Spectroscopic Studies upon Silver Nanoclusters Formed on Oligonucleotides Containing a Tricyclic Cytosine Analogue, tC

Silver nanoclusters (AgNCs) generated on DNA templates belong to a new class of fluorescent tags showing excellent brightness, photostability and biocompatibility. Thus, AgNCs-DNA has been applied in various applications, from the detection of DNA/RNA and environmental monitoring to bioimaging and cancer therapy. In this work, we report fluorescent AgNCs synthesized using two 1,3-diaza-2-oxophenothiazine (tC)-modified oligonucleotides that contain RET-related sequence CCCCGCCCCGCCCCGCCCCA. The communication compares the absorption and emission properties of the obtained systems with silver nanoclusters synthesized on the unmodified oligonucleotide. First, we showed the optimal conditions for AgNCs-DNA synthesis on three DNA templates: (1) RET20 with the sequence 5′-CCC CGC CCC GCC CCG CCC CA-3′; (2) RET19tC with the sequence 5′-CCC CGC CCC GCC CCG CCC tCA-3′; and (3) RET14tC with the sequence 5′-CCC CGC CCC GCC CtCG CCC CA-3′. Next, the silver nanoclusters were characterized by UV/Vis absorption, fluorescence and circular dichroism spectroscopy. Silver nanoclusters RET19tC-AgNCs and RET14tC-AgNCs indicated several times higher fluorescence intensities in the long-wave emission spectra as compared to RET20-AgNCs. Moreover, silver nanoclusters on tC-modified oligonucleotides showed higher stability over time. The possibility of using the silver nanoclusters RET19tC-AgNCs for monitoring pH changes will be also tested.

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The Problematic Charge-Transfer Triplet State of Electron-Donor-Acceptor-Complexes

Zeitschrift für Naturforschung A ◽

10.1515/zna-1970-1222 ◽

1970 ◽

Vol 25 (12) ◽

pp. 1925-1931

Author(s):

G. Briegleb ◽

D. Wolf

Keyword(s):

Charge Transfer ◽

Triplet State ◽

Spectral Range ◽

Emission Band ◽

Emission Spectra ◽

Electron Donors ◽

Excited Triplet ◽

Long Wave ◽

Donor Acceptor ◽

Wave Emission

Abstract Iwata, Tanaka and Nagakura, and Hayashi, Iwata and Nagakura have observed in ethylether-isopentane solutions (1 : 1) at 77 °K, in the case of the complexes of tetracyanobenzene (TCNB) as the electron acceptor with the electron donors mesitylene (Me), durene (Du) and hexamethyl-benzene (HMB), an unstructured long-lived, long-wave emission band by exciting the complexes in the charge transfer (CT) band. They interpreted the 11, lw band as a CT-phosphorescence of a t t charge transfer triplet excited state | D + A" | . This would be of considerable theoretical interest and significance also for an interpretation of photochemical processes. In the present communication, we report results which lead us to a different interpretation of the 11, lw emission band under discussion. The emission spectra of the complexes of tetracyanobenzene (TCNB) with the electron donors toluene (To), p-xylene (Xy), mesitylene (Me), durene (Du) and hexamethylbenzene (HMB) were studied in glassy solutions in propylether at 100 °K. In the case of TCNB-To, -Xy, -Me and -Du, when the complexes were irradiated in the CT-band so that the complex components were not excited, we observed either the structured phosporescence band of TCNB which originates from a locally excited triplet state of complexed TCNB or, at large donor concentrations, the unstructured long-lived, long-wave emission band within the green spectral range. In the case of TCNB-HMB, only the 11, lw emission may be observed. The 11, lw unstructured emission superimposed on the structured TCNB phosphorescence may also be observed when TCNB, singly soluted in glassy solvents or crystallized, is irradiated in the 31,600 cm -1 (St S0) peak. Obviously, the 11, lw emission band may not be characteristic of the complexes of TCNB. Simultaneously with the 11, lw emission, a new molecular species X can be identified by a new absorption spectrum after irradiating either TCNB itself within the S0 —St 31,600 cm -1 peak or the TCNB-complexes within the CT-absorption band. X is formed by a reaction of the triplet ex-cited TCNB. The excitation in the long-wave absorption peak of X at about 21,000 — 22,000 cm -1 gives rise to an emission with a maximum in the same spectral range as the 11, lw emission band. Accordingly, we interpret the 11, lw emission as a delayed emission of X due to an energy transfer from the triplet excited TCNB.

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Optical properties of hemicyanines with terminal amino groups and their applications in near-infrared fluorescent imaging of nucleoli

Journal of Materials Chemistry B ◽

10.1039/c4tb01218f ◽

2014 ◽

Vol 2 (40) ◽

pp. 7065-7072 ◽

Cited By ~ 18

Author(s):

Jia-Tao Miao ◽

Chen Fan ◽

Ru Sun ◽

Yu-Jie Xu ◽

Jian-Feng Ge

Keyword(s):

Optical Properties ◽

Near Infrared ◽

Water Solubility ◽

Stokes Shift ◽

Fluorescent Imaging ◽

Amino Groups ◽

Long Wave ◽

Terminal Amino ◽

Wave Emission ◽

Low Cytotoxicity

A cellular dye with properties of long-wave emission, large Stokes shift, water solubility, low cytotoxicity, and good photostability is reported.

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Spectroscopic studies on Tb3+ binding to S-100a protein

Biochemical Journal ◽

10.1042/bj2440559 ◽

1987 ◽

Vol 244 (3) ◽

pp. 559-563 ◽

Cited By ~ 2

Author(s):

R S Mani ◽

C M Kay

Keyword(s):

Conformational Changes ◽

Binding Assay ◽

Emission Spectra ◽

Spectroscopic Studies ◽

Spectral Studies ◽

Difference Spectroscopy ◽

Fluorescence Excitation ◽

Fluorescence Studies ◽

Helical Content ◽

Direct Binding

Direct binding assay and fluorescence studies revealed that S-100a protein binds 2 mol of Tb3+/mol of protein at pH 6.6. The protein binds Tb3+ much more tightly than Ca2+, and the upper limit of the observed Kd value for Tb3+ is 3.5 × 10(-6) M. The Tb3+-binding site on the protein must be close to a tyrosine residue, as indicated by fluorescence excitation and emission spectra, where energy transfer from tyrosine is noted. Addition of Tb3+ resulted in a conformational change in the protein, as revealed by u.v.-difference spectroscopy and c.d. studies. Far-u.v. c.d. studies indicated the helical content to decrease from approx. 39% to 35% in the presence of Tb3+. From u.v.-difference-spectroscopy results the single tryptophan and the tyrosine chromophores in S-100a protein are blue-shifted (i.e. exposed to the solvent) in the presence of Tb3+ and the observed conformational changes are similar to those induced by Ca2+, suggesting that Tb3+ can be employed as a Ca2+ analogue in spectral studies with S-100a protein.

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Vibrational spectroscopic studies of a new class of oligophosphate glasses of biological interest

Journal of Raman Spectroscopy ◽

10.1002/jrs.1250110105 ◽

1981 ◽

Vol 11 (1) ◽

pp. 10-13 ◽

Cited By ~ 14

Author(s):

A. Bertoluzza ◽

C. Fagnano ◽

V. Fawcett ◽

D. A. Long ◽

L. H. Taylor

Keyword(s):

Spectroscopic Studies ◽

New Class ◽

Biological Interest

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Spectroscopic Studies of Copper and Silver Binding to Metallothioneins

Metal-Based Drugs ◽

10.1155/mbd.1999.277 ◽

1999 ◽

Vol 6 (4-5) ◽

pp. 277-290 ◽

Cited By ~ 11

Author(s):

Martin J. Stillman

Keyword(s):

Spectral Data ◽

Metal Binding ◽

Emission Spectra ◽

Structural Data ◽

Spectroscopic Studies ◽

Yeast Cells ◽

Luminescence Spectra ◽

Ionization Mass ◽

Mass Spectral ◽

Metal Free

Mammalian metallothionein is remarkable in its metal binding properties: well-characterized species exist for metal to sulfur ratios of M7S20, M12S20, and M18S20, where M = Cd(ll), Zn(ll), Hg(ll), Ag(I), Au(I), and Cu(I). Circular dichroism and luminescence spectra provide rich details of a complicated metal binding chemistry when metals are added directly to the metal free- or zinc-containing protein. CD spectral data unambiguously identify key metal to protein stoichiometric ratios that result in well-defined structures. Emission spectra in the 450-750 nm region have been reported for metallothioneins containing Ag(I), Au(I), and Cu(I). The luminescence of Cu-MT can also be detected directly from mammalian and yeast cells. Qualitative and quantitative interpretations show that the final structure adopted by Ag-MT is not the same as that formed by Cu(I) ions in Cu-MT. XAFS structural data are reported for a number of metallothioneins, including Ag12-MT and Ag17-MT. Electrospray ionization mass spectrometry provides details on the species formed when Ag(I) binds to metallothionein. Mass spectral data are reported for metal-free MT 2A and Agn-MT (n = 14-18).

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Organic Syntheses and Characteristics of Novel Conjugated Polymers for AMOLEDs

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.75.91 ◽

2010 ◽

Vol 75 ◽

pp. 91-96

Author(s):

Su Hee Song ◽

Young Eup Jin ◽

Joo Young Shim ◽

Kwang Hee Lee ◽

Hong Suk Suh

Keyword(s):

Conjugated Polymers ◽

Blue Emission ◽

Wavelength Region ◽

Emission Spectra ◽

Polymer Backbone ◽

Light Emitting ◽

Long Wavelength ◽

New Class ◽

Solid Thin Films ◽

Pl Emission

Conjugated polymers with a stabilized blue emission are of importance for the realization of large flat panel AMOLED displays using polymer light-emitting diodes. Several novel conjugated polymers using newly developed templates for the stabilized EL emission are reported. Poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) is a new class of blue-emitting polymers utilizing a new back-bone. This material emits a efficient blue EL without exhibiting any unwanted peak in the long wavelength region (green region) even after prolonged annealing at an elevated temperature of 150oC in air, or operation of the device. New electroluminescent spiro-PCPPs, poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene))) (spiro-PCPP-alt-PCPP) and poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(1,4-phenylene)) (spiro-PCPPP), have been synthesized by the Suzuki polymerization. The PL emission spectra of polymers in THF solution show a same maximum peak at 397 nm. The maximum PL emission spectra of polymers appeared at around 463 and 456 nm in solid state, respectively. The PL spectra in solid thin films show more red-shifted over 60 nm than solution conditions. The blue emissions at 400-409 nm for the π–π* transitions of conjugated polymer backbone are almost completely quenched or decreased.

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The effect of local optically thick regions in the long-wave emission of young circumstellar disks

Astronomy and Astrophysics ◽

10.1051/0004-6361/201118296 ◽

2012 ◽

Vol 540 ◽

pp. A6 ◽

Cited By ~ 43

Author(s):

L. Ricci ◽

F. Trotta ◽

L. Testi ◽

A. Natta ◽

A. Isella ◽

...

Keyword(s):

Circumstellar Disks ◽

Long Wave ◽

Wave Emission

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A NEW CLASS OF IONIC SOLVENTS, ELECTROLYTES AND ENGINEERING FLUIDS BASED ON 1,3-ALKYLMETHYL-1,2,3-BENZOTRIAZOLIUM SALTS

Indonesian Journal of Chemistry ◽

10.22146/ijc.21744 ◽

2010 ◽

Vol 6 (2) ◽

pp. 111-116 ◽

Cited By ~ 1

Author(s):

Ahmad Mudzakir

Keyword(s):

Ionic Liquids ◽

Single Crystal ◽

Thermal Analyses ◽

Spectroscopic Studies ◽

Electrochemical Analysis ◽

Electrochemical Characteristics ◽

Melting Points ◽

X Ray ◽

Good Thermal Stability ◽

New Class

A new series of ionic liquids based on 1,3-alkylmethyl-1,2,3-benzotriazolium cation has been prepared. The spectroscopic, physical and electrochemical characteristics of this family of salts have been investigated with respect to potential usage as ionic solvents, electrolytes and engineering fluids. Incorporation of diverse anions including weak coordinating anion and pseudohalide with this benzotriazolium cation produces ionic liquids with advantageously low melting points and good thermal stability. Thermal analyses of these very stable salts included the determination of melting points (-65 to 164 oC) and decomposition temperatures (up to 291 oC). The electrochemical windows of representative benzotriazolium species has been investigated by cyclic voltammetry and determined to be ~ 3 V. The X-ray single crystal and spectroscopic studies revealed that weak hydrogen-bonding interactions between the benzotriazolium ring protons and the anions are present both in the solid state as well as in solution. Keywords: ionic liquids, X-ray single crystal, thermal analysis, electrochemical analysis, benzotriazolium salt

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Establishing empirical design rules of nucleic acid templates for the synthesis of silver nanoclusters with tunable photoluminescence and functionalities towards targeted bioimaging applications

Nanoscale Advances ◽

10.1039/d0na00381f ◽

2020 ◽

Vol 2 (9) ◽

pp. 3921-3932 ◽

Cited By ~ 1

Author(s):

Jason Y. C. Lim ◽

Yong Yu ◽

Guorui Jin ◽

Kai Li ◽

Yi Lu ◽

...

Keyword(s):

Nucleic Acid ◽

Silver Nanoclusters ◽

Cell Targeting ◽

Dna Templates ◽

Design Rules ◽

Empirical Design

Decoding empirical design rules of DNA templates for customizable synthesis of ultrasmall silver nanoclusters with predictable photoluminescence and cell-targeting properties.

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