• Journal of the Microelectronics and Packaging Society
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• v.26 no.2
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• pp.59-64
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• 2019

In this paper, we introduced a near-infrared multi-channel fluorescence imaging system and analyzed the effects of measurements variables such as exposure time, working distance and intensity of excitation light. Fluorescence signal is increased as exposure time becomes longer, excitation light intensity increases or working distance becomes smaller. Furthermore, the proper composition of optical filters and precise packaging of the imaging modules prevent the increase of background signal. Thus, we confirmed an increase in SBR. Based on the result of this research, we proposed a method to use a multi-channel fluorescence imaging system.

• BMB Reports
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• v.30 no.4
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• pp.258-261
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• 1997

A simple quantitative assay method for ribonuclease activity has been developed. This method is based on the decrease of fluorescence intensity emitted by the ethidium bromide bound to RNA due to the degradation of RNA by ribonuclease. The substrate RNA was reacted with ribonuclease A and the fluorescence intensity was measured after the addition of ethidium bromide. The intensity difference was calculated using a blank reaction mixture containing no RNase. Whole cellular RNA substrate produced a significant error and was not suitable for this assay method possibly because of local microheterogeniety caused by high molecular weight rRNA. but satisfying results were obtained with tRNA substrate. The intensity difference increased linearly by raising enzyme concentration up to $2{\times}10^{-4}$ Kunitz Units of ribonuclease A. More refined and reliable results were obtained by use of initial reaction velocities which were calculated from the plots of intensity difference vs time. A linear relationship between initial velocities and enzyme concentrations was observed up to 0.01 Kunitz Units of enzyme.

• Korean Journal of Optics and Photonics
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• v.24 no.2
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• pp.71-76
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• 2013

Using fluorescence correlation spectroscopy, we analyzed the change of effective focal volume of a confocal system with light intensity. The fluorescence correlation spectroscopy system was home-built in accordance with the He-Ne laser with a wavelength of 632.8 nm, and two kinds of samples (AlexaFluor657 and Quantum dot655) suitable for the wavelength of the laser beam were used. For each sample, we analyzed and compared the correlation functions obtained while changing the intensity of the light source in a range of 1~50 ${\mu}W$. The result shows that the radius of the focal area increases linearly through the increase of particle number and diffusion time in response to an intensity change in weak light below 10 ${\mu}W$. In the higher intensity region (>10~15 ${\mu}W$), the increasing rate of particle number and diffusion time keep increasing but at a much slower rate. Through this result, it was also found that the radius increasing rate of the focal area was reduced however, the radius still increased slightly.

• Toxicological Research
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• v.34 no.1
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• pp.1-6
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• 2018

The purpose of this study was to detect cell death in the liver of mice treated with thioacetamide (TAA) using fluorescence bioimaging and compare this outcome with that using conventional histopathological examination. At 6 weeks of age, 24 mice were randomly divided into three groups: group 1 (G1), control group; group 2 (G2), fluorescence probe control group; group 3 (G3), TAA-treated group. G3 mice were treated with TAA. Twenty-two hours after TAA treatment, G2 and G3 mice were treated with Annexin-Vivo 750. Fluorescence in vivo bioimaging was performed by fluorescence molecular tomography at two hours after Annexin-Vivo 750 treatment, and fluorescence ex vivo bioimaging of the liver was performed. Liver damage was validated by histopathological examination. In vivo bioimaging showed that the fluorescence intensity was increased in the right upper part of G3 mice compared with that in G2 mice, whereas G1 mice showed no signal. Additionally ex vivo bioimaging showed that the fluorescence intensity was significantly increased in the livers of G3 mice compared with those in G1 or G2 mice (p < 0.05). Histopathological examination of the liver showed no cell death in G1 and G2 mice. However, in G3 mice, there was destruction of hepatocytes and increased cell death. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining confirmed many cell death features in the liver of G3 mice, whereas no pathological findings were observed in the liver of G1 and G2 mice. Taken together, fluorescence bioimaging in this study showed the detection of cell death and made it possible to quantify the level of cell death in male mice. The outcome was correlated with conventional biomedical examination. As it was difficult to differentiate histological location by fluorescent bioimaging, it is necessary to develop specific fluorescent dyes for monitoring hepatic disease progression and to exploit new bioimaging techniques without dye-labeling.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3055-3060
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• 2012

A simple, rapid and sensitive spectrofluorometric method was developed for the determination of folic acid (FA), based on its quenching effect on the fluorescence intensity of enoxacin (ENX)-europium ($Eu^{3+}$) complex as a fluorescent probe. Fluorometric interaction between ENX-$Eu^{3+}$ complex and FA was studied using UV-visible and fluorescence spectroscopy. The quenched fluorescence intensity at an emission wavelength of 614 nm was proportional to the concentration of FA. Optimum conditions for the determination of FA were investigated. Under optimal conditions, the reduced fluorescence intensity at 614 nm was responded linearly with the concentration of FA. The linearity was maintained in the range of $1.25{\times}10^{-9}$ to $1.50{\times}10^{-7}$ M (R = 0.9986) with the limit of detection ($3S_b/m$) (where $S_b$ is the standard deviation of blank and m is the slop of linear calibration curve) of $6.94{\times}10^{-10}$ M. The relative standard deviation (RSD) for 9 repeated measurements of $1.0{\times}10^{-9}$ M FA was 1.42%. This method was simple, cost effective, and relatively free of interference from coexisting substances. Successful determinations of FA in pharmaceutical formulation and biological samples with the developed method were demonstrated.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.275-280
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• 2014

Leucine-responsive Regulatory Protein (Lrp) from Escherichia coli is an 18.8 kDa protein composed of 164 amino acids. Wild type Lrp (Lrp Wt) does not possess any tryptophan amino acid which has strong intrinsic fluorescence, whereas the mutant Lrp R145W contains a single tryptophan at the position 145 in the leucine-responsive domain. To investigate the fluorescence character, the Lrp R145W and Lrp Wt proteins were purified. The fluorescence intensity of Lrp R145W is much higher than that of wild type protein, and the intensity of Lrp R145W was decreased by binding to its specific DNA designed from ilvIH operon and to L-leucine. In addition, the tryptophan fluorescence intensity of Lrp R145W was strongly quenched by addition of acrylamide even in the least amount of concentration as well as by urea. The data obtained from this study may give valuable information on the three dimensional structure of Lrp R145W.

• Korean Journal of Veterinary Research
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• v.30 no.1
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• pp.41-49
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• 1990

These experiments were carried out to develop a novel, simple, and rapid method to determine urinary sulfonamides using fluorescamine by spectrofluorometry. To get optimal conditions for the sulfonamide-fluorescamine reaction, sulfonamides such as sulfamethazine, sulfamerazine, sulfadimethoxine and sulfamonomethoxine, dissolved in buffers with various pH ranges were reacted with various concentrations of fluorescamine. and then, the fluorescence intensity and stability of the fluorophore were measured. To eliminate the interfering substances in urine, the fluorophore in buffers and urine with a definite pH range was extracted with some organic solvents. After then the fluorescence intensity was measured in organic and aquous phases. The results obtained were summarized as follows: 1. The maximal fluorescence of sulfonamides was presented in acidic state, pH 4.5~5.0, at 30 minutes after reaction. 2. The optimal concentration ratio of sulfamethazine and ffuorescamine was more than 1 : 40 in mole. 3. In pH 4.0, the intensity was maximal but was time-dependent, whereas in pH 8.0, the intensity was time-independent. 4. Sulfamethazine-fluorescamine conjugate could be dissolved in some of organic solvents in acidic state such as chloroform, n-butanol, and ethylacetate. 5. Sulfamethazine-flnorescamine conjugate in swine urine coule be extracted with ethylacetate in acidic state, pH 4.0~5.0.

• The Journal of the Korean dental association
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• v.57 no.4
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• pp.213-220
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• 2019

Purpose: The aim of this study was to evaluate the red fluorescence characteristics of bacterial dental deposits assessed by quantitative light-induced fluorescence (QLF) technology and confirm whether the red fluorescence can distinguish and evaluate quantitatively accumulation of bacterial dental deposits. Methods: This retrospective cross-sectional study used QLF images captured at a dental clinic from January to December 2016. In each QLF image, a skilled examiner selected one region where the presence of deposits was suspected. Then, the regions were classified into three groups of not detectable deposits(ND), half detectable deposits (HD), and full detectable deposits (FD) by two examiners according to classification criteria. Only those images where the regions of bacterial dental deposits were classified identically by all examiners were used for analysis. The mean red fluorescence intensity (RFI) was defined as the mean value of R/G for all pixels in the regions. The RFI was compared between groups using Welch's ANOVA test, and the Spearman correlation was calculated to assess the association between RFI and accumulation of deposits. Results: In this study, 351 images among the collected images of 605 subjects were finally selected. The mean age of subjects was about 44 years. The R/G values of the ND, HD and FD were 0.73, 1.26 and 1.83 respectively. There were significant differences between all groups (p<0.001), and strong positive correlation was identified between the R/G value and the accumulation of deposits (r = 0.90, p<0.001). Conclusion: The intensity of red fluorescence as observed in the QLF images correlated well with the accumulation maturation of the deposits, which indicates that the QLF technology can be used to evaluate the status of oral hygiene.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 1997.06a
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• pp.94-94
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• 1997

• Journal of Integrative Natural Science
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• v.3 no.1
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• pp.28-32
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• 2010

Thiophene-derivatized pentiptycenes were synthesized and characterized by NMR and UV-Vis spectroscopy. Aggregation behavior of thiophene-derivatized pentiptycenes was monitored by the measurement of fluorescence. Fluorescence intensities for the thiophene-derivatized pentiptycenes and thiophene-derivatized pentiptycenes aggregates were compared. There is no shift in the maximum of the emission wavelength. In the range of water fraction between 20% and 40%, the emission intensity of thiophene-derivatized pentiptycene aggregates remains almost identical. Fluorescence efficiency incresaed by about 5 times higher when the thiophene-derivatized pentiptycenes forms the aggregates in solution.