Sensitive Fluorescent Sensor For Detection Research Articles

Carboxyl-Rich Carbon Dots as Highly Selective and Sensitive Fluorescent Sensor for Detection of Fe3+ in Water and Lactoferrin.

As lactoferrin (LF) plays an essential role in physiological processes, the detection of LF has attracted increasing attention in the field of disease diagnosis. However, most current methods require expensive equipment, laborious pretreatment, and long processing time. In this work, carboxyl-rich carbon dots (COOH-CDs) were facilely prepared through a one-step, low-cost hydrothermal process with tartaric acid as the precursor. The COOH-CDs had abundant carboxyl on the surface and showed strong blue emission. Moreover, COOH-CDs were used as a fluorescent sensor toward Fe3+ and showed high selectivity for Fe3+ with the limit of detection (LoD) of 3.18 nM. Density functional theory (DFT) calculations were performed to reveal the mechanism of excellent performance for Fe3+ detection. Meanwhile, COOH-CDs showed no obvious effect on lactobacillus plantarum growth, which means that COOH-CDs have good biocompatibility. Due to the nontoxicity and excellent detection performance for Fe3+, COOH-CDs were employed as a fluorescent sensor toward LF and showed satisfying performance with an LoD of 0.776 µg/mL, which was better than those of the other methods.

Fe(Ⅲ)-Oxidized Graphitic Carbon Nitride Nanosheets as a Sensitive Fluorescent Sensor for Detection and Imaging of Fluoride Ions

Since excess fluoride ions may lead to a severe health hazard, it is imperative to design a facile and sensitive sensor to detect it in both environmental and biological systems. The reported methods are always subjected to some limits, hampering their practical application. Herein, a two-dimensional turn-on fluorescent sensor, Fe3+-integrated oxidized graphitic-phase carbon nitride nanosheets (Fe-g-CNO), was synthesized via a facile and green method for sensitive detection of fluoride ions. The interactions between the C-N/C = N moieties of oxidized graphitic-phase carbon nitride (g-CNO) and Fe3+ caused fluorescence quenching of g-CNO. Upon addition of F- ions, the fluorescence was recovered through the formation of complex of Fe3+ and F-. The limit of detection of the sensor was 1 × 10-6 M. Furthermore, this probe could be used as an imaging agent of fluoride ions in living cells and teeth for diagnosis of dental fluorosis. The work provides a safe and efficient platform for further environmental and biomedical uses.

One-pot synthesis of N-doped graphene quantum dots as highly sensitive fluorescent sensor for detection of mercury ions water solutions

A facile hydrothermal approach was taken to synthesize environmental-friendly and water-soluble fluorescence N-doped graphene quantum dots (N-GQDs) by using citric acid and ethylenediamine as the reactants. The photoluminescence properties of N-GQDs were investigated and applied to determine the trace of Hg2+ in aqueous solution. The fluorescence of N-GQDs was dramatically quenched after the addition of Hg2+. This is due to the efficient charge transfer and coordination interaction between N-GQDs and mercury ions. The N-GQDs base fluorescence sensor exhibit excellently selective and sensitive response to Hg2+. According to the standard curve analysis, a two-stage liner response to Hg2+ can be obtained in the concentration ranging from 1 nM to 1000 nM. The detection limits (LOD) were calculated as 0.45 and 67.3 nM, respectively, which could satisfy the requirements of Hg2+ detection in water. The fluorescence N-GQDs presented here provides a functional platform with low detection limit, excellent selectivity and high sensitivity.

A Salen-based covalent organic polymer as highly selective and sensitive fluorescent sensor for detection of Al3+, Fe3+ and Cu2+ ions

A novel covalent organic polymer (Salen-COP) based on Salen-type Schiff base was synthesized by one-pot protocol involving the self-condensation of 3-formyl-4-hydroxyphenylboronic acid and the subsequent aldehyde–amine condensation with benzene-1,2-diamine. The Salen-COP was characterized by 13C CP/MAS NMR, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and X-ray powder diffraction spectrometry analysis. The morphological features of Salen-COP were also analyzed using scanning electron microscopy. The Salen-COP exhibited the significant fluorescence enhancing for the sensing of Al3+, while the obtained polymer also exhibited the dramatic fluorescence quenching for the sensing of Fe3+ and Cu2+. The detection limits were calculated to be 0.248 µM for Salen-COP@Al3+, 0.545 µM for Salen-COP@Fe3+ and 0.140 µM for Salen-COP@Cu2+, respectively. Furthermore, the Salen-COP was founded to be a reversible chemosensor for Al3+, Fe3+ and Cu2+ ions, which provided a unique opportunity in the development of multi-response polymer-based sensors.

Synthesis and characterization of p-dimethylaminobenzaldehyde benzoylthiourea and study towards selective and sensitive fluorescent sensor for detection of iron (III) cation in aqueous solution

Benzoyl thiourea derivatives ligand backbones contain Oxygen (O), Nitrogen (N), and Suphur (S) donor atoms can react with transition metal ions and form stable metal complexes. A new ligand was synthesized by the reaction of benzoyl isothiocyanate with diethylenetriamine and characterized by using Elemental Analysis (EA), Infrared (IR) spectroscopy and proton Nuclear Magnetic Resonance (1H NMR) spectroscopy. The monofunctionalize ligand were synthesized using 1:1 condensation of p-dimethylaminobenzaldehyde with diethylenetriamine and confirmed by disappearance of carbonyl group, C=O at 1656 cm-1 with the appearance of peak C=N in the range 1633 - 1638 cm-1 in the IR spectrum. This monofunctionalize ligand was synthesis by using Schiff base technique. Benzoyl thiourea derivatives, HN are synthesis from the 1:1 condensation of benzoyl isothiocyanates with monofunctionalized ligand. HN ligand was verified by the presence of peaks v(N-H), v(C=O), v(C=N) v(C-N) and v(C=S) at 3317 - 3336 cm-1, 1612 -1660 cm-1, 1550 -1589 cm-1, 1234-1366 cm-1 and 709-767 cm-1 respectively while 1H NMR show peaks of alkane (CH2), benzene (Ar-H), CONH, CSNH at 3.75, 6.73 – 7.33, 8.19, and 8.25 respectively. The total percent composition of C, H, N, O, and S using Elemental Analysis for HN, C21H27N5OS found was 85.23%. For application, further study on selectivity and sensitivity of HN ligand was conducted on several metal ions. The fluorescent emission spectroscopy shown that HN is a selective fluorescent sensor for Fe3+ and Cu2+ ions but not for other metal ions such as Co2+, Ni2+, Mn2+, Cr3+ and Zn2+. However, HN ligand shows more sensitive towards Fe3+ ions than Cu2+ ions which provide rapid detection of Fe3+ ions at concentrations as low as 4.5 x 10-7 M than 2.9 x 10-6 M of Cu2+ ions. As conclusion, HN ligand was expected to be useful as efficient chemical sensor for detection of Fe3+ ion.

A Sugar‐Quinoline Fluorescent Chemosensor for Selective Detection of Hg2+ Ion in Natural Water.

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A sugar-quinoline fluorescent chemosensor for selective detection of Hg2+ ion in natural water

A selective and sensitive fluorescent sensor for detection of Hg2+ in natural water was achieved by incorporating the well-known fluorophore quinoline group and a water-soluble D-glucosamine group within one molecule.