• Title/Summary/Keyword: Temperature Sensitive Fluorescence

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Temperature-sensitive Liposomes Modified with Poly(N-isopropylacrylamide-co-acrylamide) (Poly(N-isopropylacrylamide-co-acrylamide)로 변형된 온도민감성 리포좀)

  • Hee Dong Han;Sung Soo Kim;Ho Suk Choi;Byung Cheol Shin
    • Journal of the Korean Chemical Society
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    • v.47 no.3
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    • pp.257-264
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    • 2003
  • This study has investigated the temperature-sensitive liposomes, which release anticancer drug(doxorubicin) at the hyperthermia temperature$(~40^{\circ}C)$. The temperature-sensitive liposomes were modified with a copolymers of N-isopropylacrylamide(NIPAAm) and acrylamide(AAm), which exhibit a lower critical solution temperature (LCST) at the hyperthermia temperature. The release of doxorubicin from the modified liposomes was determined by measuring the fluorescence intensity with changing temperature and time. The release of doxorubicin from liposomes modified with poly(NIPAAm-co-AAm) copolymer was increased significantly, because poly(NIPAAm-co-AAm) could undergo the conformational transition in the narrow hyperthermia temperature region$(~40{\pm}2^{\circ}C)$. Moreover, we observed that doxorubicin released from liposomes within 5 minutes, and the size of modified liposomes was 120~170 nm. In this study, we have prepared temperature-sensitive liposomes which could be controlled by temperature. They can be applied in the field of a drug delivery system for tumor targeting by temperature control.

Determination of Glyphosate in Whole Blood by HPLC-fluorescence Detection (HPLC 형광검출법에 의한 Glyphosate의 혈중농도 측정)

  • 이상기;김기욱;양자열;인상환;이수연
    • YAKHAK HOEJI
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    • v.45 no.4
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    • pp.347-351
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    • 2001
  • A rapid and sensitive method for the determination of glyphosate, a phosphated amino acid herbicide, in whole blood is presented. After removal of protein, the whale blood was purified by using the anion exchange resin (Dowex 1), and derivatized with 9-fluorenylmethyl chloroformate (FMCL). Derivatized glyphosate from blood sample was injected onto a Whatman partisil 10SAX column and separated with 0.1M phosphate buffer (pH 2.5) and acetonitrile (ratio=3:1). The high performance liquid chromatography-fluorescence detection gave the detection limit of 86pg and linearity of 0.9999 in the range of 0.25 $\mu$g/ml and 25 $\mu$g/ml. The recoveries of glyphosate added to the blood samples were ranged from 75.3% to 100.4% compared to the samples prepared in water. The derivatized glyphosate was stable at various acidity and temperature. This method has been successfully applied to the blood samples of lethal intoxication with the herbicide glyphosate.

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Studies on the Fluorophotometric Determination of Gentamicin Sulfate and its Preparations (Gentamicin Sulfate의 형광분석법에 관한 연구)

  • 백우현;김정우;허명권;박근창
    • YAKHAK HOEJI
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    • v.22 no.1
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    • pp.15-21
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    • 1978
  • Gentamicin sulfate reacted with pyridoxal and zinc (II) ion in pyridine-methanol solution to yield highly fluorescent zinc(II) chelates of N-pyridoxylidene derivatives. This fluorescence reaction was sensitive and showed excitation maximum at 398nm, and emission maximum at 482nm. The effects of reagent concentration, reaction time and temperature, standing time and temperature were studied. And a new fluorophotometric method for the determination of gentamicin sulfate was developed. A good result was obtained and this method was applied to various preparations.

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Differential Recovery of Photosystem II Complex from Low-Temperature Photoinhibition in Plants with Different Chilling Sensitivity

  • Moon, Byoung-Yong;Norio Murata
    • Journal of Photoscience
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    • v.7 no.2
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    • pp.39-44
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    • 2000
  • To examine the chilling tolerance lipids, we compared the chilling susceptibility of photosystem II of wild type tobacco plants with that of transgenic tobacco plants, in which the sensitivity to chilling had been enhanced by genetic modification of fatty acid unsaturation of chloroplast membrane lipids. The transgenic tobacco plants were found to contain reduced levels of unsaturated membrane fatty acids by being tansformed with cDNA for glycerol-3-phosphate acyltransferase from squash. For the purpose of studying on the functional integrity of photosystem II during low-temperature photoinhibition, the photochemical efficiency was measured as the ration of the maximun fluorescence of chlorophyll (Fv/Fm) of photosystem II. In parallel with an investigation on the transgenic plants, susceptibility of chilling-resistant species, such as spinah and pea, and of chilling-sensitive ones, such as squash and sweet potato, to low-temperature photoinhibition was also compared in terms of room temperature-induced chlorophyll fluorescence from photosystem II. When leaf disks from the two genotypes of tobacco plants were exposed to light at 5$^{\circ}C$, the transgenic plants showed more rapid decline in photochemical activity of photosysytme II than wild-type plants. When they were pretreated with lincomycin, an inhibitor of chloroplast-encoded protein synthesis, the extent of photoinhibition was even more accelerated. More impottantly, they showed a comparable extent of photoinhibition in the presence of lincomycin, making a clear contrast to the discrepancy observed in the discrepancy observed in the absence of lincomycin. Restoration of Fv/Fm during recovery from low-temperature photoinhibition occurred more slowly in the transgenic tobacco plants than the wild-type. These findings are discussed in relation to fatty acid unsaturation of membrane phosphatidylglycerol. It appears that the ability of plants to rapidly regenerate the active photosystem II complex from might explain, in part, why chilling-resistant plants can toleratlow-temperature photoinhibition.

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Synthesis and pH-Dependent Micellization of a Novel Block Copolymer Containing s- Triazine Linkage

  • Pal Ravindra R.;Lee Doo Sung
    • Macromolecular Research
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    • v.13 no.5
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    • pp.373-384
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    • 2005
  • Novel pH-sensitive moieties containing an s-triazine ring were synthesized with sulfonamide and secondary amino groups. The synthesized pH-sensitive moieties were used for the synthesis of a pH-sensitive amphiphilic ABA triblock copolymer. The pH-sensitive triblock copolymer was composed of diblock copolymers, methoxy poly(ethylene glycol)-poly ($\varepsilon$-caprolactone-co-D,L-lactide) (MPEG-PCLA), and pH-sensitive moiety. These copolymers could be dissolved molecularly in both acidic and basic aqueous media at room temperature due to secondary amino and sulfonamide groups. The synthesized s-triazine rings containing pH-sensitive compounds were characterized by ${^1}H-NMR,\;{^13}C-NMR$, and LC/MSD spectral data. The synthesized diblock and triblock copolymers were also characterized by ${^1}H-NMR$ and GPC analyses. The critical micelle concentrations at various pH conditions were determined by fluorescence technique using pyrene as a probe. Furthermore, the micellization and demicellization study of the triblock copolymer was done with pH-sensitive groups. The sensitivity towards pH change was further established by acid-base titration.

Light-Dependent Chilling Injury on the Photosynthetic Activities of Cucumber Cotyledons (저온처리한 오이의 자엽에서 광합성 활성의 광의존성 저해)

  • 김현식
    • Journal of Plant Biology
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    • v.36 no.2
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    • pp.133-140
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    • 1993
  • The photosynthetic activities in relation to oxygen evolution rates, quantum yield, CO2 uptake rates and room temperature chlorophyll fluorescence were investigated in cotyledons of cucumber seedlings exposed to low temperature (at 4$^{\circ}C$) for 24 h. Light-chilling caused more inhibition on light-saturated maximum oxygen evolution rates, quantum yield, and CO2 uptake rates than dark-chilling did in the cucumber plant. Light-chilling induced more marked increase in Fo and decrease in (Fv)m/Fm than dark-chilling did in the room temperature chlorophyll induction kinetics. The above results affected by chilling in the light are considered to be associated with the partial damage of the reaction center of PS II and the decreased photosynthetic activities. There occurred a large decrease in qQ with little change in qNP in the light-chilling plant. When light- and dark-chilled plants were recovered at room temperature for 24 h and their chlorophyll fluorescences were induced with light doubling technique, light-chilled plants showed more smaller magnitude and rate of fluorescence relaxation than dark-chilled plants. These suggest that light-chilling might cause some alterations in transthylakoid pH formation, and that photosynthetic apparatus of cucumber cotyledons is more susceptible to light-chilling. In the fast fluorescence induction kinetics, FR was decreased by 60% in the light-chilled plants with reference to $25^{\circ}C$ light-grown plants, while the dark-chilled plants showed a decreased rate of only 20% with reference to $25^{\circ}C$ dark-treated plants for 24 h, indicating that cucumber seedling is very sensitive to chilling stress. So, it is certain that chilling injury to the photosynthetic apparatus is strongly dependent on the presence of light in cucumber seedlings.

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Effect of Soil Water and Shading Treatment on Chlorophyll Fluorescence Parameters and Photosynthetic Capacity in Cnidium officinale Makino (토양 수분 스트레스와 차광 처리가 천궁의 엽록소 형광반응 및 광합성에 미치는 영향)

  • Kim, Kwang Seop;Seo, Young Jin;Kim, Dong Chun;Nam, Hyo Hoon;Lee, Bu Yong;Kim, Jun hyung
    • Korean Journal of Medicinal Crop Science
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    • v.28 no.6
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    • pp.412-420
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    • 2020
  • Background: Measurement of chlorophyll fluorescence (CF) is useful for detection the ability of plants to tolerate environmental stresses such as drought, and excessive sunlight. Cnidium officinale Makino is highly sensitive to water stress and excessive sunlight. In this study, we evaluated the effect of soil water and shade treatment on the photosynthesis and leaf temperature change of C. officinale. Methods and Results: C. officinale was cultivated under uniform irrigation for 1 week drought stress (no watering) for 6 days. A significant decrease in CF was observed on the 5th day of withholding water (approximately 6% of soil water content) regardless of shading. Notably, the Rfd_lss parameter (CF decrease rates) with and without shade treatment was reduced by 73.1% and 56.5% respectively, at 6 days compared with those at the initial stage (0 day). The patterns of the degree of CF parameters corresponded to those of the soil water content and difference between leaf temperature (Ts) and air temperature (Ta). Meanwhile, CF parameters recovered to the 3 - 4 days levels after re-watering, while the soil water potential was completely restored. The suitable soil water content for C. officinale optimal growth was between -5 kPa and -10 kPa in this experiment. Conclusions: Lack of soil water in the cultivation of C. officinale, even with shading, decreased latent heat cooling through transpiration. As a result, heat dissipation declined, and the plant was subjected to drought stress. Soil water content plays a major role in photosynthesis and leaf temperature in C. officinale.

Remote Real-Time Uranium Concentration Measurement Using the Nitrogen Laser and optode (질소레이저와 광섬유를 이용한 원격제어 실시간 우라늄 농도 측정)

  • Lee, Sang-Mock;Shin, Jang-Soo;Lee, Su-Mi;Koh, Kwang-Nak;Kang, Shin-Won
    • Journal of Sensor Science and Technology
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    • v.6 no.5
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    • pp.362-368
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    • 1997
  • The remote real-time uranium concentration analysis using nitrogen laser, optode, photomultiplier and optical fiber is studied. The optode for the remote collection of uranium fluorescence is designed. The fluorescence intensity at time zero is calculated in order to exclude the quenching effect and the temperature fluctuation and used for more precise estimation. The fluorescence change is very sensitive to the uranium concentration change. The method shows the detection limit of 0.06ppm and the linearity between 0.1ppm and 2ppm of the aqueous uranium concentration.

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Cure Monitoring of Am Epoxy-Anhydride System by Means of Fluorescence Spectroscopy (형광분석기를 이용한 에폭시-산무수물계의 경화 모니터링)

  • 조동환;김득수;이종근
    • Polymer(Korea)
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    • v.25 no.2
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    • pp.199-207
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    • 2001
  • In the present study the cure behavior of diglycidyl ether of bisphenol-A(DGEBA) using an anhydride-based hardener in the presence of N,N-dimethyl benzyl amine (BDMA) or 1-cyanoethyl-2-ethyl-4-methyl imidazole (2E4MZ-CN) as an accelerator has been monitored and interpreted from the viewpoint of photophysical properties by means of fluorescence spectroscopy. To do this, 1,3-bis-(1-pyrene)propane (BPP) was well incorporated in the epoxy resin system by mechanical blending. The BPP probe, which is very sensitive to conformational change of the molecule influenced by the surrounding medium, successfully formed intramolecular excimer fluorescence. It is susceptible to the micro-viscosity or local viscosity and molecular mobility according to the epoxy cure. The cure behavior was explained with monomer fluorescence intensity ($I_{M}$ ), excimer fluorescence intensity ($I_{E}$ ) and $I_{M}$ /$I_{E}$ ratio as a function of cure time, cure temperature and accelerator. The present work agreed with the previous report on the cure behavior of an epoxy-anhydride system studied using DSC or torsion pendulum method. This study also suggests that the use of fluorescence technique may provide information on cure behavior of a thermosetting resin in a low temperature region, which has not been well interpreted by other analytical methods.

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Early Alterations of Chlorophyll Fluorescence by Light-Chilling in Cucumber (Cucumis sativus) Leaves and Their Usage as Stress Indicators (오이 잎에서 저온 광저해에 의한 형광유도과정의 초기 변이와 스트레스 지표)

  • Ha, Suk-Bong;Young-Jae Eu;Choon-Hwan Lee
    • The Korean Journal of Ecology
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    • v.19 no.2
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    • pp.151-163
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    • 1996
  • To investigate the early symptoms of light-chilling, alterations of chlorophyll fluorescence transients were monitored in cucumber (Cucumis sativus L. cv. Ilmichungjang) leaves. During 24 h chilling, decreases in (Fv)m/Fm, qE and qQ, and an increase in Fo were observed. The chilling effects were not recovered at room temperature, and a significant increase in Fo was observed during the recovery period. After 6 h chilling, ‘dip’(D) level of the transients became obscure, and the negative slope after ‘peak’(P) disappeared. The first derivative (dFv/dt) of the fast fluorescence rise curve was used to obtain more accurate information about the changes in the transients. The maximal rate of the fluorescence increase in the D-p rise curve (Fr) has been the most frequently used chilling stress indicator. However, a correct value of Fr could not be measured when the D level became obscure. This problem was overcome by introducing a new indicator, HFr (dFv/dt at Fv = 1/2 (Fv)m), and HFr gave very similar values to Fr. To monitor the changes in curvature around D level, another new parameter, ${\Delta}S$(D-Fr), was also introduced. These three parameters decreased very sensitively during light-chilling. In addition, increases in these parameters were observed during the first 2 h chilling, but this increase in Fr was also observed in pea leaf discs dark-chilled for 15 min, suggesting that this very early change is a common response to chilling in both pea and cucumber leaves. Quenching coefficients were also very sensitive to chilling, especially qE. Discussion on the usage of these parameters as chilling stress indicators is given in the text.

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