scholarly journals A tryptophan synchronous and normal fluorescence study on bacteria inactivation mechanism

2019 ◽  
Vol 116 (38) ◽  
pp. 18822-18826 ◽  
Author(s):  
Runze Li ◽  
Dinesh Dhankhar ◽  
Jie Chen ◽  
Thomas C. Cesario ◽  
Peter M. Rentzepis
Keyword(s):  
Fluorescence Intensity ◽  
Protein Unfolding ◽  
Uv Light ◽  
Quantum Yields ◽  
Continuous Irradiation ◽  
Minute Period ◽  
Bacteria Inactivation ◽  
Tryptophan Residues ◽  
Inactivation Mechanism ◽  
Kinetics Of

The UV photodissociation kinetics of tryptophan amino acid, Trp, attached to the membrane of bacteria, Escherichia coli and Bacillus subtilis, have been studied by means of normal and synchronous fluorescence. Our experimental data suggest that the fluorescence intensity of Trp increases during the first minute of irradiation with 250 nm to ∼ 280 nm, 7 mW/cm2 UV light, and subsequently decreases with continuous irradiation. During this short, less than a minute, period of time, 70% of the 107 cell per milliliter bacteria are inactivated. This increase in fluorescence intensity is not observed when tryptophan is in the free state, namely, not attached to a protein, but dissolved in water or saline solution. This increase in fluorescence is attributed to the additional fluorescence of tryptophan molecules formed by protein unfolding, the breakage of the bond that attaches Trp to the bacterial protein membrane, or possibly caused by the irradiation of 2 types of tryptophan residues that photolyze with different quantum yields.

Synthesizes and Properties Research of a Photochromic Diarylethene Bearing a Hexatomic Ring

2013 ◽  
Vol 830 ◽  
pp. 278-281
Author(s):  
Zhi Yuan Sun ◽  
Wei Wei Geng ◽  
Shou Zhi Pu
Keyword(s):  
Reaction Kinetics ◽  
Fluorescence Intensity ◽  
Uv Light ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Solid Films ◽  
Kinetics Of

A new photochromic diarylethene compound 1-(2-cyan-3-phenyl)-2-[5-(4-cyanobenzene) -2-methyl-3-thienyl] perfluorocyclopentene was synthesized. And their properties inculding photochromis, fluorescence in both hexane and solid films, reaction kinetics of cyclization and cycloreversion were studied. And its absorption maxima were observed at 539 nm in hexane and at 552 nm in PMMA films, respectively, upon irradiation with 313 nm UV light. The fluorescence intensity of diarylethene decreased upon irradiation with 313 nm UV light. Besides, the cyclization and cycloreversion processes of the compound were determined to be the zeroth and first order reaction by UV-Vis spectra, respectively.

Synethesis and Properties of 1-(2-trifluoromethylphenyl)-2-[2-methyl-5-(3-N,N-dimethylphenyl)-3-thienyperfluorocyclopentene

2013 ◽  
Vol 473 ◽  
pp. 77-80
Author(s):  
Zhi Yuan Sun ◽  
Dan Dan Xue ◽  
Shou Zhi Pu
Keyword(s):  
Reaction Kinetics ◽  
Fluorescence Intensity ◽  
Uv Light ◽  
Order Reaction ◽  
First Order Reaction ◽  
Fluorescent Properties ◽  
First Order ◽  
Kinetics Of

An unsymmetrical photochromic diarylethene 1-(2-trifluoromethylphenyl)-2-[2-methyl-5-(3-N,N-dimethylphenyl)-3-thienyperfluorocyclopentene (1a) was synthesized and its photochromism, fluorescent properties and reaction kinetics of cyclization and cycloreversion were studied in detail. The compound exhibited remarkable photochromism and its absorption maxima were observed at 552 nm in hexane and at 569 nm in PMMA films upon irradiation with 297 nm UV light. The fluorescence intensity of diarylethene decreased upon irradiation with 297 nm UV light. In addiation, reaction kinetics of the cyclization and cycloreversion processes of the compound were determined to be the zeroth and first order reaction by UV-Vis spectra, respectively.

Photochromism, Kinetics and Fluorescence of 1-(2-methyl-3-benzofuranyl)-2-[2-methyl-5-(4-cyanophenyl)-3-thienyl]perfluorocyclopentene

2014 ◽  
Vol 886 ◽  
pp. 175-178
Author(s):  
Dan Dan Xue ◽  
Zhi Yuan Sun ◽  
Shou Zhi Pu
Keyword(s):  
Fluorescence Intensity ◽  
Fluorescence Spectra ◽  
Uv Light ◽  
Photochromic Properties ◽  
Strong Fluorescence ◽  
Open Ring ◽  
Kinetics Of ◽  
Hexane Solution

An unsymmetrical photochromic diarylethene compound, 1-(2-methyl-3-benzofuranyl)-2-[2-methyl-5-(4-cyanophenyl)-3-thienyperfluorocyclopentene was synthesized, and its photochromic properties, kinetics of the photochromic cyclization/cycloreversion and fluorescence were investigated in detail. The compound exhibited good photochromism, changing from colorless to red after irradiation with 297 nm UV light, in which absorption maxima were observed at 530 nm in hexane solution. Simultaneously, cyclization/cycloreversion kinetics of this diarylethene was researched. The open-ring isomer of the diarylethene exhibited relatively strong fluorescence at 377 nm in hexane solution (2 × 10-5 mol L-1), when excited at 327 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light. The fluorescence spectra of the diarylethene are depended on the concentration.

Photocatalysis of Coomassie Brilliant Blue Using Clay Mineral

2016 ◽  
Vol 869 ◽  
pp. 765-767 ◽  
Author(s):  
Layane Rodrigues Almeida ◽  
João Sammy Nery Souza ◽  
Edson Cavalcanti Silva Filho ◽  
Josy Anteveli Osajima
Keyword(s):  
Organic Pollutants ◽  
Uv Light ◽  
Brilliant Blue ◽  
Blue Dye ◽  
Secondary Treatment ◽  
Toxic Compounds ◽  
Coomassie Brilliant Blue ◽  
Kinetics Of ◽  
Coomassie Brilliant ◽  
Photocatalytic Processes

The presence of organic pollutants, which cannot be eliminated by conventional processes of primary and secondary treatment, can be problematic. Photocatalytic processes offer an efficient breakdown of organic pollutants into non-toxic compounds such as CO2 and H2O. This paper proposes the use of the titanium dioxide embedded in palygorskite as a photoactive material in the degradation of cationic dye, Coomassie Brilliant Blue. The system was irradiated using UV light for a maximum time of 120 minutes. The concentration of the dye used was 1.0x10-4 mol L-1 in 0.5 g L-1 of the photoactive material. The kinetics of the system was monitored by UV-Vis spectrophotometry. In 120 minutes of radiation, the process of photocatalysis reduced the initial concentration of the Coomassie Brilliant Blue dye in half.

Kinetics of Protein Modification Reactions: Analysis of Modification-Induced Protein Unfolding

1987 ◽  
Vol 1 (4) ◽  
pp. 289-299 ◽  
Author(s):  
Emmanuel T. Rakitzis
Keyword(s):  
Protein Modification ◽  
Protein Unfolding ◽  
Kinetics Of

scholarly journals Inhibition of Primary Photosynthesis in Desiccating Antarctic Lichens Differing in Their Photobionts, Thallus Morphology, and Spectral Properties

2021 ◽  
Vol 9 (4) ◽  
pp. 818
Author(s):  
Miloš Barták ◽  
Josef Hájek ◽  
Alla Orekhova ◽  
Johana Villagra ◽  
Catalina Marín ◽  
...  
Keyword(s):  
Spectral Reflectance ◽  
Quantum Yields ◽  
Specific Response ◽  
Variable Fluorescence ◽  
Protective Mechanisms ◽  
Quenching Analysis ◽  
Relative Water ◽  
Species Specific ◽  
Kinetics Of ◽  
Reflectance Data

Five macrolichens of different thallus morphology from Antarctica (King George Island) were used for this ecophysiological study. The effect of thallus desiccation on primary photosynthetic processes was examined. We investigated the lichens’ responses to the relative water content (RWC) in their thalli during the transition from a wet (RWC of 100%) to a dry state (RWC of 0%). The slow Kautsky kinetics of chlorophyll fluorescence (ChlF) that was recorded during controlled dehydration (RWC decreased from 100 to 0%) and supplemented with a quenching analysis revealed a polyphasic species-specific response of variable fluorescence. The changes in ChlF at a steady state (Fs), potential and effective quantum yields of photosystem II (FV/FM, ΦPSII), and nonphotochemical quenching (NPQ) reflected a desiccation-induced inhibition of the photosynthetic processes. The dehydration-dependent fall in FV/FM and ΦPSII was species-specific, starting at an RWC range of 22–32%. The critical RWC for ΦPSII was below 5%. The changes indicated the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts at RWCs of below 20%. In both the wet and dry states, the spectral reflectance curves (SRC) (wavelength 400–800 nm) and indices (NDVI, PRI) of the studied lichen species were measured. Black Himantormia lugubris showed no difference in the SRCs between wet and dry state. Other lichens showed a higher reflectance in the dry state compared to the wet state. The lichen morphology and anatomy data, together with the ChlF and spectral reflectance data, are discussed in relation to its potential for ecophysiological studies in Antarctic lichens.

Synthesis and Photochromic Properties of 1-(2-methyl-1-phenyl)-2-[2-methyl-5-(4-formylphenyl)-3-thienyl]perfluoroyclopentene

2014 ◽  
Vol 886 ◽  
pp. 183-186
Author(s):  
Xiao Dong Zhang ◽  
Sha Sha Wei ◽  
Shou Zhi Pu
Keyword(s):  
Visible Light ◽  
Uv Light ◽  
Light Irradiation ◽  
Photochromic Properties ◽  
Kinetics Of

An unsymmetrical photochromic diarylethene 1-(2-methyl-1-phenyl)-2-[2-methyl-5-(4-formylphenyl)-3-thienyperfluoroyclopentene (1o) was designed and constructed successfully. Its photochromic properties were examined. The results showed that the compound exhibits good photochromism with UV/Vis light irradiation. The diarylethene 1o changed the color from colorless to blueviolet upon irradiation with 297 nm UV light, in which absorption maxima were observed at 549 and 581nm in hexane and PMMA films, respectively.The photochromic cyclization/cycloreversion kinetics of 1o in hexane were determined by UV-Vis spectra upon alternating irradiation with UV and appropriate wavelength visible light.

scholarly journals Synthesis of New Antibiotics Derivatives by the Photocatalytic Method: A Screening Research

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1102
Author(s):  
Wojciech Baran ◽  
Ewa Masternak ◽  
Dominika Sapińska ◽  
Andrzej Sobczak ◽  
Ewa Adamek
Keyword(s):  
Quantum Yield ◽  
Biologically Active ◽  
Quantum Yields ◽  
Photocatalytic Process ◽  
Experimental Conditions ◽  
New Antibiotics ◽  
Photocatalytic Reactions ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Uva Radiation

The aim of our study was to assess the possibility of using the photocatalytic process conducted in the presence of TiO2 to obtain new stable derivatives of antibacterial drugs. The possibility of introducing hydroxyl, chlorine, or bromide groups into antibiotics molecules was investigated. The experiments were conducted in aqueous solutions in the presence of TiO2-P25 as a photocatalyst, Cl− and Br- ions, and antibiotics belonging to eight different chemical classes. All experiments were initiated by UVa radiation. The kinetics of photocatalytic reactions and their quantum yield were determined, and the stable products were identified. All of the antibiotics used in the experiments underwent a photocatalytic transformation, and the quantum yields were in the range from 0.63 to 22.3%. The presence of Br- or FeCl3 significantly increased the efficiency of the photocatalytic process performed in the presence of TiO2, although Br- ion also acted as an inhibitor. Potentially biologically active chlorine derivatives from Trimethoprim, Metronidazole, Chloramphenicol, and bromine derivatives from Trimethoprim, Amoxicillin were obtained under experimental conditions. The potentially inactive halogen derivatives of Sulfamethoxazole and hydroxyl derivatives described in the literature were also identified.

Measurement of the Kinetics of Protein Unfolding in Viscous Systems and Implications for Protein Stability in Freeze-Drying

2005 ◽  
Vol 22 (7) ◽  
pp. 1176-1185 ◽  
Author(s):  
Xiaolin (Charlie) Tang ◽  
Michael J. Pikal
Keyword(s):  
Protein Stability ◽  
Freeze Drying ◽  
Protein Unfolding ◽  
Kinetics Of

Quantum Dots CdSe/ZnS-Loaded Poly(D,L-Lactide-Co-Glycolide) Nanoparticles: Physicochemical Characterization and Application

2006 ◽  
Vol 505-507 ◽  
pp. 667-672 ◽  
Author(s):  
Chih Hui Yang ◽  
Kuo Chin Lin ◽  
Yu Huai Chang ◽  
Yu Cheng Lin
Keyword(s):  
Quantum Dots ◽  
Fluorescence Intensity ◽  
Fluorescence Spectra ◽  
Uv Light ◽  
Physicochemical Characterization ◽  
Plga Nanoparticles ◽  
Optimum Concentration ◽  
Cellular Internalization ◽  
Optimum Concentration Range

This paper described and characterized the quantum dots (QDs) with/without the polymeric PLGA applied in MC3T3E-1 delivery. Neat QDs were treated with various solvents, temperatures, exposure time and concentration to evaluate their stability and efficacy. We found that the intensity degree of fluorescence spectra (QDs) in different solvents follows the order: ether > THF > acetone > chloroform > methanol. Importantly, the QDs become inactive after 8-hr dissolution in the solvents of ether, THF or chloroform. According to this result, acetone and methanol are ideal solvents for QDs. The optimum concentration range of QDs in acetone is 5 to 10 mg/mL. We found that no obvious difference of fluorescence intensity was detected in QDs stored respectively at 4 °C, 24 °C and 44 °C (8-hour). When QDs were exposed to UV light (312 nm) for 2 hr, serious decay of fluorescence intensity was observed. In order to extend the application of QDs in medical areas, we encapsulated them in individual biocompatible poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles for in-vitro imaging of endocytosis in MC3T3E-1 cells. We demonstrated that the polymeric PLGA have the ability to permeate the cells for cellular internalization; the endocytotic activity could be enhanced by the polymeric QDs-encapsulated PLGA.

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