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991.
The free solution mobilities of 26-base pair (bp) DNA oligomers containing A-tracts with and without internal ApT steps have been measured by capillary electrophoresis, using the mobility of a 26-bp random-sequence oligomer as a reference. The background electrolytes (BGEs) contained mixtures of Li+ and tetrapropylammonium (TPA+) ions, keeping the total cation concentration constant at 0.3 M. The mobility ratios equaled 1.00 in 0.3 M TPA+, indicating that the A-tract and reference oligomers had the same B-form conformation in this BGE. With increasing [Li+], the mobility ratio decreased as Li+ ions became localized in the A-tract minor groove, suggesting that the A-tract was now in the B* conformation. If the A-tract contained an internal ApT step and the oligomer contained less than ∼50% A + T, the mobility ratio reached a reduced plateau value that remained constant as the [Li+] increased to 0.3 M. However, for A-tracts without an internal ApT step and for A-tracts embedded in oligomers containing more than 50% A + T, the mobility ratios increased again at high [Li+], eventually reaching a plateau value of 1.00. Hence, DNA A-tracts in solution appear to exist as mixtures of the B and B* conformations, with the fractional concentration of each conformer depending on the [Li+], the A-tract sequence, and the total A + T content of the oligomer. 相似文献
992.
Ruyi Xu Zhaorui Chang Dan Wen Yi Liu Chudong Wang Weifeng Qu Xuan Tang Hongtao Jia Jienan Li Jifeng Cai Guanlin Li Bowei Jiang Lagabaiyila Zha 《Electrophoresis》2023,44(19-20):1579-1587
993.
Hamdi Ben Halima Abdelhamid Errachid Nicole Jaffrezic-Renault 《Electroanalysis》2023,35(1):e202100451
The review presents advances and main challenges of the affinity sensors based on field- effect transistors published during the last five years. The different nanomaterial-based field-effect transistors are classified according to the nature of the nanomaterials, beginning by silicon, the “gold-standard” semiconductor, the gallium nitride semiconductor, the organic semiconductors, the silicon nanowires, the inorganic nanomaterials, the carbon nanotubes and the graphene. Due to its exceptional electrical properties, the main works are devoted to graphene. The obtained analytical performances for the detection of biomarkers, of DNA sequences and of miRNA are listed. The relation between the operational conditions - nature of the nanomaterials, procedure of preparation, choice of the receptor molecule, method of immobilization – and the analytical performance are discussed. The perspective of industrialization of these affinity sensors based on field-effect transistors is discussed. 相似文献
994.
995.
Shuai Zhao Prof. Shaohua Zhang Huijun Hu Yangchang Cheng Kexuan Zou Prof. Jie Song Dr. Jinqi Deng Prof. Lele Li Prof. Xiao-Bing Zhang Prof. Guoliang Ke Prof. Jiashu Sun 《Angewandte Chemie (International ed. in English)》2023,62(24):e202303121
Mature microRNAs (miRNAs) in extracellular vesicles (EVs) are involved in different stages of cancer progression, yet it remains challenging to precisely detect mature miRNAs in EVs due to the presence of interfering RNAs (such as longer precursor miRNAs, pre-miRNAs) and the low abundance of tumor-associated miRNAs. By leveraging the size-selective ability of DNA cages and polyethylene glycol (PEG)-enhanced thermophoretic accumulation of EVs, we devised a DNA cage-based thermophoretic assay for highly sensitive, selective, and in situ detection of mature miRNAs in EVs with a low limit of detection (LoD) of 2.05 fM. Our assay can profile EV mature miRNAs directly in serum samples without the interference of pre-miRNAs and the need for ultracentrifugation. A clinical study showed that EV miR-21 or miR-155 had an overall accuracy of 90 % for discrimination between breast cancer patients and healthy donors, which outperformed conventional molecular probes detecting both mature miRNAs and pre-miRNAs. We envision that our assay can advance EV miRNA-based diagnosis of cancer. 相似文献
996.
A novel ion implantation sensor (DNA/COOH/ITO) based on DNA immobilization in COOH/ITO probe was manufactured for the first time. The surface morphologies of the electrodes were characterized by X‐ray photoelectron spectroscopy (XPS), field‐emission‐scanning electron microscopy (FSEM) and electrochemical methods. In a 0.5 mol/L PBS solution, a sensitive oxidation peak of DNA on the COOH/ITO electrode was obtained by voltammetry. The electrochemical behavior of DNA was studied. And the oxidative peak potential of DNA was +0.400 V (vs. Ag/AgCl). Its peak current was proportional to the concentration of DNA over the range of 1.0×10?8?1.0×10?6 mol/L with a detection limit of 5.0×10?9 mol/L (about 0.5 ng/mL). This sensor was applied to the direct detection of DNA samples. 相似文献
997.
998.
《中国科学B辑(英文版)》2008,(4)
The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied. The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanoparticles in different sizes and at various concentrations into the polymerase chain reaction (PCR) system. TiO2 nanoparticles were premixed with the DNA polymerase, the primer or the template, respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis. Sequentially the interaction be- tween TiO2 nanoparticles and the DNA polymerase, the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis (PAGE). The results suggest that TiO2 nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than mi- croscale TiO2 particles at the equivalent concentration and the inhibition effect of TiO2 nanoparticles is concentration dependent. The molecular mechanism of such inhibition is that in the dark, TiO2 nanoparticles interact with the DNA polymerase through physical adsorption while TiO2 nanoparticles do with the primer or the template in a chemical adsorption manner. The disfunction levels of the bio-molecules under the impact of TiO2 nanoparticles are in the following order: the primer > the tem- plate > the DNA polymerase. 相似文献
999.
Gold nanoparticles (nano Au)/titanium dioxide (TiO2) hollow microsphere membranes were prepared on the carbon paste electrode (CPE) for enhancing the sensitivity of DNA hybridization
detection. The immobilization of nano Au and TiO2 microsphere was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization
events were monitored with EIS using [Fe(CN)6]3−/4− as indicator. The sequence-specific DNA of the 35S promoter from cauliflower mosaic virus (CaMV35S) gene was detected with
this DNA electrochemical sensor. The dynamic detection range was from 1.0×10−12 to 1.0×10−8 mol/L DNA and a detection limit of 2.3×10−13 mol/L could be obtained. The polymerase chain reaction (PCR) amplification of the terminator of nopaline synthase (NOS) gene
from the real sample of a kind of transgenic soybean was also satisfactorily detected.
Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 and 20375020), Doctoral Foundation of the
Ministry of Education of China (Grant No. 20060426001) and Natural Science Foundation of Qingdao City (Grant No. 04-2-JZP-8) 相似文献
1000.
In this article, we report on efforts to construct a high sensitive electrochemical sensor with immobilized sandwich‐type DNA borne ferrocene (Fc) head for sequence‐specific DNA detection using ultramicroelectrode and low current voltammetry. Based on the difference in deformability between the bending rigid complementary DNA double helix and its anomalous flexile mismatches, the fully complementary target can be distinguished from mismatched targets including the single‐base mismatched target. Detection limit estimated as the amount of DNA is observed to be 100 fM via low current voltammetry. The method offers great promise of high sensitivity and selectivity simultaneously for effective gene identification. 相似文献