Fluorescent AgNCs Formed on Bifunctional DNA Template for Potassium Ion Detection

In this study, we examined properties of silver nanoclusters, which are AgNCs stabilized by DNA oligonucleotide scaffold containing G-quadruplex-forming sequences: human telomeric (Tel22) or thrombin-binding aptamer (TBA). Thus, we obtained two fluorescent probes abbreviated as Tel22C12-AgNCs and TBAC12-AgNCs, which were characterized using absorption, circular dichroism and fluorescence spectroscopy. Both probes emit green and red fluorescence. The presence of silver nanoclusters did not destabilize the formed G-quadruplexes. The structural changes of probes upon binding K+ or Na+ ions cause quenching in their red emission. Green emission was slightly quenched only in the case of Tel22C12-AgNCs; on the contrary, for TBAC12-AgNC’s green emission, we observed an increasing fluorescence signal. Moreover, the Tel22C12-AgNCs system shows not only a higher binding preference for K+ over Na+, but it was able to monitor small changes in K+ concentrations in the buffer mimicking extracellular conditions (high content of Na+ ions). These results suggest that Tel22C12-AgNCs exhibit the potential to monitor transmembrane potassium transport.

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A label-free ultrasensitive and selective strategy for Pb(ii) assay by a multifunctional DNA probe-mediated rolling-circle amplified synthesis of the G-quadruplexes

Analytical Methods ◽

10.1039/c8ay00762d ◽

2018 ◽

Vol 10 (25) ◽

pp. 3081-3088 ◽

Cited By ~ 4

Author(s):

Xiao-Feng Wang ◽

Yong-Sheng Wang ◽

Xi-Lin Xiao ◽

Wen-Bo Lan ◽

Bin Zhou ◽

...

Keyword(s):

Dna Probe ◽

Fluorescence Signal ◽

Label Free ◽

Rolling Circle ◽

G Quadruplex ◽

Selective Strategy ◽

Dna Template

The cleavage of the S-DNA in a MDP by Pb(ii) can release an E-DNA, which initiates a RCA reaction with a padlock DNA template. The formed G-quadruplex could specifically bind to NMM to result in an amplified fluorescence signal.

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Efficient Editing of Silver Nanoclusters by Changing Simply One Cytosine in a DNA Template

ChemBioChem ◽

10.1002/cbic.202000640 ◽

2020 ◽

Author(s):

Jinliang Ma ◽

Kexin Li ◽

Shaobin Gu

Keyword(s):

Silver Nanoclusters ◽

Dna Template

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Chasing Particularities of Guanine- and Cytosine-Rich DNA Strands

Molecules ◽

10.3390/molecules25030434 ◽

2020 ◽

Vol 25 (3) ◽

pp. 434 ◽

Cited By ~ 4

Author(s):

Marko Trajkovski ◽

Janez Plavec

Keyword(s):

Structural Changes ◽

Polyacrylamide Gel Electrophoresis ◽

Dna Recombination ◽

Cd Spectroscopy ◽

G Quadruplex ◽

Recombination Processes ◽

Dna Strands ◽

Native Polyacrylamide Gel Electrophoresis ◽

Myc Gene

By substitution of natural nucleotides by their abasic analogs (i.e., 1′,2′-dideoxyribose phosphate residue) at critically chosen positions within 27-bp DNA constructs originating from the first intron of N-myc gene, we hindered hybridization within the guanine- and cytosine-rich central region and followed formation of non-canonical structures. The impeded hybridization between the complementary strands leads to time-dependent structural transformations of guanine-rich strand that are herein characterized with the use of solution-state NMR, CD spectroscopy, and native polyacrylamide gel electrophoresis. Moreover, the DNA structural changes involve transformation of intra- into inter-molecular G-quadruplex structures that are thermodynamically favored. Intriguingly, the transition occurs in the presence of complementary cytosine-rich strands highlighting the inability of Watson–Crick base-pairing to preclude the transformation between G-quadruplex structures that occurs via intertwining mechanism and corroborates a role of G-quadruplex structures in DNA recombination processes.

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Structure and Up-Conversion Luminescence Properties of Er3+-Yb3+Co-Doped TiO2 Nanocrystals Prepared by Sol-Gel Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.66.167 ◽

2009 ◽

Vol 66 ◽

pp. 167-170 ◽

Cited By ~ 8

Author(s):

Zhen Zhong Zhang ◽

Ji Hong Zhang ◽

Wei Zhou ◽

Ming Xia Song ◽

Wei Li ◽

...

Keyword(s):

Titanium Tetrachloride ◽

Upconversion Luminescence ◽

Sol Gel ◽

Green Emission ◽

X Ray Diffraction ◽

Red Emission ◽

Gel Method ◽

X Ray ◽

Sol Gel Method ◽

Co Doped

Er3+/Yb3+ co-doped TiO2 nanocrystals were prepared by Sol-gel method in which titanium tetrachloride was adopted as the precursor. The structure, particle size, and optical properties of samples were characterized by X-ray diffraction(XRD), Field emission-Scanning Electron Microscopy(FE-SEM) and photoluminescence(PL) spectra. Er3+ concentration was fixed at 1.0mol%, and Yb3+ concentration was changed from 3 to 10mol%. Intense upconversion luminescence was observed when the samples were excited by 980nm laser. The dependence of upconversion luminescence on Yb3+ concentration was presented. The results show that the upconversion luminescence increases with the Yb3+ concentration and gets its peak at 5%. The ratio of red emission to green emission(R/G) was strikingly enhanced with the increase of Yb3+ concentration. Under the excitation of 980nm, the green emission in the range of 520-570nm (2H11/2, 4S3/2→4I15/2) and the red emission in the range of 640~690nm (4F9/2 →4I15/2) are both due to two photons process. The possible upconversion mechanism was discussed.

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Novel Tunable Green-Red Luminescence in Mn2+ Doped Ca9Tb(PO4)7 Phosphors Based on the Mn2+ Regulation and Energy Transfer

Coatings ◽

10.3390/coatings10100952 ◽

2020 ◽

Vol 10 (10) ◽

pp. 952

Author(s):

Bingwen Yang ◽

Yefeng Feng ◽

Qinghu Zhao ◽

Miao He ◽

Yang Lv

Keyword(s):

Energy Transfer ◽

Green Emission ◽

Energy Transfer Mechanism ◽

Red Emission ◽

Broadband Emission ◽

Characteristic Emission ◽

Potential Applications ◽

Light Excitation ◽

Red Luminescence ◽

Thermal Stability Of

β-Ca3(PO4)2 type phosphors Ca9Tb(PO4)7:Mn2+ were fabricated by high temperature solid state reaction. Under 377 nm light excitation, the Ca9Tb(PO4)7 host displays the green emission attributable to the characteristic emission of Tb3+ ions peaking at 488, 542, 586, and 620 nm, respectively. The red broadband emission is observed when Ca9Tb(PO4)7 is doped with Mn2+ ions. The emission is attributed to the energy transfer from Tb3+ to Mn2+ ions; this facilitates the realization of the tunable green–red emission. The energy transfer mechanism from Tb3+ to Mn2+ is defined as quadrupole–quadrupole interaction. Furthermore, the thermal stability of Ca9Tb(PO4)7:Mn2+ samples has been studied, and it can maintain half the emission intensity exceeding 424 K. This demonstrates their potential applications in white light LEDs (w-LEDs).

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Nucleolin stabilizes G-quadruplex structures folded by the LTR promoter and silences HIV-1 viral transcription

Nucleic Acids Research ◽

10.1093/nar/gkv897 ◽

2015 ◽

Vol 43 (18) ◽

pp. 8884-8897 ◽

Cited By ~ 63

Author(s):

Elena Tosoni ◽

Ilaria Frasson ◽

Matteo Scalabrin ◽

Rosalba Perrone ◽

Elena Butovskaya ◽

...

Keyword(s):

Transcriptional Activity ◽

Cellular Protein ◽

Spectrometric Analysis ◽

Viral Transcription ◽

Mobility Shift ◽

Binding Preference ◽

G Quadruplex ◽

Mobility Shift Assay ◽

Ltr Promoter ◽

Hiv 1

Abstract Folding of the LTR promoter into dynamic G-quadruplex conformations has been shown to suppress its transcriptional activity in HIV-1. Here we sought to identify the proteins that control the folding of this region of proviral genome by inducing/stabilizing G-quadruplex structures. The implementation of electrophorethic mobility shift assay and pull-down experiments coupled with mass spectrometric analysis revealed that the cellular protein nucleolin is able to specifically recognize G-quadruplex structures present in the LTR promoter. Nucleolin recognized with high affinity and specificity the majority, but not all the possible G-quadruplexes folded by this sequence. In addition, it displayed greater binding preference towards DNA than RNA G-quadruplexes, thus indicating two levels of selectivity based on the sequence and nature of the target. The interaction translated into stabilization of the LTR G-quadruplexes and increased promoter silencing activity; in contrast, disruption of nucleolin binding in cells by both siRNAs and a nucleolin binding aptamer greatly increased LTR promoter activity. These data indicate that nucleolin possesses a specific and regulated activity toward the HIV-1 LTR promoter, which is mediated by G-quadruplexes. These observations provide new essential insights into viral transcription and a possible low mutagenic target for antiretroviral therapy.

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Composition-Dependent Ultraviolet up-Conversion Luminescence in Yb3+-Ho3+ Co-Doped Germanium- Phosphate Glasses

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.266.5 ◽

2011 ◽

Vol 266 ◽

pp. 5-8 ◽

Cited By ~ 1

Author(s):

Yan Min Yang ◽

Wei Zhang ◽

Shan Du ◽

Zhi Ping Yang

Keyword(s):

Emission Intensity ◽

Glass Sample ◽

Green Emission ◽

Phosphate Glasses ◽

Ultraviolet Emission ◽

Red Emission ◽

Excitation Mechanisms ◽

Uv Visible ◽

Holmium Ion ◽

Co Doped

Yb3+-Ho3+ co-doped germanium-phosphate glasses have been prepared and characterized for its optical properties through measuring photoluminescence and Raman spectra. UV-visible up-conversion emission of holmium ion in Yb3+-Ho3+ co-doped germanium-phosphate glasses has been observed on 980nm excitation. As phosphate was substituted for germanium the red emission Red I decreased at first and then increased later while the green emission Green I decreased and the ratio of Red I to Green I increased. Interestingly, the value of ultraviolet emission intensity was larger than that of the blue and green emission intensity in phosphate glass sample. We believe that Yb3+-Ho3+ co-doped germanium-phosphate glasses might be a potential host material for developing ultraviolet all–solid compact lasers. The possible excitation mechanisms involved in these emissions were discussed, too.

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Tuning Upconversion Emission of -NaGdF4:Yb3+/Ho3+ Nanorods Through Yb3+

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2016.11812 ◽

2016 ◽

Vol 16 (4) ◽

pp. 3754-3758 ◽

Cited By ~ 2

Author(s):

Fangqi Gao ◽

Wei Gao ◽

Ruibo Wang ◽

Longxiang Yan ◽

Jinping Li ◽

...

Keyword(s):

Sample Size ◽

Relaxation Process ◽

Solvothermal Method ◽

Fluorescence Emission ◽

Green Emission ◽

Upconversion Emission ◽

Cross Relaxation ◽

Red Emission ◽

Cross Relaxation Process ◽

Upconversion Mechanism

Yb3+/Ho3+ doped hexagonal NaGdF4 nanocrystals are synthesized through solvothermal method, for which pure hexagonal phased nanorods are presented. The concentration influence of Yb3+ ions on the sample morphology and fluorescence emission of Ho3+ is investigated. It is found that the sample size is changed from 25 nm to 125 nm and the upconversion emission is tuned from green to yellow when the concentration of Yb3+ ions is increased from 5.0 mol% to 50.0 mol%. The possible upconversion mechanism and the improvement of crystallinity are carefully investigated. It is suggested that the cross-relaxation process between Ho3+ ions promotes the red emission and quenches the green emission.

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