• Toxicological Research
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• v.7 no.1
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• pp.29-35
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• 1991

Barbiturates are commonly abused tranquilizer and a rapid method to determine these drugs in biological samples is needed. In this study, was screened barbiturates in urine specimens by the fluorescence polarization immunoassay method(FPIA) and the positive samples were confirmed and identified by the more definitive GC/MS method. Fifteen positive smples which have barbiturate values higher than 0.5 ng/ml were analyzed by the GC/MS method. Eight samples were identified as phenobarbital and five samples were identified as crotilbarbitone.

• Journal of fish pathology
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• v.19 no.1
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• pp.83-86
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• 2006

Effect of iron on the extracellular proteolytic activity of live Uronema marium was determined by fluorescence polarization (FP) method. Supplementation of 0.5 and 5.0 μM iron significantly increased caseinolytic activity of live U. marinum. In contrast, supplementation of 50 μM iron showed no significant differences in FP values compared to the control. The present result suggests that iron in cultured water or skin tissue of olive flounder may influence on the penetration and establishment of U. marinum, correlating with modulation of extracellular protease activity of the ciliates.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.943-947
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• 2008

A phosphate-specific and fluorescent probe was prepared for label-free phosphatase assays based on fluorescence polarization. By using the probe, dephosphorylation reactions of DNA and protein substrates by calf intestinal alkaline phosphatase (CIP) could effectively be monitored in real-time. Since this assay method does not require additional materials such as labeled substrates and phosphospecific antibodies to obtain fluorescence polarization signals, it is simple, cost-effective, and expected to be useful not only for measuring activity of phosphatases but also for high-throughput screening of phosphatase inhibitors.

• YAKHAK HOEJI
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• v.38 no.2
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• pp.131-139
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• 1994

Calcein-encapsulated small unilamellar vesicles of various lipid composition were prepared using the sonication technique, and their stabilities at $20^{\circ}C$ were examined by measuring calcein leakage from the liposomes. The fluidity of these liposomal bilayers was also investigated by measuring the fluorescence polarization of DPH labelled into the liposomes. The results showed that liposomes made of PC mixtures with different acyl chain length were very stable, which may be due to the formation of interdigitated bilayer structure. The addition of cholesterol further stabilized these PC liposomes. However, addition of cholesterol reduced the encapsulation efficiences of liposomes. The fluidity of the liposomes was significantly decreased by cholesterol in the liquid crystalline state, but not changed in the gel state. These results suggest that the enhanced stability of PC mixture liposomes may be ascribed to the formation of stable interdigitated bilayer structure. In membrane-mimetic and drug-delivery studies, vesicles made of mixtures of various phospholipids are recommended instead of addition of cholesterol to the phospholipid.

• Toxicological Research
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• v.7 no.1
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• pp.21-27
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• 1991

We developed a simple method to determine benzodiazepines in biological samples using electron capature detectors and nitrogen-phosphorous detectors. The extraction of 13 benezodiazepines in urine at pH 9.5 with toluene and its analysis in GC/NPD showed the peaks in 9-16 min. In this retention time range, the biological backaground was fairly low and the drugs could be identified in low concentrations. The benzodiazepines in urine samples were screened by the fluorescence polarization immunoassay and positive samples were confirmed by the GC/NPD method.

• Journal of Photoscience
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• v.12 no.3
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• pp.119-122
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• 2005

The photophysical properties of coumarin 6 laser dye have been studied in two solvents; ethanol and acetonitrile using steady-state fluorescence depolarization technique. The experimentally measured reorientation time of coumarin 6 is more or less the same in given solvents at particular temperature. It is found that coumarin 6 rotates slower in acetonitrile than in ethanol especially at higher values of viscosity over temperature. We also measure the ground and excited state dipole moments of coumarin 6 by solvent perturbation method. The results found that excited state dipole moment is greater than ground state dipole moment, which indicates that excited state is more polar than the ground state.

• Journal of Life Science
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• v.16 no.6
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• pp.1006-1013
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• 2006

To High Throughput Screening (HTS), a homogeneous fluorescence polarization immunoassay (FPIA) was developed for the quantitative determination of ochratoxin A(OTA) using a $Victor^3$ (PerkinElmer). The homologous tracer, fluorescein-labelled OTA-EDF were synthesized and a specific OTA antibody has been used in the development of the method. It allowed the determination of OTA in the concentration range 0.5-200 ng/ml, with the detection limit of 0.3 ng/ml. The method developed was highly specific and reproducible. OTA spikes in unpolished rice extracts were determinable by FPIA with good recovery. For naturally contaminated unpolished rice samples some disagreement was observed between the results obtained by FPIA and HPLC, which could be related to the a little matrix effect observed for FPIA. Further research is needed to validate the procedure. On the basis of these initial results, this FPIA appears to meet the performance criteria for OTA screening of food samples without a complicated clean-up.

• Current Optics and Photonics
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• v.8 no.4
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• pp.421-426
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• 2024

The use of stimulated emission depletion (STED) microscopy has significantly improved resolution beyond the limits imposed by diffraction; Furthermore, STED microscopy adopts a 4Pi-geometry to achieve an isotropic improvement in resolution. In isoSTED microscopy, a polarizing beam splitter and retarders are used in a 4Pi cavity to split beams of identical power, generating constructive and destructive interference for lateral and axial resolution improvements, respectively. The precise alignment of the retarders is crucial for optimizing the performance of isoSTED microscopy, because this orientation affects the quality of the depletion focus, necessitating zero intensity at the center. Incomplete destructive interference can lead to unwanted fluorescence inhibition, resulting in degraded resolution and contrast. However, measuring the intensity and polarization state in each optical path of the 4Pi cavity is complex and requires additional devices such as a power meter. Here, we propose a simple and accurate alignment method for the 4Pi cavity in isoSTED microscopy. Our approach demonstrates the equal allocation of power between upper and lower beam paths and achieves complete destructive interference using a polarizing beam displacer and a single CCD camera positioned outside the 4Pi cavity.

• Journal of Integrative Natural Science
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• v.5 no.3
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• pp.163-167
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• 2012

UV spectrophotometer was used to detect protein-DNA complex from DNA melting profile under constant temperature increase. Melting temperature (Tm) was $43^{\circ}C$ in copA duplex DNA alone. In the presence of Proteus mirabilis transcription regulator protein (PMTR) protein at 0.2 and 0.4 ${\mu}M$, Tm's were $45{\pm}0.5$ and $47.6{\pm}0.6^{\circ}C$, respectively. According to fluorescence polarization and gel shift assay. PMTR:copA complex was detected by the retarded migration on gel and the dissociation constant ($K_d$) was $(9.2{\pm}2.8){\times}10^{-9}M$.

• Journal of the Korean Chemical Society
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• v.22 no.4
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• pp.239-244
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• 1978

Spectroscopic studies of trans-1,2-bispyrazylethylene (BPE), one of the stilbene analogues, were carried out. In normal UV spectra, a distinct $n{\rightarrow}{\pi}^*$ absorption band is missing because of a strong, nearly isoenergetic ${\pi}{\rightarrow}{\pi}^*$ absorption band. The second derivative and low temperature $(77^{\circ}K)$ UV absorption spectra were taken and $n{\rightarrow}{\pi}^*$ absorption band was identified by these methods. The transition energies of ${\pi}{\rightarrow}{\pi}^*$ transitions were calculated by Pariser-Parr-Pople (PPP)-SCF-CI MO method. The calculated values showed good agreement with the observed spectral data. Luminescence studies were also carried out at low temperature. From the fluorescence spectra, fluorescence polarization studies, and PPP-SCF-CI MO calculation, the fluorescent state was determined to be a singlet $({\pi},\;{\pi}^*)$ state. This conclusion is in good agreement with the results obtained from alkaline salt effects on the fluorescence of this compound.