• ALGAE
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• v.20 no.2
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• pp.113-120
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• 2005

The freshwater blooms mainly blue-green algal blooms occur frequently in the lower Naktong River in summer, which provoke many socio-economical problems; therefore, the early detection of bloom events are demanding through the quantitative and qualitative analyses of blue green algal species. The in vivo fluorescence properties of cultured strains of Microcystis aeruginosa, M. viridis, M. wesenbergii, M. ichthyoblabe, Anabaena cylindrica, A. flos-aquae, and Synedra sp. were investigated. Wild phytoplankton communities of the lower Naktong River were also monitored at four stations in terms of their standing stocks, biomass and fluorescence properties compared with its absorption spectram. The 77K fluorescence emission spectra of each cultured strains normalized at 620 nm was very specific and enabled to detect of blue green algal biomass qualitatively and quantitatively. The relative chlorophyll a concentration determined by chlorophyll fluorescence analysis method showed significant relationship with chlorophyll a concentration determined by solvent extraction method ($R^2$ = 0.906), and the blue-green algal cell number determined by microscopic observation ($R^2$ = 0.588), which gives insight into applications to early detection of blue green algal bloom.

• 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.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.572-581
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• 2022

Objective : Compared to microscopes, exoscopes have advantages in field-depth, ergonomics, and educational value. Exoscopes are especially well-poised for adaptation into fluorescence-guided surgery (FGS) due to their excitation source, light path, and image processing capabilities. We evaluated the feasibility of near-infrared FGS using a 3-dimensional (3D), 4 K exoscope with near-infrared fluorescence imaging capability. We then compared it to the most sensitive, commercially-available near-infrared exoscope system (3D and 960 p). In-vitro and intraoperative comparisons were performed. Methods : Serial dilutions of indocyanine-green (1-2000 ㎍/mL) were imaged with the 3D, 4 K Olympus Orbeye (system 1) and the 3D, 960 p VisionSense Iridium (system 2). Near-infrared sensitivity was calculated using signal-to-background ratios (SBRs). In addition, three patients with brain tumors were administered indocyanine-green and imaged with system 1, with two also imaged with system 2 for comparison. Results : Systems 1 and 2 detected near-infrared fluorescence from indocyanine green concentrations of >250 ㎍/L and >31.3 ㎍/L, respectively. Intraoperatively, system 1 visualized strong near-infrared fluorescence from two, strongly gadolinium-enhancing meningiomas (SBR=2.4, 1.7). The high-resolution, bright images were sufficient for the surgeon to appreciate the underlying anatomy in the near-infrared mode. However, system 1 was not able to visualize fluorescence from a weakly-enhancing intraparenchymal metastasis. In contrast, system 2 successfully visualized both the meningioma and the metastasis but lacked high resolution stereopsis. Conclusion : Three-dimensional exoscope systems provide an alternative visualization platform for both standard microsurgery and near-infrared fluorescent guided surgery. However, when tumor fluorescence is weak (i.e., low fluorophore uptake, deep tumors), highly sensitive near-infrared visualization systems may be required.

• KSBB Journal
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• v.14 no.3
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• pp.377-379
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• 1999

In order to improve the transfection efficiency of CHO/dhfr- cells using cationic lipid, optimal concentrations of the cationic lipid($LipofectAmine^{TM}$) and DNA(pEGFP-C1) need to be determined. The use of green fluorescent protein(GFP) gene as a reporter gene facilitated the quantification of transfection efficiency. The green fluorescence intensity of each cell transfected at various lipid-DNA concentrations was measured using fluorescence-activated cell sorter(FACS) analysis. A combination of $2.0{\mu}L$ cationic lipid and 0.4{$\mu}g$ DNA in a well resulted in the highest trasfection efficiency. Taken together, the method using FACS analysis of GFP is simple and fast, facilitating the optimization of transfection.

• Current Optics and Photonics
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• v.5 no.5
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• pp.554-561
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• 2021

Indocyanine green (ICG) is a cyanine dye that has been used in medical diagnostics based on fluorescence imaging, and in medical therapy based on the photothermal effect. It is important to systematically understand the photothermal effect and fluorescence characteristics of ICG simultaneously. By varying a number of conditions such as laser power density, laser irradiation wavelength, concentration of ICG solution, and exposure time of laser irradiation, the intensity properties of fluorescence and the temperature change induced by the photothermal effect are measured simultaneously using a charge-coupled-device camera and a thermal-imaging camera. The optimal conditions for maximizing the photothermal effect are determined, while maintaining a relatively long lifetime and high efficiency of the fluorescence for fluorescence imaging. When the concentration of ICG is approximately 50 ㎍/ml and the laser power density exceeds 1.5 W/cm², the fluorescence lifetime is the longest and the temperature induced by the photothermal effect rapidly increases, exceeding the critical temperature sufficient to damage human cells and tissues. The findings provide useful insight into the realization of effective photothermal therapy, while also specifying the site to be treated and enabling real-time treatment monitoring.

• Korean Journal of Optics and Photonics
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• v.35 no.1
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• pp.30-34
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• 2024

We report a purely protein-based platform for green fluorescence by mixing silk protein with green fluorescence protein, and also report its enhancement by the incorporation of TiO₂ nanoparticles. The TiO₂ nanoparticles employed have diameters of 100 and 300 nm, with a significant increase in fluorescence (by a factor of 7.5) observed when introducing 300-nm TiO₂ nanoparticles. Furthermore, an increase in particle distribution density is found to enhance fluorescence amplification. These research findings suggest that protein-based fluorescent films can be enhanced by the characteristics of nanoparticles, opening up new possibilities in the fields of optics and fluorescence applications.

• Journal of Korea Multimedia Society
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• v.22 no.12
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• pp.1339-1346
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• 2019

In the characteristic of the brain malignant, the blood vessels and tumors have the same color and shape, and the boundary distinction is not clear, Therefore, it is difficult to observe the naked eye. Because of the high invasiveness, the risk of recurrence is high. Therefore, complete resection of the tumor is essential. The method for distinguishing the boundary between blood vessels and tumors is a fluorescence contrast method using indocyanine green (ICG), a fluorescence contrast agent. In ICG, the concentration range analysis is very important because the fluorescence expression state varies depending on the concentration. However, since the analysis result of the fluorescence expression condition is insufficient according to the current concentration, this paper proposes by analyzing the initial protocol of the concentration range. 780 nm infrared light was irradiated to the ICG sample to observe the fluorescence expression through a near infrared (NIR) camera. The wavelength is measured by using a spectrum instrument (ocean view) to observe the fluorescence expression wavelength of 811nm. As a result of analyzing the mol concentration according to each sample, the fluorescence expression range was found to be 16.15-0.16M and the optimum fluorescence concentration on the brightest part was found to be 3.23-0.81M.

• 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.

• Medical Lasers
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• v.10 no.3
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• pp.123-131
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• 2021

Optical imaging modalities with properties of real-time, non-invasive, in vivo, and high resolution for image-guided surgery have been widely studied. In this review, we introduce two optical imaging systems, that could be the core of image-guided surgery and introduce the system configuration, implementation, and operation methods. First, we introduce the optical coherence tomography (OCT) system implemented by our research group. This system is implemented based on a swept-source, and the system has an axial resolution of 11 ㎛ and a lateral resolution of 22 ㎛. Second, we introduce a fluorescence imaging system. The fluorescence imaging system was implemented based on the absorption and fluorescence wavelength of indocyanine green (ICG), with a light-emitting diode (LED) light source. To confirm the performance of the two imaging systems, human malignant melanoma cells were injected into BALB/c nude mice to create a xenograft model and using this, OCT images of cancer and pathological slide images were compared. In addition, in a mouse model, an intravenous injection of indocyanine green was used with a fluorescence imaging system to detect real-time images moving along blood vessels and to detect sentinel lymph nodes, which could be very important for cancer staging. Finally, polarization-sensitive OCT to find the boundaries of cancer in real-time and real-time image-guided surgery using a developed contrast agent and fluorescence imaging system were introduced.

• Journal of Veterinary Clinics
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• v.39 no.6
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• pp.395-399
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• 2022

A 6-year-old spayed, female golden retriever dog was presented with a skin mass on the dorsal region of the right carpus. The cytology result of the region revealed characteristics of mast cell tumors (MCTs). Short wave-infrared fluorescence-guided surgery using Indocyanine green (ICG) was performed to determine the surgical margin of the tumor. ICG was injected intravenously 24 hours before the surgery and the patient was hospitalized and carefully monitored. During the surgery, ICG fluorescence-based surgery was performed to identify the tumor and the surgical margin. The tumor was visible, and the skin mass was resected using NIR device for the guidance of the surgical margin of the tumor. Once the resection was complete, the surgical site was again inspected with SWIR fluorescence imaging to identify residual tumor cells. The resected tumor, using ICG navigation, was classified as low-grade cutaneous MCT and the margin was complete on the histopathological result. We report herein a case of resection of a cutaneous MCT in a dog using SWIR fluorescence imaging ICG which can be potentially used for the identification of tumors and evaluation of the surgical margin for complete resection.