Fluorescence Intensity Of Rhodamine 6G Research Articles

A hydrogel optical fibre sensor for rapid on-site ethanol determination.

Ethanol plays a critical role in the modern chemical industry, food production, and medical research. Given its wide applications, the detection of ethanol concentration is very necessary. In this paper, a fibre device for rapid ethanol detection is proposed. The sensing head was fabricated with multimode fibre. The hydrogel was photo-cured on the fibre tip from polyethylene glycol diacrylate (PEGDA). In the hydrogel, rhodamine 6G (R6G) was immobilized as the fluorescent indicator. The sensor was designed based on the swelling behaviour of the hydrogel in liquid. The transparency of the hydrogel was modulated by the component of the water-ethanol mixture, thus, the fluorescence intensity of R6G was monitored for the determination of ethanol. Within the range of 0-62.2 vol%, the detection limit (LOD) was 0.4 vol%. A detailed comparison with other detection methods showed that the proposed sensor has the advantages of being single-ended, low LOD, cost-effective, and easy to prepare. It has great potential for on-site ethanol detection applications.

Fluorescence quenching determination of tetracyclines based on the synergistic oxidation effect between Fe3O4 nanoparticles and tetracyclines

In recent years, tetracyclines (TCs) is a hot research topic. Herein, we report an interesting discovery using the complexation of oxytetracycline and metal ions. In this study, according to the properties of Fe3O4 nanoparticles (Fe3O4 NPs) as a nanoenzyme, it can be used to catalyze the oxidation of KI by H2O2 to produce while at the same time binds to rhodamine 6G (Rh6G) to form a conjoined particle (Rh6G ∼ I3)n, leading to a decrease in the fluorescence intensity of Rh6G. However, in the presence of TCs, Fe3O4 NPs have a synergistic effect with TCs, leading to enhanced catalytic activity, as well as better selectivity compared to the activity of other reducing enzymes. Consequently,the fluorescent signal based on a resonance scattering effect between Rh6G and is dependent on the concentration of TCs, thus achieving highly facile and robust detection of TCs. The limits of detection (LOD) of the method were 20 nM, 10 nM and 40 nM for oxytetracycline(OTC), tetracycline(TC) and chlortetracycline(CTC), respectively. Most importantly, the method can be successfully applied to the detection of TCs in milk, eggs, and honey. The recoveries of spiked samples ranged from 83.11 to 118.95%. Thus, a stable, hands-on strategy for the detection of TCs is proposed, which has potential applications in the field of food safety and environmental protection.

Spectrofluorimetric Determination of Some N. Containing Medicines Using Rhodamine 6G as a Chromogenic Reagent

A sensitive spectrofluorimetric method has been developed for the analysis of some medicines containing primary, secondary, and tertiary amino groups, namely Diclofenac (DIC), Domperidone (DOM), Famotidine (FAM), and Propranolol (PRO), in their pure and medicinal forms. The method is based on the quenching of the fluorescence intensity of rhodamine 6G (R6G) through the formation of ion-pair complexes between the above medicines and the R-6G reagent, which is measured at 552 nm after excitation at 402 nm. The calibration graphs were rectilinear in the concentration ranges of 0.10- 9.00, 0.05-15.00, 0.10-14.0 and 0.05-5.00 µg mL-1 for above medicines respectively. The recovery (%) values were ranged between 99.45%- 100.97%. The detection limits ranged in the concentration of 0.243-0.754 µg/mL, and the limits of quantitation were 0.806- 2.420 µgmL-1 for all drugs. The method was successfully applied for the determination of these drugs in their pharmaceutical preparations.

Fluorescence manipulation from graphene and hydrogen-terminated graphene covered Au nanoparticles

This paper presents the fluorescence manipulation of Rhodamine-6G (R6G) due to Au nanoparticles (Au-NPs) covered by pristine graphene and hydrogen-terminated graphene. By taking florescence signals of R6G on a quartz substrate as the standard reference, we observe an ∼fourfold increase in fluorescence intensity of R6G on bare Au-NPs deposited on the quartz substrate. However, this enhancement reduces to ∼1.8-fold when Au-NPs are covered by H-terminated graphene. In the case of Au-NPs covered by pristine graphene, the fluorescence of R6G is significantly quenched by a factor of ∼7.6-fold. The resulting fluorescence level can be attributed to the local field enhancement from Au-NPs and the quenching effect of graphene in the Au–graphene hybrid nanostructure, which are confirmed by our controlled experimental and simulation results. Our work reveals that the surface modification of metal NPs by graphene materials would bring a great impact on fluorescence, providing a simple approach for artificially manipulating fluorescence for specific molecular sensing, detecting, and imaging.

FLUORESCENCE CHARACTERISTICS OF RHODAMINE 6G AND RHODAMINE C IN WATER-MICELLAR SURFACTANT ENVIRONMENTS

The influence of cationic, anionic, nonionic surfactants and their mixtures on the fluorescence characteristics of rhodamine 6G and Rho-damine C solutions has been investigated. The fluorescence intensity of aqueous solutions of rhodamine 6G and in the presence of cetylpyridinium chloride and sodium dodecyl sulfate has almost unchanged throughout the pH range. The fluorescence intensity of aqueous and water-micellar rhodamine C solutions has been increased in the pH 1-4 range; the signal has been remained unchanged at high pH values. The studies have been carried out at pH 4 for rhodamine 6G and at pH 10 for rhodamine C. The fluorescence characteristics of water-micellar dye - surfactant - non-ionic surfactant systems have been performed at a concentration of Triton X-100 of 3.4·10‑2 mol/l. The interaction with cationic surfactants has shown differences character between the I=f(n) dependences for aqueous solutions of highly hydrophobic rhodamine 6G and more hydrophilic rhodamine C. The study of the effect of the hydrocarbon radical length on the intensity of the fluorescence of rhodamine 6G and rhodamine C has been carried out at two concentrations of cationic surfactants: under the condition of the formation of stoichiometric associates dye with cationic surfactant and in the region of the micellar concentrations of cationic surfactants. The character of the influence of the length of the hydrocarbon radical cationic surfactants on the fluorescence intensity of the dyes can be explained by the increasing role of hydrophobic interactions and the enhancement of solubilization in systems involving long-chain surfactants. The difference in the nature of the associates of rhodamine 6G and rhodamine C with hydrophobic and moderately hydrophobic cationic surfactants has been counterbalanced in the presence of Triton X-100. Reduction of fluorescence intensity of rhodamine 6G in domicile solutions of anionic sodium dodecyl sulfate has been established. The method of fluorescence detection of sodium dodecyl sulfate in reaction with rhodamine 6G has been proposed. The method has been tested in determining of anionic surfactants in the waters after washing clothes.

Investigating the Energy Transfer from Dye Molecules to DNA Stabilized Au Nanoparticles.

Double-stranded DNA stabilized gold nanoparticles (Au NPs) are synthesized by chemical reduction method and characterized with different spectroscopic techniques such as UV-Visible absorption, Fourier transform infrared (FTIR), & circular-dichroism (CD) as well as transmission electron microscopy (TEM). These NPs show absorption maximum at 520nm and size of most of the particles are of the order of 3.5±1.0nm. These Au NPs show crystalline nature as confirmed from electron diffraction pattern. The effect of formation of Au NPs on the macromolecule has been studied using infrared and circular dichroism spectroscopy. Formation of NPs causes conformational changes in the DNA molecules. These Au NPs are further used as resonant energy acceptor of fluorescence emission from dye molecules (Rhodamine 6G). The fluorescence intensity of Rhodamine 6G (R6G) is quenched in presence of Au NPs. The effect of DNA molecules on the fluorescence quenching and the rate of energy transfer from R6G molecules to Au NPs have been explored.

Влияние наночастиц серебра на интенсивность флуоресценции Родамина 6G и Сульфородамина 101

Влияние наночастиц серебра на интенсивность флуоресценции Родамина 6G и Сульфородамина 101

Fluorescence quenching of rhodamine 6G by 1,3,5-Trinitroperhydro-1,3,5- triazine entrapped in porous sol–gel silica

Fluorescence quenching of laser dye rhodamine 6G by codoping 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) in porous sol–gel silica is reported. It was found that the fluorescence intensity of rhodamine 6G decreases with increase in the concentration of RDX. Both the samples, predoped cylindrical shaped and postdoped thick film on glass substrate with RDX show the similar fluorescence quenching behavior. Emission spectra show slight red shifting with the increase in RDX concentration. An electron-transfer donor–acceptor mechanism is proposed for the observed fluorescence quenching. On the basis of these results, candidature of dye doped porous sol–gel silica as a sensor for explosive detection seems to be promising.

Fluorescence spectral detection of cysteine based on the different medium-coated gold nanorods-Rhodamine 6G probe: From quenching to enhancement

Au nanoparticles-based fluorescence quenching has been widely used for many analytes due to its high sensitivity and rapid response. However, the effects of different coating agents of Au nanorods on the assays performance remain unclear. For the first time, we demonstrated that the coating agents play a significant role in Au nanorods-based fluorescence quenching and recovery on Rhodamine 6G (R6G). Polystyrenesulfonate (PSS)-coated Au nanorods could almost totally quench the fluorescence intensity of R6G, whereas cetyltrimethyl ammonium bromide (CTAB)-coated Au nanorods and bare Au nanorods only have little effect on the fluorescence of R6G. The addition of cysteine to PSS-coated Au nanorods-R6G makes the fluorescence recover gradually, even greater than the original fluorescence intensity of R6G. Thus the PSS-coated Au nanorods-R6G could be served as a fluorescent probe to detect cysteine. The fluorescence intensity change of PSS-coated Au nanorods-R6G probe is linear with logarithm of Cys concentration over the range from 0.01 to 2.5μg/mL. The results provide theoretical guidance for further improving Au nanorods-based fluorescence quenching and detection of protein molecules by the fluorescence off-on mechanism.

Ultra-sensitive nanofiber fluorescence detection in a microfluidic chip.

We report an ultra-sensitive and robust fluorescence sensor made by using a biconical taper with a waist diameter of 720 nm for both excitation and fluorescence collection. To enhance the stability of the fluorescence sensor, the biconical taper has been embedded in a 125 µm wide microchannel with a detection length of 2.5 cm. Investigated by measuring the fluorescence intensity of rhodamine 6G (R6G), the sensor shows a detection limit down to 100 pM, with excellent reversibility in a concentration range of 0–10 nM. The sensor has also been applied to quantum dot (QD)-labeled streptavidin measurements, yielding a detection sensitivity down to 10 pM for QDs. In addition, the small sample volume (ca. 500 nL), high sampling throughput, and seamless connection between the biconical taper and standard optical fibers offer a number of attractive advantages for chemical and biosensing applications.

Manipulating fluorescence intensity with mechanical strains

In this paper we show that the fluorescence of rhodamine 6G (R6G) can be manipulated by applying mechanical strains to gold nanoparticles (GNs) sandwiched in graphene/GNs/polydimethylsiloxane (graphene/GNs/PDMS) structure. The fluorescence intensity of R6G on the graphene/GNs/PDMS sample shows a gradual increase with the mechanical strain. However, the fluorescence intensity of R6G on the graphene/PDMS structure without the GNs buried in between is almost unchanged under the action of the external mechanical strain. Experiment results indicate that the gap distance change between the GNs is the main cause of the fluorescence intensity increase and graphene, as a passivation layer, does not block the energy transfer from R6G to GNs. Compared with that tuning the gap distance between GNs by preparing various GNs samples, applying macroscopic mechanical strain on GNs is a simple way to manipulate the fluorescence intensity of a specific material and brings a new perspective for optoelectronic applications.

The structure, morphology, and the metal-enhanced fluorescence of nano-Ag/ZnO core–shell structure

Nano-polyc rystalline silver (Ag) particles with the diameter of 60 nm were synthesized by the reducing agent sodium citrate. An amorphous zinc oxide (ZnO) shell layer was then coated on the surface of silver particles using wet chemical method. The Ag/ZnO core–shell structure was characterized by scanning electron microscope, transmission electron microscopy, ultraviolet–visible spectroscopy and fluorescence (FL) measurement. The results showed that nano-Ag/ZnO core–shell particles with an average diameter of ~100 nm were prepared successfully, and the FL intensity of Rhodamine 6G (R6G) mixed with Ag/ZnO nanoparticle was 53 % greater than that of the same amount of R6G without any nanoparticles, which may be related to the effect of surface plasmon resonance.

Counting single Rhodamine 6G dye molecules in organosilicate nanoparticles

Rhodamine 6G (R6G) dye molecules have been embedded into organosilicate nanoparticles to improve thermal and chemical stability of these marker molecules. We demonstrate that the well-established method of optical single-particle microscopy can be used to determine the number of dye molecules per nanoparticle in such hybrid materials. Analysing the fluorescence intensity of R6G in single nanoparticles, we obtain an average number of 1.3–1.7 dye molecules per nanoparticle as compared to 1 R6G per particle obtained from ensemble experiments. The blinking behaviour of embedded R6G can be described by a power law with an exponent αon/off=-1.7. Ensemble measurements complete the optical characterization of the nanoparticles, which reveals no pronounced R6G aggregate formation.

Optical characterization of the heating performance of microchannel fluid flow

Abstract The temperature dependent quantum efficiency of fluorescent dyes can be used to measure changes in temperature of the fluorescent dye molecules. This paper describes the use of Rhodamine dye as a temperature sensitive based fluorescence indicator for the characterization of heating in a pressure driven microfluidic device with high spatial resolution. A microheating element is used to control the temperature of the fluid in order to create localized heating in the microchannel. The temperature dependent fluorescence intensity of Rhodamine 6G for a concentration of 1 mmol / L is characterized with a 5th order polynomial then used to detect the temperature of the fluid in a microchannel. Fluid temperatures in the range of 20 – 85 ° C are measured with an uncertainty of 2 ° C using a confocal fluorescence microscope. This method enables the characterization, imaging and mapping of three-dimensional temperature gradients within a microchannel.

Fluorescence of Rhodamine 6G on Hydrotalcite —Possibility of Alcohol Sensing—

Abstract The fluorescence intensity of Rhodamine 6G (R6G) introduced on hydrotalcite by the rehydration method was determined to depend strongly on the alcohol vapor pressure, whereas that of R6G simply adsorbed on hydrotalcite had low dependence on the vapor pressure. The intensity decreased with an increase in pressure, and the change in intensity was reversible. The degree of change differed according to the alcohol used and seemed to be related to the saturated vapor pressure of the alcohols.

Fluorescence resonance energy transfer between acridine orange and rhodamine 6G and analytical application in micelles of dodecyl benzene sodium sulfonate

A new method for the determination of erythromycin by energy transfer fluorescence quenching of acridine orange (AO)—rhodamine 6G (R6G) in micelles solution studied and established. It was found that the effective energy transfer could occur between AO and R6G in the dodecyl benzene sodium sulfonate at λ ex / λ em = 470 / 553 nm and Britton–Robinson buffer (BR, pH=5.72). The fluorescence intensity of R6G had been increased sharply. Erythromycin diminished the fluorescence intensity of R6G. The detection limit was up to 0.316 mg l −1. The range of determining concentration of erythromycin was 0.75–15 mg l −1. The relative standards deviation were 0.66–1.38% for six parallel determinations of erythromycin. The recoveries of erythromycin were 96.95–101.41%. The measurement was applied to the determination of capsules of erythromycin with good results.

Photoblinking of Rhodamine 6G in Poly(vinyl alcohol): Radical Dark State Formed through the Triplet

We investigate the fluorescence intensity of rhodamine 6G in poly(vinyl alcohol) as a function of excitation intensity, illumination time, the presence of oxygen, and temperature. The variations in emissivity (or fluorescence brightness) are attributed to a dark state, which shows populating kinetics resembling those of the triplet state, but a much longer lifetime. We simulate the observed kinetics by a four-level model, in which a long-lived dark state is formed through the triplet as an intermediate state. The weak temperature dependence of the lifetime of the dark state points to electron tunneling as the main recovery process. This intermolecular mechanism also explains the observed broad distribution of lifetimes. An electron-spin-resonance experiment confirms the assignment of the dark state to a radical. For the first time, photoinduced charge transfer is identified as a source of blinking in single-molecule measurements.

Changes in membrane potential and membrane fluidity in Tetrahymena pyriformis in association with chemoreception of hydrophobic stimuli: fluorescence studies.

The fluorescence intensity of rhodamine 6G (Rh6G) and 1,6-diphenyl-1,3,5-hexatriene (DPH) in the presence of Tetrahymena pyriformis was measured to monitor changes in the membrane potential and in the gross structure of the surface membrane in response to chemical stimuli. So-called "odorants" for higher vertebrates, which are usually uncharged and hydrophobic compounds, were chosen as chemical stimuli for a model study of the olfactory response. The fluorescence intensity of Rh6G started to increase at the chemotactic thresholds of the stimuli, indicating that negative chemotaxis of T. pyriformis to the hydrophobic stimuli is induced by depolarization of the cell. The fluorescence intensity of DPH increased in close association with chemoreception of the hydrophobic stimuli. The increase in the fluorescence intensity was ascribed mainly to uptake of DPH, suggesting that gross structural changes of the surface membrane occur with the reception of hydrophobic stimuli. The membrane fluidity determined by fluorescence polarization of DPH increased in close association with the chemoreception of the hydrophobic stimuli. Inorganic salts such as NcCl, KCl, and CaCl2 did not change the DPH fluorescence intensity or the fluorescence polarization, although these stimuli induced depolarization and negative chemotaxis in T. pyriformis.

Fluorescence changes of rhodamine 6G associated with chemotactic responses in Tetrahymena pyriformis

1. 1. The chemotactic responses in Tetrahymena to various inorganic salts and octanol were examined quantitatively. Tetrahymena exhibited negative chemotaxis to the salts and octanol above respective threshold concentrations. The order of the threshold of salts was NH 4Cl ≅ NaCl > LiCl > KCl > CaCl 2 ≅ MgCl 2 > LaCl 3. 2. 2. Fluorescence intensity of rhodamine 6G added to Tetrahymena suspension increased with increasing concentration of stimuli above respective thresholds. The fluorescence changes were closely correlated with the chemotactic responses for all the chemical stimuli examined. 3. 3. Measurements of the fluorescence intensity of the supernatant of dy- Tetrahymena suspension showed that the dye was taken up by Tetrahymena and the addition of salts led to a release of the dye into an external medium. 4. 4. The adsorption of dye on the liposome also led to the quenching of its fluorescence. Addition of salts to the dye liposome suspension brought about an increase of the fluorescence. The order of the effectiveness was mono-valent < divalent < trivalent. The fluorescence intensity changed linearly with log[K] out in the presence of valinomycin. It was concluded that the changes in fluorescence on rhodamine 6G reflect both changes in the surface potential and those in the intramembrane diffusion potential, which in turn reflect changes in the total membrane potential across the membrane. We suggest that the surface potential as well as the diffusion potential contributes to the changes in the membrane potential in Tetrahymena associated with the chemotactic responses.