• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4165-4168
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• 2012

Magnetic fluorescent silica nanotubes were fabricated using reverse micro-emulsions coupled with conventional sol-gel methods. Anodic aluminum oxide templates were used to separate spatially the magnetic and the fluorescent moieties on individual nanotubes and so prevent quenching of the fluorescence. C18 and fluorescent layers were deposited sequentially on silica. Magnetism was then obtained by the introduction of pre-made magnetic nanoparticles inside the nanotubes. The photo- and chemical stabilities of nanotubes were demonstrated through dye release and photobleaching tests. The produced nanotubes did not show fluorescence quenching upon the addition of the nanoparticles, an advantage over conventional spherical fluorescent magnetic nanoparticles. High photostability of nanotubes, magnetism and biocompatiblily make them potentially useful in bioanalysis.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.1-7
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• 2016

The graphene oxides (GOs) were tested as a fluorescent quencher in the field of DNA-diagnostics. The various suspensions of GO nanoplates were prepared by changing the synthesis conditions. The suspensions were stable for at least 6 weeks by differing degrees of functionalization of various oxygen-containing groups of atoms. Depending on the properties of GO nanoplates, their fluorescent quenching abilities, which were determined by the amount of the tagged immobilized oligonucleotide, were also changed. GO suspension synthesized at $75^{\circ}C$ of reaction mixture showed the fluorescent quenching of 16.39 nmol/mg, which would be a potential substitution of molecular fluorescent quencher in test-systems for DNA-diagnostics.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.503-510
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• 2015

The iLOV protein belongs to a family of blue-light photoreceptor proteins containing a light-oxygen-voltage sensing domain with a noncovalently bound flavin mononucleotide (FMN) as its chromophore. Owing to advantages such as its small size, oxygen-independent nature, and pH stability, iLOV is an ideal candidate over other reporter fluorescent proteins such as GFP and DsRed. Here, for the first time, we describe the feasibility of applying LOV domain-based fluorescent iLOV as a metal sensor by measuring the fluorescence quenching of a protein with respect to the concentration of metal ions. In the present study, we demonstrated the inherent copper sensing property of the iLOV protein and identified the possible amino acids responsible for metal binding. The fluorescence quenching upon exposure to Cu²⁺ was highly sensitive and exhibited reversibility upon the addition of the metal chelator EDTA. The copper binding constant was found to be 4.72 ± 0.84 µM. In addition, Cu²⁺-bound iLOV showed high fluorescence quenching at near physiological pH. Further computational analysis yielded a better insight into understanding the possible amino acids responsible for Cu²⁺ binding with the iLOV protein.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1732-1736
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• 2014

Red fluorescent organic nanopaticles (FONs) based on a diarylacrylonitrile derivative conjugated molecule were facilely prepared by surfactant modification. Such red FONs showed excellent water solubility and biocompatibility, making them promising for cell imaging applications.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1221-1223
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• 2007

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.119-122
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• 2003

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.271-278
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• 1995

The relative distribution ratio of barbiturates between hyarocarbon interior and surface region of outer monolayer of synaptosomal plasma membrane vesicles (RSPMV) isolated from rat whole brain was determined by employing the fluorescent probe technique. The two fluorescent probes N- octadecylnaphthyl-2-amine-6-sulfonic acid (ONS) and 12-(9-anthroyloxy) stearic acid (AS) were utilized as probes for hydrocarbon interior and surface of outer monolayer of RSPMV. respectively. The Stern-Volmer equation for fluorescent quenching was modified to calculate the relative distribution ratio. The analysis of preferential quenching of these probes by barbiturates indicates that pentobarbital, hexobarbital, amobarbital and phenobarbital are predominantly distributed on the surface region. whereas thiopental sodium has an accessibility to the hydrocarbon interior of the outer monolayer of the RSPMV. From these results, it is strongly suggested that the more effective penetration into the hydrocarbon interior of the outer monolayer of the membrane lipid bilayer could result in higher general anesthetic activity.

• Current Applied Physics
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• v.18 no.11
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• pp.1255-1260
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• 2018

In this work, a green and simple one-pot route was developed for the synthesis of highly fluorescent aminofunctionalized graphene quantum dots (a-GQDs) via hydrothermal process without any further modification or surface passivation. We synthesized the a-GQDs using glucose as the carbon source and ammonium as a functionalizing agent without the use of a strong acid, oxidant, or other toxic chemical reagent. The as-obtained aGQDs have a uniform size of 3-4 nm, high contents of amino groups, and show a bright green emission with high quantum yield of 32.8%. Furthermore, the a-GQDs show effective fluorescence quenching for $Cu^{2+}$ ions which can serve as effective fluorescent probe for the detection of $Cu^{2+}$. The fluorescent probe using the obtained aGQDs exhibits high sensitivity and selectivity toward $Cu^{2+}$ with the limit of detection as low as 5.6 nM. The mechanism of the $Cu^{2+}$ induced fluorescence quenching of a-GQDs can be attributed to the electron transfer by the formation of metal complex between $Cu^{2+}$ and the amino groups on the surface of a-GQDs. These results suggest great potential for the simple and green synthesis of functionalized GQDs and a practical sensing platform for $Cu^{2+}$ detection in environmental and biological applications.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2195-2199
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• 2007

We demonstrate that high-resolution (~60 nm) near-field fluorescence images of fluorescent nanospheres can be obtained by utilizing the tip-induced fluorescence quenching process. A time-stamped photon counting (TSPC) technique employed enables us to efficiently measure the degree of fluorescence quenching caused by the dielectric or metallic atomic force microscopy tip. We find that the degree of quenching is not only determined by the tip-material but also by the local morphology of the tip. The fringe patterns around individual nanospheres observed are explained in terms of the interference between the excitation field that is directly induced by the laser source, and the scattered excitation field from the tip.

• KSBB Journal
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• v.22 no.1
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• pp.48-52
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• 2007

This study was carried out to establish the optimum disruption condition of a sonificator for the protein toxin for the purpose of developing automatic biological agent detector equipped a sonificator. One of the best-known collisional quenchers is molecular oxygen, which quenches almost all known fluorophores. The sonification does an excellent job of degassing, which decreased the quenching effect and increased the fluorescence quantity. The fluorescence measurement for the protein using 0.7 X fluorescent dye concentration and above must be done in 1 minute and the fluorescence measurement for the protein using 0.3 X fluorescent dye concentration and below has to be done between 2 and 3 minute. The fluorescence quantity of the sonificatied protein sample was much higher that of the non-sonificatied protein sample. Sonificating the sample turned out to be favorable for the fluorescence measurement when measuring at the low protein concentration.