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

2018 ◽  
Vol 10 (25) ◽  
pp. 3081-3088 ◽  
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.

scholarly journals A Label-Free Fluorescent Assay for the Rapid and Sensitive Detection of Adenosine Deaminase Activity and Inhibition

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2441 ◽  
Author(s):  
Xinxing Tang ◽  
Kefeng Wu ◽  
Han Zhao ◽  
Mingjian Chen ◽  
Changbei Ma
Keyword(s):  
Adenosine Deaminase ◽  
High Selectivity ◽  
High Sensitivity ◽  
Rnase H ◽  
Fluorescence Signal ◽  
Label Free ◽  
Fluorescent Assay ◽  
Adenosine Deaminase Activity ◽  
G Quadruplex ◽  
Almost All

Adenosine deaminase (ADA), able to catalyze the irreversible deamination of adenosine into inosine, can be found in almost all tissues and plays an important role in several diseases. In this work, we developed a label-free fluorescence method for the detection of adenosine deaminase activity and inhibition. In the presence of ADA, ATP has been shown to be hydrolyzed. The ATP aptamer was shown to form a G-quadruplex/thioflavin T (ThT) complex with ThT and exhibited an obvious fluorescence signal. However, the ATP aptamer could bind with ATP and exhibited a low fluorescence signal because of the absence of ADA. This assay showed high sensitivity to ADA with a detection limit of 1 U/L based on an SNR of 3 and got a good linear relationship within the range of 1–100 U/L with R2 = 0.9909. The LOD is lower than ADA cutoff value (4 U/L) in the clinical requirement and more sensitive than most of the reported methods. This technique exhibited high selectivity for ADA against hoGG I, UDG, RNase H and λexo. Moreover, this strategy was successfully applied for assaying the inhibition of ADA using erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) and, as such, demonstrated great potential for the future use in the diagnosis of ADA-relevant diseases, particularly in advanced drug development.

Label-free fluorometric detection of microRNA using isothermal rolling circle amplification generating tandem G-quadruplex

The Analyst ◽  
2020 ◽  
Vol 145 (18) ◽  
pp. 6130-6137
Author(s):  
Minhee Kim ◽  
Dong-Min Kim ◽  
Dong-Eun Kim
Keyword(s):  
Tandem Repeats ◽  
Rolling Circle Amplification ◽  
Thioflavin T ◽  
Fluorometric Detection ◽  
Label Free ◽  
Rolling Circle ◽  
G Quadruplex

Fluorometric detection of microRNA using Rolling Circle Amplification generating tandem G-quadruplex (GQ-RCA). Target miRNA triggers the GQ-RCA reaction generating tandem repeats of the G-quadruplex, resulting in enhanced Thioflavin T fluorescence.

scholarly journals Fluorescent AgNCs Formed on Bifunctional DNA Template for Potassium Ion Detection

Chemosensors ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 349
Author(s):  
Patrycja Filipczuk ◽  
Angelika Świtalska ◽  
Joanna Kosman ◽  
Grzegorz Nowaczyk ◽  
Anna Dembska
Keyword(s):  
Structural Changes ◽  
Green Emission ◽  
Potassium Transport ◽  
Silver Nanoclusters ◽  
Fluorescence Signal ◽  
Red Emission ◽  
Binding Preference ◽  
G Quadruplex ◽  
Na Ions ◽  
Dna Template

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.

scholarly journals Label-Free Fluorescence Molecular Beacon Probes Based on G-Triplex DNA and Thioflavin T for Protein Detection

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2962
Author(s):  
Jun Xue ◽  
Jintao Yi ◽  
Hui Zhou
Keyword(s):  
Molecular Beacon ◽  
Protein Detection ◽  
Thioflavin T ◽  
Fluorescence Labeling ◽  
Fluorescence Signal ◽  
Label Free ◽  
Biomedical Sciences ◽  
Exonuclease Iii ◽  
G Quadruplex ◽  
Exo Iii

Protein detection plays an important role in biological and biomedical sciences. The immunoassay based on fluorescence labeling has good specificity but a high labeling cost. Herein, on the basis of G-triplex molecular beacon (G3MB) and thioflavin T (ThT), we developed a simple and label-free biosensor for protein detection. The biotin and streptavidin were used as model enzymes. In the presence of target streptavidin (SA), the streptavidin hybridized with G3MB-b (biotin-linked-G-triplex molecular beacon) perfectly and formed larger steric hindrance, which hindered the hydrolysis of probes by exonuclease III (Exo III). In the absence of target streptavidin, the exonuclease III successively cleaved the stem of G3MB-b and released the G-rich sequences which self-assembled into a G-triplex and subsequently activated the fluorescence signal of thioflavin T. Compared with the traditional G-quadruplex molecular beacon (G4MB), the G3MB only needed a lower dosage of exonuclease III and a shorter reaction time to reach the optimal detection performance, because the concise sequence of G-triplex was good for the molecular beacon design. Moreover, fluorescence experiment results exhibited that the G3MB-b had good sensitivity and specificity for streptavidin detection. The developed label-free biosensor provides a valuable and general platform for protein detection.

A label-free fluorescent aptasensor based on HCR and G-quadruplex DNAzymes for the detection of prostate-specific antigen

The Analyst ◽  
2021 ◽  
Author(s):  
Ruirui Zhao ◽  
Lu Zhao ◽  
Haidi Feng ◽  
Xiaoliang Chen ◽  
Huilin Zhang ◽  
...  
Keyword(s):  
Prostate Specific Antigen ◽  
Specific Antigen ◽  
Label Free ◽  
Fluorescence Sensing ◽  
Sensing Platforms ◽  
G Quadruplex ◽  
Fluorescent Aptasensor

Fluorescence sensing platforms based on HCR and G-quadruplex DNAzyme amplification strategies for the detection of prostate-specific antigen.

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