Studies on fluorescence of cellulosics

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 504-508 ◽  
Author(s):  
Alain Castellan ◽  
Reinaldo Ruggiero ◽  
Elisabete Frollini ◽  
Ludmila A. Ramos ◽  
Christine Chirat
Keyword(s):  
Solid State ◽  
Microcrystalline Cellulose ◽  
Woody Plants ◽  
Average Molecular Weight ◽  
Homogeneous Medium ◽  
Fluorescence Emission ◽  
Excitation Wavelength ◽  
Experimental Conditions ◽  
Fluorescence Emission Spectra ◽  
Cotton Linters

Abstract Steady-state fluorescence emission spectra of various celluloses were measured at an excitation wavelength of 320 nm. Various spectra recorded in the solid state were compared: (1) ECF bleached papers made of hardwood, the anhydroglucose units of which were chemically modified at C1 and C6 or C2 and C3 positions with carboxylic groups; (2) microcrystalline cellulose; (3) cotton linters; and (4) delignified sisal fibers (mercerized or not). Fluorescence emission was quite independent of the carboxylic acid content and average molecular weight (determined by viscosimetry) of the cellulose polymers. Microcrystalline cellulose (Avicel), cotton linters, and mercerized delignified sisal cellulose were acetylated in homogeneous medium (DMAc/LiCl as solvent system) to obtain soluble polymers in dichloromethane for comparison of spectra recorded in the solid and liquid states. Fluorescence of cellulose acetates in solution (CH2Cl2) and in the solid state was compared under similar experimental conditions to non-esterified celluloses in the solid state. The importance of the solid state for fluorescence emission could be demonstrated. Fluorophores are present in minute amounts in the polymer and their favorable energy transfer for excitation in the solid state likely enhances fluorescence emission. Among numerous fluorophores, dityrosine appeared to be a good candidate for fluorescence because it displayed emission in the fluorescence range of cellulose. Dityrosine is an amino acid involved in the lignification of non-woody plants. Mercerized sisal impregnated with tyrosine in the presence of peroxidase and hydrogen peroxide did not show enhanced emission, in contrast to para-hydroxycinnamic acid (coumaric acid), which is also involved in the lignification process at least for non-woody plants. The origin of cellulose fluorescence remains uncertain and appears to have several origins. This study clearly underlines the importance of the solid state for enhancing fluorophore emission.

Multiple excitation wavelength fluorescence emission spectra technique for discrimination of phytoplankton

2010 ◽  
Vol 9 (1) ◽  
pp. 16-24 ◽  
Author(s):  
Xupeng Hu ◽  
Rongguo Su ◽  
Fang Zhang ◽  
Xiulin Wang ◽  
Hongtao Wang ◽  
...  
Keyword(s):  
Fluorescence Emission ◽  
Emission Spectra ◽  
Excitation Wavelength ◽  
Fluorescence Emission Spectra

A Novel Near-Infrared Fluorescence Sensor for H2O2 Based on N-Acetyl-L-Cysteine-Capped Gold Nanoparticles

2017 ◽  
Vol 46 ◽  
pp. 234-240
Author(s):  
Wen Juan Dong ◽  
Ji Yan Han ◽  
Xin Wu ◽  
Li Fan ◽  
Wen Ting Liang
Keyword(s):  
Hydrogen Peroxide ◽  
Gold Nanoparticles ◽  
Fluorescence Quenching ◽  
Near Infrared ◽  
Fluorescence Probe ◽  
Fluorescence Emission ◽  
Excitation Wavelength ◽  
Experimental Conditions ◽  
Time Resolved ◽  
Near Infrared Fluorescence

A novel near-infrared fluorescence quenching method has been developed for the determination of hydrogen peroxide based on N-acetyl-L-cysteine-capped gold nanoparticles (NAC-AuNPs) as a fluorescence probe. The prepared gold nanoparticles with the size of about 1.91 nm exhibited strong near-infrared fluorescence emission at 693 nm with excitation wavelength at 450 nm in aqueous solution. The fluorescence intensity of NAC-AuNPs was quenched dramatically by adding hydrogen peroxide. Therefore, it could be used to detect hydrogen peroxide based on the fluorescence quenching intensity was linear with the concentration of hydrogen peroxide. Under the optimal experimental conditions, the linear range and detection limit were 1.0×10-6 –3.0×10-2 mol/L and 1.0×10-7 mol/L, respectively. The possible quenching mechanism was investigated by time-resolved fluorescence spectroscopy. The proposed method was simple, sensitive and showed good repeatability and stability.

Note on Solid State Fluorescence Emission of Ochratoxins A and B on Silica Gel

1970 ◽  
Vol 53 (4) ◽  
pp. 696-697
Author(s):  
Fun Sun Chu
Keyword(s):  
Solid State ◽  
Ochratoxin A ◽  
Silica Gel ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluorescence Emission Spectra ◽  
Ochratoxin B ◽  
Solid State Fluorescence

Abstract The fluorescence emission spectra of ochratoxins A and B on silica gel have been determined. The emission maxima for both toxins were found to be around 475 nm, with excitation maxima at 340 nm for ochratoxin A and 325 nm for ochratoxin B.

scholarly journals Solid state fluorescence of proteins in high throughput mode and its applications

F1000Research ◽  
2019 ◽  
Vol 2 ◽  
pp. 82
Author(s):  
Saurabh Gautam ◽  
Munishwar N Gupta
Keyword(s):  
Solid State ◽  
High Throughput ◽  
Fluorescence Spectra ◽  
Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Fluorescence Emission ◽  
Resonance Energy ◽  
Emission Spectra ◽  
Fluorescence Emission Spectra ◽  
Simple Method

Direct comparison between fluorescence spectra of a sample in solution and solid state form is valuable to monitor the changes in protein structure when it is “dried” or immobilized on a solid surface (for biocatalysis or sensor applications). We describe here a simple method for recording fluorescence emission spectra of protein powders without using any dedicated accessory for solid samples in a high-throughput format. The 96-well plate used in our studies, was coated black from all the sides and the excitation and emission paths are identical and are from the top of the well. These two features minimize scatter and provide fairly noise free spectra. Even then the fluorescence intensity may be dependent upon many factors such as the extent of protein aggregation, morphology and sizes of the protein particles. Hence, (changes in) λmax emission may be a more reliable metric in the case of fluorescence spectra of proteins in the solid state. However, any large changes in the intensity could indicate changes in the microenvironment of the fluorophore. The fluorescence emission spectra were blue-shifted (4 to 9 nm), showed an increase in the intensity for different proteins studied upon lyophilization, and were similar to what has been reported by others using available commercial accessories for solid state samples. After validating that our method worked just as well as the dedicated accessories, we applied the method to compare the fluorescence emission spectra of α-chymotrypsin in solution, precipitated form, and the lyophilized powder form. We further examined the fluorescence emission spectra of green fluorescent protein (GFP) in solution and solid form. We also analyzed fluorescence resonance energy transfer (FRET) between tryptophan (Trp57) and the cyclic chromophore of GFP. These findings pointed towards the change in the microenvironment around the cyclic chromophore in GFP upon lyophilization.

scholarly journals Solid state fluorescence of proteins in high throughput mode and its applications

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 82
Author(s):  
Saurabh Gautam ◽  
Munishwar N Gupta
Keyword(s):  
Solid State ◽  
High Throughput ◽  
Fluorescence Spectra ◽  
Tertiary Structure ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Red Shift ◽  
Solid Samples ◽  
Fluorescence Emission Spectra ◽  
Simple Method

A simple method to determine fluorescence emission spectra of proteins in solid state is described. The available commercial accessories can only accommodate solid samples and hence do not allow a direct comparison between fluorescence spectra of a sample in solution and solid state form. Such comparisons are valuable to monitor the changes in protein structure when it is “dried” or immobilized on a solid surface (for biocatalysis or sensor applications). The commercially available accessories also do not allow working in a high throughput mode. We describe here a simple method for recording fluorescence emission spectra of protein powders without using any dedicated accessory for solid samples. This method works with a 96-well plate format. It enables the comparison of fluorescence spectra of a sample in a solid state with solution spectra, using comparable quantities of protein. The fluorescence emission spectra were blue-shifted (4 to 9 nm), showed an increase in the intensity for different proteins studied upon lyophilization, and were similar to what has been reported by others using available commercial accessories for solid state samples. After validating that our method worked just as well as the dedicated accessories, we applied the method to compare the fluorescence emission spectra of α-chymotrypsin in solution, precipitated form and the lyophilized powder form. α-Chymotrypsin in solution showed a λmax of 335 nm while a high-activity preparation of the same enzyme for non-aqueous media, known as enzyme precipitated and rinsed with propanol (EPRP), showed an increase in the intensity of the fluorescence emission spectra. However, there was a small red shift of 2 nm (λmax of 337 nm) in contrast to lyophilized powder which showed a λmax of 328 nm. This is due to a difference in the tertiary structure of the protein as well as the microenvironment of aromatic residues between the two preparations. We further examined the fluorescence emission spectra of green fluorescent protein (GFP) in solution and solid form. The relative fluorescence intensity of lyophilized GFP powder was decreased significantly to 17% as compared to GFP in solution, and showed a red shift of 4 nm in the emission λmax. It was found that fluorescence resonance energy transfer (FRET) between tryptophan (Trp57) and the cyclic chromophore of GFP was significantly diminished. This indicated the change in the microenvironment around the cyclic chromophore in GFP upon lyophilization.

scholarly journals Can Parietin Transfer Energy Radiatively to Photosynthetic Pigments?

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1741
Author(s):  
Beatriz Fernández-Marín ◽  
Unai Artetxe ◽  
José Becerril ◽  
Javier Martínez-Abaigar ◽  
Encarnación Núñez-Olivera ◽  
...  
Keyword(s):  
Photosynthetic Pigments ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Main Role ◽  
Transfer Energy ◽  
Experimental Conditions ◽  
Fluorescence Emission Spectra ◽  
Kinetic Assessment ◽  
Yellow Orange

The main role of lichen anthraquinones is in protection against biotic and abiotic stresses, such as UV radiation. These compounds are frequently deposited as crystals outside the fungal hyphae and most of them emit visible fluorescence when excited by UV. We wondered whether the conversion of UV into visible fluorescence might be photosynthetically used by the photobiont, thereby converting UV into useful energy. To address this question, thalli of Xanthoria parietina were used as a model system. In this species the anthraquinone parietin accumulates in the outer upper cortex, conferring the species its characteristic yellow-orange colouration. In ethanol, parietin absorbed strongly in the blue and UV-B and emitted fluorescence in the range 480–540 nm, which partially matches with the absorption spectra of photosynthetic pigments. In intact thalli, it was determined by confocal microscopy that fluorescence emission spectra shifted 90 nm towards longer wavelengths. Then, to study energy transfer from parietin, we compared the response to UV of untreated and parietin-free thalli (removed with acetone). A chlorophyll fluorescence kinetic assessment provided evidence of UV-induced electron transport, though independently of the presence of parietin. Thus, a role for anthraquinones in energy harvesting is not supported for X. parietina under presented experimental conditions.

scholarly journals One-Pot Hydrothermal Synthesis of Carbon Dots as Fluorescent Probes for the Determination of Mercuric and Hypochlorite Ions

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1831
Author(s):  
Hsin Lee ◽  
Yen-Chang Su ◽  
Hsiang-Hao Tang ◽  
Yu-Sheng Lee ◽  
Jan-Yee Lee ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Fluorescent Probes ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Tap Water ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Excitation Wavelength ◽  
One Pot ◽  
Fluorescence Emission Spectra

Nitrogen and sulfur codoped carbon dots (NSCDs) were synthesized via a one-pot hydrothermal method, and citric acid, ethylenediamine, and methyl blue were used as precursors. The obtained NSCDs were spherical with an average size of 1.86 nm. The fluorescence emission spectra of the NSCDs were excitation independent and emitted blue fluorescence at 440 nm with an excitation wavelength at 350 nm. The quantum yield of the NSCDs was calculated to be 68.0%. The NSCDs could be constructed as fluorescent probes for highly selective and sensitive sensing mercuric (Hg2+) and hypochlorite (ClO−) ions. As the addition of Hg2+ or ClO− ions to the NSCDs, the fluorescence intensity was effectively quenched due to dynamic quenching. Under the optimal conditions, the linear response of the fluorescence intensity ranged from 0.7 μM to 15 μM with a detection limit of 0.54 μM and from 0.3 μM to 5.0 μM with a limit of detection of 0.29 μM for Hg2+ and ClO− ions, respectively. Finally, the proposed method was successfully used for quantifying Hg2+ and ClO− ions in spiked tap water samples.

scholarly journals Synthesis and electro-optical properties of fluorene containing blue luminescent rod-coil homopolymers with pendant pyridine

2017 ◽  
Vol 35 (1) ◽  
pp. 217-224
Author(s):  
Duryodhan Sahu ◽  
Subhendu Chakroborty
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Average Molecular Weight ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Decomposition Temperature ◽  
High Thermal Stability ◽  
Photoluminescence Spectra ◽  
Fluorescence Emission Spectra ◽  
Good Solubility

AbstractTwo well defined, blue luminescent homopolymers containing 9,9-diethylfluorene core with electron withdrawing pendant pyridine, Suzuki-coupled with the corresponding borolane of decoxy phenyl (PFPA) and naphthalene (PFNA) have been designed and synthesized efficiently. The obtained rod-coil polymers have the average molecular weight of 15212 (PFPA) and 15130 (PFNA) with polydispersity indices (PDIs) 1.07 and 1.3, respectively. The polymers have good solubility and high thermal stability with the decomposition temperature of 362 °C (PFPA) and 367 °C (PFNA) correspondingly. Furthermore the optical and electrochemical properties of the polymers have been investigated. The polymers exhibited photoluminescence (PL) maxima at 410 nm (PFPA) and 414 nm (PFNA) excited at 340 nm, as stable blue luminescence polymers at low concentration of 10−6 M with a quantum yield of 0.64 and 0.62, respectively. In addition the annealed (150 °C) polymer films showed better stability of its photoluminescence spectra. Absorbance and fluorescence emission spectra of PFPA and PFNA were compared in order to evaluate the effects of substituent, phenyl and naphthalene in pyridine pendant fluorene moieties.

scholarly journals Addition of lipid to the photosynthetic membrane: effects on membrane structure and energy transfer.

1981 ◽  
Vol 91 (1) ◽  
pp. 113-125 ◽  
Author(s):  
C O Siegel ◽  
A E Jordan ◽  
K R Miller
Keyword(s):  
Protein Complex ◽  
Freeze Fracture ◽  
Fluorescence Emission ◽  
Freezing And Thawing ◽  
Photosynthetic Membrane ◽  
Experimental Conditions ◽  
Fluorescence Emission Spectra ◽  
Light Reaction ◽  
Complex Ii ◽  
Chlorophyll Protein

We have carried out a series of experiments in which the lipid composition of the photosynthetic membrane has been altered by the addition of lipid from a defined source under experimental conditions. Liposomes prepared by sonication are mixed with purified photosynthetic membranes obtained from spinach chloroplasts and are taken through cycles of freezing and thawing. Several lines of evidence, including gel electrophoresis and freeze-fracture electron microscopy, indicate that an actual addition of lipid has taken place. Structural analysis by freeze-fracture shows that intramembrane particles are widely separated after the addition of large amounts of lipid, with one exception: large hexagonal lattices of particles appear in some regions of the membrane. These lattices are identical in appearance with lattices formed from a single purified component of the membrane known as chlorophyll-protein complex II. The suggestion that the presence of such lattices in lipid-enriched membranes reflects a profound rearrangement of photosynthetic structures has been confirmed by analysis of the fluorescence emission spectra of natural and lipid-enriched membranes. Specifically, lipid addition in each of the cases we have studied results in the apparent detachment of chlorophyll-protein complex II from photosynthetic reaction centers. It is concluded that specific arrangements of components in the photosynthetic membrane, necessary for the normal functioning of the membrane in the light reaction of photosynthesis, can be regulated to a large extent by the lipid content of the membrane.

Visible and Near-Infrared Fluorescence of Crude Oils

1995 ◽  
Vol 49 (6) ◽  
pp. 754-764 ◽  
Author(s):  
Taggart D. Downare ◽  
Oliver C. Mullins
Keyword(s):  
Energy Transfer ◽  
Near Infrared ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Quantum Yields ◽  
Crude Oils ◽  
Excitation Wavelength ◽  
Fluorescence Emission Spectra ◽  
Fluorescence Quantum Yields ◽  
Oil Type

Fluorescence emission spectra and absolute quantum yields have been measured for ten diverse crude oils at various concentrations over a broad range of excitation and emission wavelengths in the visible and the near-infrared. Energy transfer produces large red shifts and large widths in the fluorescence emission spectra for shorter wavelength excitation particularly for heavier crude oils. However, the effects of energy transfer are nearly absent for near-infrared excitation; all crude oils exhibit nearly the same emission spectra for long wavelength excitation. In addition, the fraction of emission resulting from collisional energy transfer relative to nascent emission is almost independent of oil type; it is governed by quantum yield characteristics. Absolute fluorescence quantum yields of ten crude oils (and three rhodamine dyes for validation) were measured with respect to scattering of latex microspheres in distilled water. Fluorescence quantum yields vary systematically with crude oil type as well as excitation wavelength; quantum yields are lower for high fluorophore concentrations (heavy crude oils) and for longer wavelength excitation. Stern-Volmer analyses of the quantum yields indicate that simple models apply and show the relative quenching rates for different excitation wavelengths.

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