A novel nanocomposite, silicon–carbon-based dots@dopamine (Si-CDs@DA) was prepared using (3-aminopropyl) triethoxysilane, glycerol, and dopamine as raw materials via a rapid microwave-assisted irradiation. This type of Si-CDs@DA exhibited ultrabright fluorescence emission (quantum yield of 12.4%) and could response to Ag+ selectively and sensitively. Moreover, the obtained Si-CDs@DA can be further applied in sensing intracellular Ag+ and cell imaging, because of its photostability, salt stability, and low cytotoxicity. This study provides a simple and efficient approach for preparing novel Ag+ fluorescent probes, which could expand the application of carbon nanomaterials in designing related biosensors.
Silicon-hybrid carbon dots (Si–CDs) was synthesized using rice husk as a raw material via a carbonization and acid-cutting method. The as-prepared Si–CDs could be well dispersed in water and exhibits unique blue photoluminescence emission. Furthermore, the Si–CDs notably distinguished between four groups of trivalent rare earth elements ions (REEs). The fluorescence mechanisms behind this were likely due to not only the different fluorescence quenching effects of the REEs, but also that the Si–CDs could transfer the absorbed energy to Tb3+, Eu3+ and Dy3+ ions to enhance their characteristic fluorescence emission intensity. The fluorescence intensity ratio (F546/FSi–CD) exhibited a good linear relationship in the Tb3+ concentration range from 1 to 12 μM with a detection limit of about 3.24 nM, and performed satisfactorily in real water samples. In the meantime, a linear relationship was also achieved at wavelengths of 616 nm or 575 nm, correlated with the fluorescence intensity and concentrations of Eu3+ or Dy3+ in the ranges of 1–16 μM or 4–30 μM, and the detection limit achieved was 0.15 μM or 2.43 μM, respectively. Therefore, the as-prepared Si–CDs could be a potential material for the qualitative and quantitative fluorescent probing of REEs.
Hao Guo,Liping Peng,Ning Wu,Bingqing Liu,Mingyue Wang,Yuan Chen,Zhilan Pan,Yinsheng Liu,Wu Yang
A blue fluorescent Si/CDs is successfully synthesized via a conventional solvothermal method , which can serve as a sensitive fluorescent sensor to detect Hg 2+ ions in water. The synthesized Si/CDs material exhibits excellent optical properties , high chemical and structural stability in an aqueous solution. Under natural light, the mixture is a colorless suspension while under ultraviolet light, it can emit bright blue fluorescence and the maximum excitation and emission wavelengths are 377 and 464 nm, respectively. Particularly, Hg 2+ can lead to nearly complete fluorescence quenching of the material suspension and the emission intensity of the constructed fluorescent sensing system linearly decreases with increasing Hg 2+ concentration in the range of 0–200 μM with a detection limit of 26.7 nM (S/N = 3). The proposed method has been successfully applied in detection of Hg 2+ content in environmental and drinking water samples. In addition, the test paper strips based on fluorescent Si/CDs are also prepared by an immersion method for rapid and quantitative detection of Hg 2+ in water environment through a visual mode.
Organosilane-functionalized carbon dots (SiCDs) immobilized silica composite nanoparticles (Fe 3 O 4 @SiO 2 @mSiO 2 -SiCDs) with dually emissive properties have been prepared by a modified sol-gel method. Such Fe 3 O 4 @SiO 2 @mSiO 2 -SiCDs nanoparticles solution exhibits blue light emission with a maximum wavelength of 470 nm at lower concentrations, and red-shifts to yellow-green light emission with maximum wavelength of 565 nm at higher concentrations, which is different with traditional carbon dots composite materials displaying strong emission only in the blue-light region. The SiCDs are immobilized in the outer mesoporous silica layer by covalent bonds via proper blending ration, which enables the nanoparticles solution to possess excellent fluorescence stability. The Fe 3 O 4 @SiO 2 @mSiO 2 -SiCDs nanoparticles show good stability, high surface area (483.19 m 2 /g), high saturation magnetization (22.1 emu/g) and low remanence (0.217 emu/g). When the concentration of nanoparticles solution is increased, the distance between the nanoparticles decreases and exhibits the concentration-mediated scattering phenomena, which result in the red-shift of fluorescent peaks. The specific structure of the Fe 3 O 4 @SiO 2 @mSiO 2 -SiCDs nanoparticles and the concentration-mediated scattering phenomena play key roles in the red-shift appearing.
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