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DNA silver nanocluster

Hong-Ya Wang, Jin-Liang Ma, Bin-Cheng Yin, Bang-Ce Ye
We have developed a novel method for detecting nicotinamide adenine dinucleotide (NAD(+)) based on fluorescent silver nanoclusters (AgNCs) stabilized by a dumbbell-shaped DNA template containing two cytosine-loops joined in a dsDNA stem. The design involves two types of components: a dumbbell-shaped DNA template and three enzymes. In the presence of NAD(+) as a cofactor, Escherichia coli DNA ligase (E.coli DNA ligase) catalyzes template ligation to generate a sealed (no terminal nucleotides) dumbbell-shaped structure, preventing digestion by exonuclease III (Exo III) and exonuclease I (Exo I)...
April 20, 2017: Analyst
Morteza Hosseini, Shiva Mohammadi, Yasaman-Sadat Borghei, Mohammad Reza Ganjali
P53 mutation was detected through the application of a biosensing approach based on the decrease in the fluorescence of oligonucleotide-templated silver nanoclusters (DNA-AgNCs). To this end specific DNA scaffolds of two various nucleotide fragments were used. One of the scaffolds was enriched with two cytosine sequence fragment (C12). This led to DNA-AgNCs with a fluorescence intensity through chemical reduction, while the other scaffold acted as the probe fragment (5- GTAGATGGCCATGGCGCGGACGCGGGTG-3). This latter scaffold selectively bound to the specific p53 site...
April 13, 2017: Journal of Fluorescence
Lei Ge, Ximei Sun, Qing Hong, Feng Li
Although researches until now have emphasized the influence of an oligonucleotide sequence on the fluorescence of oligonucleotide-stabilized silver nanoclusters (AgNCs), this influence has been explored as a novel ratiometric fluorescent signal transduction in this work. This study builds on our original discovery of a template-transformation phenomenon, which demonstrated that the connection of a special DNA fragment (5'-CACCGCTTT-3') with a green-emitting AgNC nucleation sequence (GNuS, 5'-TGCCTTTTGGGGACGGATA-3') creates a red-emitting AgNC nucleation sequence (RNuS, 5'-CACCGCTTTTGCCTTTTGGGGACGGATA-3')...
April 10, 2017: ACS Applied Materials & Interfaces
Guifen Jie, Lu Tan, Yang Zhao, Xiaochun Wang
In this work, a novel silver nanoclusters (AgNCs) were in situ synthesized and used as versatile electrochemiluminescence (ECL) and electrochemical (EL) signal probes for thrombin detection by using DNAzyme-assisted target recycling and hybridization chain reaction (HCR) multiple amplification strategy. The presence of target thrombin firstly opened the hairpin DNA, followed by DNAzyme-catalytic recycling cleavage of excess substrates, which could generate large number of substrate fragments (s1). Then these s1 fragments were captured by SH-DNA on the Au nanoparticle-modified electrode, which further triggered the subsequent HCR of the hairpin DNA probes (H1 and H2) to form the long dsDNA...
March 7, 2017: Biosensors & Bioelectronics
Rui Cheng, Jing Xu, Xiafei Zhang, Zhilu Shi, Qi Zhang, Yan Jin
Herein, the conformational switch of G-rich oligonucleotide (GDNA) demonstrated the obvious functional switch of GDNA which was found to significantly affect the fluorescence of the in-situ synthesized DNA/silver nanocluster (DNA-AgNC) in homogeneous solution. We envisioned that the allosteric interaction between GDNA and DNA-AgNC would be possible to be used for screening telomere-binding ligands. A unimolecular probe (12C5TG) is ingeniously designed consisting of three contiguous DNA elements: G-rich telomeric DNA (GDNA) as molecular recognition sequence, T-rich DNA as linker and C-rich DNA as template of DNA-AgNC...
March 6, 2017: Scientific Reports
Jie Liu, Yuexiang Lu, Lu Feng, Song Wang, Shixi Zhang, Xuewei Zhu, Linfeng Sheng, Sichun Zhang, Xinrong Zhang
Single nucleotide polymorphisms (SNPs) are the most fundamental internal causes for many genetic diseases. However, the location information on SNPs in a specific DNA sequence is not well acquired through current SNPs detection methods, except for accurate DNA sequencing. Here we report a fluorescence enhancement phenomenon in the process of two silver nanoclusters (AgNCs) approaching closely to form a nanocluster dimer (NCD). The fluorescence intensity is sensitive to the distance between two AgNCs; therefore, the NCD lights into different fluorescence intensities upon binding SNPs targets with mismatched bases at different positions...
February 9, 2017: Analytical Chemistry
Emma N Hooley, Miguel R Carro-Temboury, Tom Vosch
Using single molecule polarization measurements, we investigate the excitation and emission polarization characteristics of DNA stabilized silver nanoclusters (C24-AgNCs). Although small changes in the polarization generally accompany changes to the emission spectrum, the emission and excitation transition dipoles tend to be steady over time and aligned in a similar direction, when immobilized in PVA. The emission transition dipole patterns, observed for C24-AgNCs in defocused wide field imaging, match that of a single emitter...
February 9, 2017: Journal of Physical Chemistry. A
Wei-Xian Wang, Yee-Wai Cheung, Roderick M Dirkzwager, Wai-Chung Wong, Julian A Tanner, Hong-Wei Li, Yuqing Wu
Innovative nanomaterials offer significant potential for diagnosis of severe diseases of the developing world such as malaria. Small sized silver nanoclusters have shown promise for diagnostics due to their intense fluorescence emission and photo-stabilities. Here, double-stranded DNA-scaffolded silver nanoclusters (AgNCs-dsDNA) were prepared to detect the established malaria biomarker, Plasmodium falciparum lactate dehydrogenase (PfLDH). Significant luminescence enhancement over a wide concentration range of PfLDH was demonstrated...
January 31, 2017: Analyst
Pratik Shah, Seok Keun Cho, Peter Waaben Thulstrup, Morten Jannik Bjerrum, Phil Hyu Lee, Ju-Hee Kang, Yong-Joo Bhang, Seong Wook Yang
MicroRNAs (miRNAs) are essential small RNA molecules (20-24 nt) that negatively regulate the expression of target genes at the post-transcriptional level. Due to their roles in a variety of biological processes, the aberrant expression profiles of miRNAs have been identified as biomarkers for many diseases, such as cancer, diabetes, cardiovascular disease and neurodegenerative diseases. In order to precisely, rapidly and economically monitor the expression of miRNAs, many cutting-edge nanotechnologies have been developed...
January 2017: Journal of Movement Disorders
Guoliang Liu, Jingjing Li, Da-Qian Feng, Jun-Jie Zhu, Wei Wang
An activatable silver nanoclusters beacon (ASNCB) was synthesized through a facile one-pot approach and applied for multiplex DNAs, small molecule, and protein sensing. Multifunctional single-stranded DNA sequences are rationally designed and used for ASNCB in situ synthesis. Via target-responsive structure transformation of ASNCB, target recognition induced ASNCB conformational transition and lit up the fluorescent signal of silver nanoclusters. By further implementing two different color ASNCBs (520 and 600 nm), the parallel multiplexed analysis of two target genes (Influenza A virus genes H1N1 and H5N1) is achieved...
January 3, 2017: Analytical Chemistry
Priyamvada Jain, Babina Chakma, Sanjukta Patra, Pranab Goswami
A set of 90 mer long ssDNA candidates, with different degrees of cytosine (C-levels) (% and clusters) was analyzed for their function as suitable Ag-nanocluster (AgNC) nucleation scaffolds. The sequence (P4) with highest C-level (42.2%) emerged as the only candidate supporting the nucleation process as evident from its intense fluorescence peak at λ660 nm. Shorter DNA subsets derived from P4 with only stable hairpin structures could support the AgNC formation. The secondary hairpin structures were confirmed by PAGE, and CD studies...
March 1, 2017: Analytica Chimica Acta
Siqi Zhang, Kun Wang, Kai-Bin Li, Wei Shi, Wen-Ping Jia, Xiaoying Chen, Ting Sun, De-Man Han
A silver nanoclusters (AgNCs)/graphene oxide (GO)-based fluorescence sensor was developed for label-free DNA detection through hybridization chain reaction (HCR). A DNA sequence associated with the human immunodeficiency virus (HIV) was selected as a model target. Two DNA probes, hairpin probe 1 (H1) and hairpin probe 2 (H2), were partially complementary. GO was used as an adsorption material to capture the hairpin probes and a selective fluorescence quencher was used to reduce the background signal. Upon addition of AgNO3 and NaBH4, the AgNCs were synthesized at the terminals of the H1 and H2 probes...
May 15, 2017: Biosensors & Bioelectronics
Wei Wang, Ting Bao, Xi Zeng, Huayu Xiong, Wei Wen, Xiuhua Zhang, Shengfu Wang
In this work, a novel and ultrasensitive electrochemical biosensor was constructed for DNA detection based on functionalized gold clusters/graphene nanohybrids (AuNCs/GR nanobybrids) and exonuclease III (Exo III)-aided cascade target recycling. By utilizing the capacity of GR as universal template, different metal nanoclusters including AuNCs/GR nanobybrids and PtNCs/GR nanohybrids were synthesized through convenient ultrasonic method. Exo III-aided cascade recycling was initiated by target DNA, generating the final cleavage product (S2), which acted as a linkage between capture probe and the functionalized metal nanoclusters/GR conjugates in the construction of the biosensor...
May 15, 2017: Biosensors & Bioelectronics
Mojtaba Shamsipur, Afshin Pashabadi, Fatemeh Molaabasi, Saman Hosseinkhani
It is well known that cytochrome c (Cyt c) is a crucial death regulator that triggers programmed cell death, apoptosis. Here, we report on the successful application of an aptamer bioconjugated nanoclusters for the detection of apoptosis based on release of cytochrome c from mitochondria in lysates human embryonic kidney cells HEK293T. The aptamer-conjugated silver nanoclusters (Apt@AgNCs) were synthesized and immobilized on gold electrode for impedimetric detection of Cyt c over the range of 0.15-375nM. It was found that the presence of Ag(I) ions shell at the surface of prepared NCs could increase their affinity to the donor groups (COO(-) and some amine groups in its deprotonated form, NH2) of cysteine attached on the gold electrode surface...
April 15, 2017: Biosensors & Bioelectronics
Yangfang Kuang, Sheng Liang, Fangfang Ma, Shu Chen, Yunfei Long, Rongjin Zeng
In this study, fluorescent silver nanoclusters (Ag NCs) were synthesized using denatured fish sperm DNA as the template. In contrast to other methods, this method did not use artificial DNA as the template. After their reaction with denatured fish sperm DNA, Ag(+) ions were reduced by NaBH4 to form Ag NCs. The Ag NCs showed a strong fluorescence emission at 650 nm when excited at 585 nm. The fluorescence intensity increased fourfold at pH 3.78, controlled with Britton-Robinson buffer solution. The fluorescence of the Ag NCs was quenched in the presence of trace mercury ions (Hg(2)(+) ) in a weakly acidic medium and nitrogen atmosphere...
November 27, 2016: Luminescence: the Journal of Biological and Chemical Luminescence
Cai-Xia Zhuo, Li-Hui Wang, Jing-Jing Feng, Yao-Dong Zhang
Trypsin is important during the regulation of pancreatic exocrine function. The detection of trypsin activity is currently limited because of the need for the substrate to be labeled with a fluorescent tag. A label-free fluorescent method has been developed to monitor trypsin activity. The designed peptide probe consists of six arginine molecules and a cysteine terminus and can be conjugated to DNA-stabilized silver nanoclusters (DNA-AgNCs) by Ag-S bonding to enhance fluorescence. The peptide probe can also be adsorbed to the surface of graphene oxide (GO), thus resulting in the fluorescence quenching of DNA-AgNCs-peptide conjugate because of Förster resonance energy transfer...
November 9, 2016: Sensors
Simon Gregersen, Tom Vosch, Knud J Jensen
Few-atom silver nanoclusters (AgNCs) can exhibit strong fluorescence; however, they require ligands to prevent aggregation into larger nanoparticles. Fluorescent AgNCs in biopolymer scaffolds have so far mainly been synthesized in solution, and peptides have only found limited use compared to DNA. Herein, we demonstrate how solid-phase methods can increase throughput dramatically in peptide ligand screening and in initial evaluation of fluorescence intensity and chemical stability of peptide-stabilized AgNCs (P-AgNCs)...
December 19, 2016: Chemistry: a European Journal
Gui-Mei Han, Zhen-Zhen Jia, Yan-Jun Zhu, Jia-Jia Jiao, De-Ming Kong, Xi-Zeng Feng
The high susceptibility of the natural D-conformation of DNA (D-DNA) to nucleases greatly limits the application of DNA-templated silver nanoclusters (Ag NCs) in biological matrixes. Here we demonstrate that the L-conformation of DNA (L-DNA), the enantiomer of D-DNA, can also be used for the preparation of aptamer-Ag NCs. The extraordinary resistance of L-DNA to nuclease digestion confers much higher biostability to these NCs than those templated by D-DNA, thus making cell-type-specific imaging possible at physiological temperatures, using at least 100-times lower Ag NC concentration than reported D-DNA-templated ones...
November 15, 2016: Analytical Chemistry
S Y New, S T Lee, X D Su
12 years after the introduction of DNA-templated silver nanoclusters (DNA-AgNCs), exciting progress has been made and yet we are still in the midst of trying to fully understand this nanomaterial. The prominent excellence of DNA-AgNCs is undoubtedly its modulatable emission property, of which how variation in DNA templates causes emission tuning remains elusive. Based on the up-to-date DNA-AgNCs, we aim to establish the correlation between the structure/sequence of DNA templates and emission behaviour of AgNCs...
October 7, 2016: Nanoscale
Peng Zhang, Hui Liu, Xiaocheng Li, Suzhen Ma, Shuai Men, Heng Wei, Jingjing Cui, Hongning Wang
The harm of Salmonella typhimurium (S. typhimurium) to public health mainly by the consumption of contaminated agricultural products or water stresses an urgent need for rapid detection methods to help control the spread of S. typhimurium. In this work, an intelligently designed sensor system took creative advantage of triple trigger sequences-regenerated strand displacement amplification and self-protective hairpin template-generated-scaffolded silver nanoclusters (AgNCs) for the first time. In the presence of live S...
January 15, 2017: Biosensors & Bioelectronics
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