Carbon nanodots (C-Dots) have attracted much attention in recent years due to their low cost, ready scalability, excellent chemical stability, biocompatibility and multicolor luminescence. Here, we report a facile strategy for producing highly luminescent, surface-different nitrogen-doped carbon dots (C-Dots) by using different ionic liquids (ILs). Intriguingly, the surface-different C-Dots show different selectivity for Cu2+ and Fe3+. To the best of our knowledge, this is the first example which shows that ILs are excellent precursors for producing luminescent nanomaterial used for detection of different metal ions. The resultant nitrogen-doped C-Dots are highly photoluminescent and can be used for multicolor bioimaging. Most notable, by taking different ILs as precursors, we obtain surface-different C-Dots, which can be directly used for selective detection of Cu2+ and Fe3+ without any modification. These C-Dots based sensors exhibit high sensitivity and selectivity and the sensing process can be easily accomplished with one-step rapid operation. More importantly, compared with other method using QDs, organic dyes and organic solvent, this strategy is much more eco-friendly. This work may offer a new approach for developing low cost and sensitive C-Dots-based sensors for biological and environmental applications. 相似文献
A novel nanohybrid ratiometric fluorescence probe comprised of carbon dots (C-dots) and hydrophilic CdSe@ZnS quantum dots (QDs) has been developed by simply mixing the blue-emission C-dots with red-emission carboxylmethyldithiocarbamate modified CdSe@ZnS QDs (GDTC-QDs). The nanohybrid ratiometric fluorescence probe exhibits dual emissions at 436 nm and 629 nm under a single excitation wavelength. Due to the strong chelating ability of GDTC on the surface of QDs to mercuric ion (Hg2+), the fluorescence of the GDTC-QDs in the nanohybrid system could be selectively quenched in the presence of Hg2+ while the fluorescence of the C-dots remained constant, resulting in an obviously distinguishable fluorescence color evolution (from red to blue) of the nanohybrid system. The detection limit of this method was found to be as low as 0.1 μM. Furthermore, the recovery result for Hg2+ in real samples including tap water and lake water by this method was satisfying, suggesting its potential application for Hg2+ sensing. 相似文献
Under the public spotlight, uranyl (UO22+) ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment. Herein, we present a simple and effective ratiometric fluorescence imaging method for the visualizing and quantitative detection UO22+ ions by cellphone-based optical platform. The sensing solution was prepared by mixing label-free red carbon dots (r-CDs) and blue carbon dots (b-CDs) together with a fixed photoluminescence intensity ratio of 4:1. When UO22+ ions were added, the fluorescence of r-CDs can be selectively quenched, while the fluorescence of b-CDs remains stable without spectral changes. With the gradually increase the amounts of UO22+ ions, the different response of dual-color CDs resulted in a signification color evolution from deep red to dark purple under the ultraviolet (UV) light illumination. Then, a cellphone-based optical platform was constructed for directly imaging the color change of the samples, and the built-in Colorpicker APP quickly output the red, green and blue (RGB) channel values of these images within one second. Interesting, there was a linear relationship between the ratio of red and blue (R/B) channel values and UO22+ ions concentration from 0 μmol/L to 30.0 μmol/L (R2 = 0.92804) with the detection limit of ∼8.15 μmol/L (signal-to-noise ratio of 3). In addition, the optical platform has also been applied to the quantification of UO22+ ions in tap water and river water sample. With the advantage of low-cost, portable, easy to operation, we anticipate that this method would greatly improve the accessibility of UO22+ ions detection even in resource-limited areas. 相似文献
Under the public spotlight, uranyl (UO22+) ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment. Herein, we present a simple and effective ratiometric fluorescence imaging method for the visualizing and quantitative detection UO22+ ions by cellphone-based optical platform. The sensing solution was prepared by mixing label-free red carbon dots (r-CDs) and blue carbon dots (b-CDs) together with a fixed photoluminescence intensity ratio of 4:1. When UO22+ ions were added, the fluorescence of r-CDs can be selectively quenched, while the fluorescence of b-CDs remains stable without spectral changes. With the gradually increase the amounts of UO22+ ions, the different response of dual-color CDs resulted in a signification color evolution from deep red to dark purple under the ultraviolet (UV) light illumination. Then, a cellphone-based optical platform was constructed for directly imaging the color change of the samples, and the built-in Colorpicker APP quickly output the red, green and blue (RGB) channel values of these images within one second. Interesting, there was a linear relationship between the ratio of red and blue (R/B) channel values and UO22+ ions concentration from 0 μmol/L to 30.0 μmol/L (R2 = 0.92804) with the detection limit of ~8.15 μmol/L (signal-to-noise ratio of 3). In addition, the optical platform has also been applied to the quantification of UO22+ ions in tap water and river water sample. With the advantage of low-cost, portable, easy to operation, we anticipate that this method would greatly improve the accessibility of UO22+ ions detection even in resource-limited areas. 相似文献
In this study, we synthesized simple, cheap, and stable nitrogen (N)-doped carbon quantum dots (N-CQDs) from Moringa oleifera roots. The N-CQDs exhibited an intense blue fluorescence and a quantum yield (QY) of up to 43.4%. When excited at 350 nm, the highest generated wavelength was observed at 445 nm. These N-CQDs were then successfully used to detect sulcotrione (limit of detection = 2 μg/mL); the method was reliable and exhibited good feasibility for measurements in real samples. When the N-CQDs concentration was 11.0 μL/mL, inhibitory rates against the pathogens, Corynespora cassiicola and Phytophtora nicotianae were 82.8% and 75.3%, respectively. To investigate N-CQDs safety for plant growth, different concentrations were investigated using sorghum seedlings, with N-CQDs exhibiting very low toxicity toward plant growth. Thus, these findings provide a basis for the development of N-CQDs as green pesticides. 相似文献
Heteroatom-doping carbon dots (CDs) have excellent fluorescence properties. In the paper, nitrogen (N) and phosphorus (P) co-doped CDs (N, P-CDs) were prepared through the hydrothermal method and characterized by TEM, PXRD, FT-IR, 13C NMR, XPS, UV–vis, and fluorescence spectra. The optical properties and drug (doxorubicin) - delivery performance of N, P-CDs were also studied. The results showed that the average size of N, P-CDs was 3.64 nm and the quantum yield was 30 %. The N, P-CDs had down- and up-conversion fluorescence properties, and the luminescence mechanism of the N, P-CDs was explained. The drug loading capacity of N, P-CDs was 39.11 %, and the drug delivery system (N, P-CDs-DOX) had low cytotoxicity, sustained release, and pH-targeted properties. The in vitro release of N, P-CDs-DOX belonged to the Weibull model and Fick diffusion, exhibiting the same release model and mechanism with free DOX. The N, P-CDs could deliver DOX successfully, which was demonstrated by the co-collocation of N, P-CDs and DOX in SH-SY5Y cells through single/two-photon imaging. N, P-CDs could potentially be used in drug-targeted delivery and cell imaging. 相似文献
A biomass nitrogen and sulfur codoped carbon dots (NS-Cdots) was prepared by a simple and clean hydrothermal method using leek, and was employed as efficient fluorescent probes for sensitive detection of organophosphorus pesticides (OPs). The leek-derived NS-Cdots emitted blue fluorescence, but was quenched by H2O2. Due to acetylcholinesterase/choline oxidase–based cascade enzymatic reaction that produces H2O2 and the inhibition effect of OPs on acetylcholinesterase activity, a NS-Cdots-based fluorescence “off-on” method to detect OPs-dichlorvos (DDVP) was developed. More sensitivity and wider linear detection range were achieved from 1.0 × 10−9 to 1.0 × 10−3 M (limit of detection = 5.0 × 10−10 M). This developed method was applied to the detection of DDVP in Chinese cabbage successfully. The average recoveries were in the range of 96.0~104.0% with a relative standard deviation of less than 3.3%. In addition, the NS-Cdots fluorescent probes were also employed successfully in multicolor imaging of living cells, manifesting that the NS-Cdots fluorescent probes have great application potential in agricultural and biomedical fields.
Nitrogen and sulfur co-doped carbon dots (NS-CDs) were synthesized by one-step solvothermal method using oleic acid as the medium, ʟ-cystine and citric acid monohydrate as precursors. Based on the “on-off-on” fluorescence quenching mode, a novel method was established for determination of both Fe3+ and ascorbic acid. The synthesized NS-CDs can be employed as fluorescence chemical sensors for the direct determination of free iron in the aqueous phase and indirect determination of the ascorbic acid contents of vitamin C tablets with linear ranges of 0–10 μM (n = 3) and 0–30 μM (n = 3), and detection limits of 36.6 and 102.5 nM, respectively. These results demonstrate that the proposed method exhibits good selectivity and linearity. 相似文献
CdSe/CdS quantum dots(QDs) functionalized by thiourea(TU) were synthesized and used as a fluorescent sensor for mercury ion detection.The TU-functionalized QDs were prepared by bonding TU via electrostatic interaction to the core/shell CdSe/CdS QDs after capping with thioglycolic acid(TGA).It was observed that the fluorescence of the functionalized QDs was quenched upon the addition of Hg~(2+).The quantitative detection of Hg~(2+) with this fluorescent sensor could be conducted based on the linear relationship between the extent of quenching and the concentration of Hg~(2+) added in the range of1-300 μg L~(-1).A detection limit of 0.56 μg L~(-1) was achieved.The sensor showed superior selectivity for Hg~(2+) and was successfully applied to the determination of mercury in environmental samples with satisfactory results. 相似文献
Direct,in situ selective detection of intracellular formaldehyde(FA)is of great significance for understanding its function in FA-related diseases.Herein,red carbon dots(RCD)are reported as label-free two-photon fluorescent nanoprobes for detecting and imaging of FA.Upon addition of FA,the-NH2 groups of RCD could quickly and specially react with aldehydes to form Schiff base and then the strong fluorescence of RCD with blue-shift emission is recovery due to the destruction of the hydrogen bond interaction between RCD and water.In addition,the nanoprobes exhibit outsta nding photo stability,rapid response(<1 min),high sensitivity(~9.9μmol/L)and excellent selectivity toward FA over other aldehyde group compounds.Notably,owing to the good cell-membrane permeability and biocompatibility,as well as the large two-photon absorption cross-section,the as-prepared RCD can be used as label-free nanoprobes for selectively detecting and imaging FA in living cells and zebrafishes through one-photon and two-photon excitation.Moreover,RCD could stain the tissue of zebrafishes at depths interval of up to 240μm under two-photon excitation.This research implied that RCD are promising tools for directly and in situ imaging FA in vivo,thus providing critical insights into FA-related pathophysiological processes. 相似文献
CdTe quantum dots (QDs) were synthesized in aqueous solution with 3-mercaptopropionic acid as the stabilizer. Chemically reduced
bovine serum albumin (BSA) was used to modify the surface of the QDs. Experimental results showed that the denatured BSA (dBSA)
could be effectively conjugated to the surface of CdTe QDs. Column chromatography was used to purify the conjugates and determine
the optimal ratio of dBSA to QDs. Further experimental results showed that the conjugation of QDs by dBSA efficiently improved
the photoluminescence quantum yield, the chemical stability of QDs and their stability against photobleaching. A facile and
sensitive method for determination of silver(I) ions was proposed based on the fluorescence quenching of the dBSA–QDs. Under
the optimal conditions, the relative fluorescence intensity decreased linearly with the concentration of the silver(I) ions
in the range 0.08–10.66 μM. The detection limit was 0.01 μM. This study provides a new method for the detection of metal cations.
Figure In this work, denatured BSA was used to modify the surface of CdTe QDs by a simple and rapid method. And the conjugates of
dBSA-QDs were purified by column of Sephadex G-100. After the purification of the conjugates, the sensitivity was greatly
increased as silver (I) ions probe. 相似文献
Carbon nanodots (CDs) with superior fluorescence performance were obtained by hydrothermal method using tomatoes as raw materials. When the ultraviolet absorption band of tartrazine and the fluorescence spectrum of CDs have complementary overlaps, the fluorescent internal filter effect (IFE) occurred. Furthermore, the degree of quenching of fluorescence intensity of CDs has an excellent linear correlation with tartrazine concentration. And based on this principle, a method for detecting tartrazine was established. As the decrease of fluorescence intensity, tartrazine can be measured in the linear range of 0.1 μM–40 μM. The detection limit is 39 nM, and the recovery rate is 90.7%~114.5%. The established protocol was also effectively employed to assay tartrazine in beverage samples, indicating that it has great potential for food color analysis. 相似文献