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RISS 인기검색어
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- 저자 : ( Rati Ranjan Nayak ) (검색결과 4 건)
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Rati Ranjan Nayak,Okhil Kumar Nag,Han Young Woo*,황승구,Doojin Vak,Dmitry Korystov,진영읍,서홍석 한국물리학회 2009 Current Applied Physics Vol.9 No.3
Two cationic conjugated polyelectrolytes (CPs, P1i and P2i) were ynthesized and examined as a fluorescence resonance energy transfer (FRET) donor to fluorescein (Fl)-labeled single-stranded DNA (ssDNA–Fl) using steady-state and time-resolved photoluminescence (PL) spectroscopy. The two polymers have the same p-conjugation with the main structural difference being the presence of the spiro-anthracenyl substituents orthogonal to the polymer backbone of P2i. These spiro-substituents can function as a molecular spacer that increases the intermolecular separation in the electrostatic complex with ssDNA–Fl. We measured almost complete PL quenching of the excited Fl* after electrostatic complexation with P1i (PL lifetime 4 ns→78 ps) and relatively moderate quenching with P2i (PL lifetime 4 ns→552 ps). A quenching efficiency (ΦeT) of 98% and 86% was obtained for P1i/ssDNA–Fl and for P2i/ssDNA–Fl, respectively. Both systems have same thermodynamic driving force for quenching as a result of them having the same electronic structures. This discrepancy can be explained in terms of the reduced quenching (via electron transfer, eT) by the increased D–A distance due to the existence of spiro-attached molecular spacers in P2i. It shows that thermodynamically favorable eT quenching can be controlled kinetically by modulating the D–A intermolecular distance using molecular spacers, which suggests an important molecular design guideline for efficient CPs-based DNA detection.
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A Micellar Complex of a Conjugated Polyelectrolyte for Efficient FRET to Dye-Labeled DNA
Nayak, Rati Ranjan,Nag, Okhil Kumar,Kang, Mijeong,Jin, Youngeup,Suh, Hongsuk,Lee, Kwanghee,Woo, Han Young WILEY-VCH Verlag 2009 Macromolecular Rapid Communications Vol.30 No.8
<P>A polymer–surfactant micellar complex has been studied as a fluorescence resonance energy transfer (FRET) donor to fluorescein-labeled DNA (ssDNA-Fl). In water, the molar absorptivity and fluorescence quantum efficiency of cationic poly(fluorene-co-phenylene) (c-PFP) are substantially increased in the presence of non-ionic surfactants. A TEM microscopic study shows the formation of a nanowire micellar complex of c-PFP and the surfactants. About a 400% enhancement of the FRET signal is measured in c-PFP/ssDNA-Fl with Brij 30, relative to that without surfactants. The signal amplification is successfully modulated using different types of non-ionic surfactants which perturb the complexation, fine-structure of the complex (i.e., donor-acceptor separation), and the resulting energy transfer process.</P><P> <img src='wiley_img/10221336-2009-30-8-MARC200800763-gra001.gif' alt='wiley_img/10221336-2009-30-8-MARC200800763-gra001'> </P>
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Water-Soluble Distyrylbenzene Fluorophore and Fluorescence Behavior in a Polymeric Vesicle
우한영,Nayak, Rati Ranjan,Woo, Han-Young 대한화학회 2007 대한화학회지 Vol.51 No.6
수용액에서 vesicle을 형성하는 고분자, poly(sodium acrylamidoundecanoate)(PSAU)와 수용성 형광다이, TPADSB-C를 합성하고 흡수 및 형광 분광기를 이용하여 광학적 특성을 연구하였다. N-phenyl naphthylamine을 형광 probe로 사용하여 PSAU의 농도가 0.01 g/L 이상에서 고분자들의 응집에 의해 vesicle을 형성함을 확인하였다. 수용성 형광다이의 형광 특성을 vesicle의 존재유무에 따라 조사함으로써 형광다이 주위의 미세환경의 변화에 따른 광학적 특성 의 변화를 측정하였다. 형광다이를 고분자 vesicle안에 침투시킬 경우 형광체 주변의 미세 환경(극성 등)의 변화에 따라 수용액 대비 발광 파장은 blue-shift하였고 형광 효율도 90%로 증가하였다. 본 연구는 형광다이를 함유하고 있는 고분 자 vesicle이 바이오이메징 응용에 있어 효과적이고 안정적이면서 biocompatible한 레이블용 테그로 사용될 수 있음을 보여준다. A vesicle forming polymer, poly(sodium acrylamidoundecanoate) (PSAU) and a water-soluble distyrylbenzene- based fluorophore, TPADSB-C were synthesized and characterized by using UV-vis and photoluminescence (PL) spectroscopy. An inter-chain vesicle formation of PSAU was observed at ~0.01 g/L from N-phenyl naphthylamine fluorescence measurement with changing PSAU concentration in water. Above critical aggregation concentration of PSAU, optical properties of TPADSB-C were investigated to study the microenvironment modulation through dye incorporation in the polymeric vesicle. The emission of TPADSB-C in the presence of PSAU vesicles was blue-shifted and the PL quantum efficiency was increased to 90% due to the microenvironment (e.g. polarity) change in aqueous solution. This study shows that the polymeric vesicle containing molecular fluorophores has a great potential as an efficient, stable and biocompatible labeling tag in biological cell imaging.
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( Jaya Shree Jena ),( Nilotpala Pradhan ),( Rati Ranjan Nayak ),( Bishnu P Dash ),( Lala Behari Sukla ),( Prasanna K Panda ),( Barada K Mishra ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.4
Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of Ag+ ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of Ag+ ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.
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