SciCombinator

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Journal: Journal of fluorescence

27

The first fluorescent sensor for HF2 (-) anion, N(1), N(3)-di(naphthalene-1-yl)isophthalamide (L) has been derived from α-Napthylamine and isopthaloyl chloride. In 1:1 (v/v) DMSO:H2O, L exhibits high selectivity towards HF2 (-) anion with a 4-fold enhancement in fluorescent intensity. Very little enhancement in fluorescence intensity is observed for F(-), Cl(-), Br(-), I(-), SCN(-), PO4 (3-), SO4 (2-), and CH3COO(-) anions. The stoichiometry interaction between L and HF2 (-) is found to be 1:1 from fluorescence and UV/Visible spectral data. DFT calculation shows that binding between HF2 (-) and L is 1:1 and increases the relative planarity between the two naphthyl rings causing fluorescence enhancement. A shift of 0.080 V in oxidation potential of L is observed on interaction with HF2 (-) by cyclic voltammetry and square wave voltammetry.

Concepts: Electron, Light, Hydrogen, Fluorescence spectroscopy, Electrochemistry, Atom, Ion, Squarewave voltammetry

27

As the hardware of FLIM technique becomes mature, the most important criterion for FLIM application is the correct interpretation of its data. In this research, first of all, a more orthogonal phasor approach, called as Modified Phasor Approach (MPA), is put forward. It is a way to calculate the lifetime of the complex fluorescent process, and a rule to measure how much the fluorescence process deviates from single exponential decay. Secondly, MPA is used to analysis the time-resolved fluorescence processes of the transfected CHO-K1 Cell lines expressing adenosine receptor A1R tagged by CYP and YFP, measured in the channel of the acceptor. The image of the fluorescence lifetime and the multiplication of the fluorescence lifetime and deviation from single exponential decay reveal the details of the Homo-FRET. In one word, MPA provides the physical meaning in its whole modified phasor space, and broadens the way for the application of the fluorescence lifetime imaging.

Concepts: Fluorescence, Measurement, Radioactive decay, Computer program, Real number, Exponential function, English Channel, Ruler

27

Fluorescent PET (Photoinduced Electron Transfer) has been of particular growth in recent times. A novel PET based fluorescent sensor using unmodified CdSe quantum dots (QDs) has been developed for the trace determination of Nimesulide (NIM). The sensor is based on the selective fluorescence quenching of quantum dots by NIM in presence of other NSAIDs and is found that intensity of quenching is linearly related to NIM concentration in the range 8.2 × 10(-7) - 4.01 × 10(-5) M. The mechanism of interaction is discussed. Finally, the potential application of the proposed method for the trace determination of NIM in pharmaceutical formulation is demonstrated.

Concepts: Fluorescence, Electron, Spectroscopy, Pharmacology, Ultraviolet, Light, Non-steroidal anti-inflammatory drug, Quenching

25

Based on resonance energy transfer (FRET) from dansyl to rhodamine 101, a new fluorescent probe (compound 1) containing rhodamine 101 and a dansyl unit was synthesized for detecting Hg(2+) through ratiometric sensing in DMSO aqueous solutions. This probe shows a fast, reversible and selective response toward Hg(2+) in a wide pH range. Hg(2+) induced ring-opening reactions of the spirolactam rhodamine moiety of 1, leading to the formation of fluorescent derivatives that can serve as the FRET acceptors. Very large stokes shift (220 nm) was observed in this case. About 97-fold increase in fluorescence intensity ratio was observed upon its binding with Hg(2+).

Concepts: Fluorescence, Spectroscopy, Light, Fluorescence spectroscopy, Chemistry, Solutions, Förster resonance energy transfer, Stokes shift

24

Competitive dye displacement titration has previously been used to characterize chitosan-DNA interactions using ethidium bromide. In this work, we aim to develop a fast and reliable method using SYBR Gold as a fluorescent probe to evaluate the binding affinity between ssRNA and chitosan. The interaction of chitosan with ssRNA was investigated as a function of temperature, molecular weight and degree of acetylation of chitosan, using competitive dye displacement titrations with fluorescence quenching. Affinity constants are reported, showing the high sensitivity of the interaction to the degree of acetylation of chitosan and barely dependent on the molecular weight. We propose that the mechanism of SYBR Gold fluorescence quenching is governed by both static and dynamic quenching.

Concepts: DNA, Fluorescence, Electron, Molecular biology, Ethidium bromide, Atomic mass unit, Agarose gel electrophoresis, Quenching

22

So far, very few numbers of chemosensors for Cr3+ ion have been reported. However, the main drawback of reported receptors are the lack of selectivity and other trivalent cations such as Fe3+, Al3+ and anions like F- and -OAc frequently interfere with such assays. This paper present the synthesis, characterization & sensor studies of Schiff base containing naphthalene moiety which selectively detect Cr3+ ion by chemodosimetric approach. Using FT-IR, 1H NMR, 13C NMR and ESI mass spectroscopic techniques the probe was characterized. This receptor exhibit more selectivity and sensitivity towards Cr3+ than other divalent and trivalent cations like Mn2+, Zn2+, Co2+, Ni2+, Cd2+, Cu2+, Hg2+, Fe3+, and Al3+ ions. After the addition of chromium ion the receptor get change from yellow to colorless in aqueous medium. But no color change was observed on the addition of other metal ions. Using UV-Vis and PL studies, it was confirmed that the selective hydrolysis of imine group of receptor by Cr3+ ions takes place with high fluorescence enhancement that is corresponding to 1-naphthylamine. Receptor acts as selective chemodosimeter for Cr3+ ions with 2:1 stoichiometry and micro molar detection limit. This chemodosimetric approach was applied successfully for bio-imaging of HeLa cells.

Concepts: Electron, Spectroscopy, Signal transduction, Hydrogen, Nuclear magnetic resonance, Ion, Solid, Ionic bond

0

Methylglyoxal (MGO) is one of the most important active carbonyl compounds in living organisms. It is a metabolic by product of glycolysis. MGO participates in glycosylation of proteins and nucleic acids to trigger carbonyl stress, inducing pathological status and even exacerbateing the development of chronic degenerative diseases. In order to study the diseases caused by MGO, it is meaningful for us to develop methods that could efficiently detect MGO. In our work, a new two-photon fluorescent turn-on probe which named NP has been designed which was made up of naphthalimides dye as the two-photon fluorescent platform and the o-phenylenediamine as recognition site. When reacted with MGO, NP showed excellent sensitivity and selectivity. Based on the two-photon fluorescence imaging technology, NP has firstly successful application in living cells, tissues and zebrafish to detecting MGO.

0

In this work, we report an environment friendly core-shell material based on Carbon Dot core and Molecularly Imprinted Polymer shell as sensor for highly selective fluorescence detection of ketoprofen. The Carbon Dots (CDs) were prepared by a hydrothermal method and the polymer layer around the CDs core was synthesised by sol-gel polymerisation. The prepared material was characterized by Fluorescence Spectroscopy, FT-IR Spectroscopy and Transmission Electron Spectroscopy (TEM). Fluorescence from the Carbon Dots- Molecularly Imprinted Polymer (CDs-MIP) was found to quench selectively in the presence of ketoprofen and quenching effect was found to be greater than for Non-Imprinted Polymer (CDs-NIP) which indicated the potential of CDs-MIP as a fluorescence sensing material for ketoprofen. The imprinting factor was obtained to be 2.35. Under optimized conditions, a linear response was obtained in the concentration range from 0.039 to 3.9 μM with a detection limit of 0.01 μM. The correlation coefficient was 0.999. The developed sensor was applied to determination of ketoprofen in human serum and urine samples with good recoveries ranging from 96 to 104% indicating successful application of the proposed sensor in biological fluids.

0

Carbazole - Rhodanine conjugate is an effective fluorescent host for silver ions through fluorometric transformation from green to red color with a hyperchromic emission. An intramolecular charge transfer process derived from carbazole towards rhodanine favors interaction of thiocarbonyl S and carboxylic acid O of the rhodanine moiety towards Ag+ ion. Carbazole - rhodanine dyad accomplishes the lowest detection limit of 12.8 × 10-9 M and high quantum efficiency. A fluorescence reversibility of the probe with I- ion surges reutilization of sensor molecule as an Ag+ ion probe with minimal loss in the fluorescent efficiency. This fluorescent ligand is a biocompatible probe and is also a proficient candidate for fluorescent imaging of Ag+ ion in live cells.

0

In this work, we report a dual use of highly fluorescent N- and O-doped carbon dots (CDs) for rapid and high-throughput trace analysis of iron in water and organic phases. The CDs are rapidly synthesized in a sealed vessel via microwave irradiation within 5 min, and they exhibit high quantum yields of 80% with sensitive quenching responses to iron contents. Combined with a microplate fluorescence reader, a rapid and high-throughput assay for ions is further developed. The whole process from the CD synthesis to the detection output can be accomplished within 15 min. The limits of detection for Fe3+ in aqueous solution and ferrocene in organic gasoline are determined down to 0.05 mM. Furthermore, this method has been successfully used to determine the level of irons in real gasoline for quality evaluation. The results have an excellent agreement with atomic absorption spectrophotometric measurements. The CD-based facile assay with lower cost, use of less sample, and higher-throughput holds great promise as a powerful tool for iron detection in water and organic phase samples.