of -1.0×109, much higher than that for Au-Ag nanostructures without nanogaps. Measurements for single nano- mushrooms show that these structures have both sensitive and reproducible SERS signals.展开更多
In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopam...In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopamine （PDA） decorated Au nanoparticles （Au@PDA NPs） for ultrasensitive detection of carcinoembryonic antigen （CEA） has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully, especially cooperation with TiO2 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy （TEM） and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody （Ab2） of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody （Abl） on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL^-1 with a limit of detection of 0.35 pg mL^-1 （S/N = 3）.展开更多
基金We thank the National Basic Research Program of China （973 program） （Nos. 2013CB932802 and 2012CB932600）,Alexander von Humboldt Foundation, and the National Natural Science Foundation of China （Nos. 91127037 and 91123037） for financial support.
文摘Uniform silver-containing metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering （SERS） analyses. Nevertheless, the direct synthesis of such nanostructures with strong and stable SERS signals remains extremely challenging. Here, we report a DNA-mediated approach for the direct synthesis of gold-silver nano-mushrooms with interior nanogaps. The SERS intensities of these nano-mushrooms were critically dependent on the area of the nanogap between the gold head and the silver cap. We found that the formation of nanogaps was finely tunable by controlling the surface density of 6-carboxy-X-rhodamine （ROX） labeled single-stranded DNA （ssDNA） on the gold nanoparticles. We obtained nano-mushrooms in high yield with a high SERS signal enhancement factor of -1.0×109, much higher than that for Au-Ag nanostructures without nanogaps. Measurements for single nano- mushrooms show that these structures have both sensitive and reproducible SERS signals.
基金supported by the National Natural Science Foundation of China (21575022, 21535003)the National High Technology Research and Development Program of China (2015AA020502)+1 种基金the Open Research Fund of Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast Universitythe Fundamental Research Funds for the Central Universities (KYLX15-0127)
文摘In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopamine （PDA） decorated Au nanoparticles （Au@PDA NPs） for ultrasensitive detection of carcinoembryonic antigen （CEA） has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully, especially cooperation with TiO2 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy （TEM） and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody （Ab2） of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody （Abl） on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL^-1 with a limit of detection of 0.35 pg mL^-1 （S/N = 3）.
