• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.413-417
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• 2005

Fluorescence of green fluorescent protein mutant, 2-5 GFP is observed during denaturation by guanidine. The fluorescence intensity decreases exponentially but the fluorescence lifetime does not change during denaturation. The fluorescence lifetime of the denatured protein is shorter than that of native form. As the protein structure is modified by guanidine, solvent water molecules penetrate into the protein barrel and protonate the chromophore to quench fluorescence. Most fluorescence quenchers do not affect the fluorescence of native form but accelerate the fluorescence intensity decay during denaturation. Based on the observations, a simple model is suggested for the structural change of the protein molecule during denaturation.

• Korean Journal Plant Pathology
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• v.11 no.2
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• pp.101-106
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• 1995

Deep blue fluorescence of resorcin blue-stained callose was observed only in the potato leafroll virus (PLRV)-infected potato plants, but not in other potato viruses investigated. The plant sections stained with aniline blue showed non-specific fluorescence regardless of PLRV infection, which means that aniline blue is not suitable for the staining of callose induces by PLRV infection. The fluorescence of resorcin blue-stained callose was more easily detectable than autofluorescence by a direct fluorescence detection method because of its deep blue color. The lateral branch of lower leaves was turned out to be the best material for fluorescence observation of all plant parts tested. In comparison of diagnostic efficacy of this technique to enzyme-linked immunosorbent assay (ELISA), PLRV infected potato plants showed corresponding increment of the fluorescence of resorcin blue stained callose as absorption values in ELISA increased. In the future, the criteria measuring the fluorescence objectively are thought to be determined for the practical application to the diagnosis of potato leafroll disease.

• Bulletin of the Korean Chemical Society
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• v.20 no.7
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• pp.796-800
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• 1999

Three anthrylazacrown ethers in which the anthracene fluorophore π system is separated from the electron donor atoms by one methylene group were synthesized, and their photophysical study was accomplished. These fluorescent compounds showed a maximum fluorescence intensity at pH=5 in aqueous solutions and a decrease in fluorescence intensity upon binding of paramagnetic metal cations (Mn 2+ (d 5 ), Co 2+ (d 7 ), Cu 2+ (d 9 )). The decrease in fluorescence intensity may be attributed to the paramagnetic effect of metal cations to deactivate the excited state by the nonradiative quenching process. The benzylic nitrogen was found to play an important role in changing fluorescence intensity. From the observed linear Stern-Volmer plot and the fluorescence lifetime independence of the presence of metal ions, it was inferred that the chelation enhanced fluorescence quenching (CHEQ) mechanism in the system is a ground state static quenching process. Enhanced fluorescence was also observed when an excess Na + ion was added to the quenched aqueous solution, and it was attributed to cation displacement of a complexed fluorescence quencher.

• Ocean Science Journal
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• v.42 no.1
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• pp.49-59
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• 2007

Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyll-a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.15 no.1
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• pp.47-54
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• 2011

In traditional Korean medicine, inspection of the tongue is an important method of making medical diagnoses and determining prognosis. We surveyed the fluorescence characteristics of the tongue coat in the ultraviolet light. The tongue coat comprises micro-organisms, blood metabolites, leukocytes from periodontal pockets, large amounts of desquamated epithelial cells released from the oral mucosa and different nutrients. In the ultraviolet light tissues of the oral cavity generally emit weak red or green fluorescence, which is not easily seen by the human eye, but is readily detected. This fluorescence has been proved to be due to the production of porphyrins by oral micro-organisms. While the composition of motile micro-organisms on the dorsum of the tongue is not constant, variations also occur persistingly in the fluorescence characteristics of the tongue coat. But because live bacteria contain a variety of intracellular biomolecules that have specific excitation and emission wavelength spectra characterizing their intrinsic fluorescence, the tongue coat emits fluorescence. the tongue itself, on the other hand, emits very weak or not fluorescence. In conclusion, we suggests that the uncoated tongue area be eliminated from the coated tongue area with the difference between the fluorescence characteristics of the tongue and that of the tongue coat.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.475-477
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• 1997

We have analyzed the fluorescence image obtaining from green fluorescence protein (GFP). In order to monitor the fluorescence of specific gene, we used the amyloid precursor protein promoter which has been known to act as a major role in the development of Alzheimer's disease. The promoter from - 3.0 kb to + 100 base pair was inserted into the gene expression monitoring GFP vector purchased from Clontech. This construct was transfected into the PC 12 and fibroblast cells and the fluorescence image was captured by two kinds of methods. One is using cheaper CCD camera and other is SIT-CCD camera. or the higher sensitivity of the fluorescence image, we developed the multiple image grabbing program. As a results, the fluorescence image by conventional CCD camera have the similar sensitivity compared with that of the SIT-camera by applying the multiple image grabbing programs. By this system. it will be possible to construct the fluorescence monitoring system with lower cost. And gene expression in real time by fluorescence image will be possible without changing the fluorescence images.

• Progress in Medical Physics
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• v.12 no.1
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• pp.79-94
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• 2001

The fluorescence emanating from a biological tissue contains information about scattering, absorption and the intrinsic fluorescence (fluorescence only due to fluorophores). Becaue fluorescence spectra of biological tissue are often significantly affected by the presence of tissue absorbers and scatterers, the measured tissue fluorescence cannot be interpreted as a linear combination of intrinsic fluorescence spectra of different tissue biochemical. We conducted experiments to examine the influence of scattering and absorption on the experimentally measured fluorescence of a turbid medium such as biological tissue. Therefore, we acquired fluorescence and reflectance spectra of tissue phantoms with a wide range of scatterer and absorber concentrations. By applying a photon migration model, which uses the scattering and absorption information contained in reflectance spectra to remove their distortion also present in fluorescence spectra, we extract the intrinsic fluorescence of these tissue models. We achieved excellent agreement between modeled and actual intrinsic fluorescence spectra. The motivation for this research is that intrinsic fluorescence spectra are expected to change with progression of disease in human tissue, due to changes in the tissue biochemical composition. It is not possible to distinguish the two tissue types by using only the measured fluorescence, however clear separation can be achieved with the intrinsic fluorescence in real time optical biopsy.

• Macromolecular Research
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• v.12 no.3
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• pp.282-289
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• 2004

We have extensively characterized the fluorescence behavior of unsaturated polyester (UP) resin in the absence and presence of a 1,3-bis-(l-pyrenyl)propane (BPP) fluorescent probe at various dynamic and isothermal cure histories by means of a steady-state fluorescence technique using a front-face illumination equipment. In addition, we explored the effect of the fluorescence intensity on the relaxation of the fluorescent probe in the UP resin by resting the dynamically and isothermally cured resin at ambient temperature and pressure for 24 h. The monomer fluorescence intensity, which has two characteristic peaks at 376 and 396nm, changed noticeably depending on the cure temperature and time and provided important information with respect to the molecular and photophysical responses upon curing. The result of the fluorescence study indicates that the increased local viscosity and restricted molecular mobility of the UP resin surrounding the BPP probe after curing are both responsible for the enhancement of the monomer fluorescence intensity. Our results also demonstrate that once the BPP probe has enough time to rearrange and become isolated prior to fluorescence, a sufficient amount of fluorescence is emitted. Therefore, we note that the fluorescence behavior of this UP resin system is influenced strongly by the relaxation process of the fluorescent probe in the resin as well as process used to cure the resin.

• Journal of Biosystems Engineering
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• v.34 no.1
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• pp.37-43
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• 2009

Hyperspectral reflectance and fluorescence scattering have been researched recently for measuring fruit post-harvest quality and condition. And they are promising for nondestructive detection of fruit quality. The objective of this research was to develop a model, which measure the quality of apple by using hyperspectral reflectance and fluorescence. A violet laser (408 nm) and a quartz tungsten halogen light were used as light sources for generating laser induced fluorescence and reflectance scattering in apples, respectively. The laser induced fluorescence and reflectance of 'Golden Delicious' apples were measured by using a hyperspectral imaging system. Fruit firmness, soluble solids and acid content were measured using standard destructive methods. Principal component analyses were performed to extract critical information from both hyperspectral reflectance and fluorescence data and this information was then related to fruit quality indexes. The fluorescence models had poorer predictions of the three quality indexes than the reflectance models. However, the prediction models of integrating fluorescence and reflectance performed consistently better than the individual models of either reflectance or fluorescence. The correlation coefficient for fruit firmness, soluble solid content, and tillable acidity from the integrated model was 0.86, 0.75, and 0.66 respectively. Also the standard errors were 6.97 N, 1.05%, and 0.07% respectively.

• Journal of Biosystems Engineering
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• v.35 no.2
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• pp.124-131
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• 2010

Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research has demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.