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21.
Fei Jia Nuo Duan Shijia Wu Xiaoyuan Ma Yu Xia Zhouping Wang Xinlin Wei 《Mikrochimica acta》2014,181(9-10):967-974
We describe here an aptasensor for the ultrasensitive detection of Staphylococcus aureus by electrochemical impedance spectroscopy (EIS). Single-stranded DNA was linked to a nanocomposite prepared from reduced graphene oxide (rGO) and gold nanoparticles (AuNP). Thiolated ssDNA was covalently linked to the AuNPs linked to rGO, and probe DNA was immobilized on the surface of an AuNP-modified glassy carbon electrode to capture and concentrate Staph. aureus. The probe DNA of the aptasensor selectively captures the target bacteria in its three-dimensional space, and these results in a dramatic increase in impedance. Scanning electron microscopy, cyclic voltammetry and EIS were used to monitor the single steps of the electrode assembly process. The effect was utilized to quantify the bacteria in the concentration range from 10 to 106 cfu mL?1 and with a detection limit of 10 cfu mL?1 (S/N?=?3). The relative standard deviation of Staphylococcus aureus detection was equal to 4.3 % (105 cfu mL?1, n?=?7). In addition to its sensitivity, the biosensor exhibits high selectivity over other pathogens. Figure
Schematic representation of the GCE surface modification and the detection of S. aureus. Reduced graphene oxide and gold nanoparticle (AuNP) nanocomposite linked by single-stranded DNA was prepared and then used in an aptasensor for the ultrasensitive detection of Staphylococcus aureus through electrochemical impedance spectroscopy. The probe DNA of the aptasensor selectively captures the target bacteria in its three-dimensional space, and these results in a dramatic increase in impedance. 相似文献
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Nuo Duan Shijia Wu Ye Yu Xiaoyuan Ma Yu Xia Xiujuan Chen Yukun Huang Zhouping Wang 《Analytica chimica acta》2013
A sensitive, specific method for the collection and detection of pathogenic bacteria was demonstrated using quantum dots (QDs) as a fluorescence marker coupled with aptamers as the molecular recognition element by flow cytometry. The aptamer sequences were selected using a bacterium-based SELEX strategy in our laboratory for Vibrio parahaemolyticus and Salmonella typhimurium that, when applied in this method, allows for the specific recognition of the bacteria from complex mixtures including shrimp samples. Aptamer-modified QDs (QD-apt) were employed to selectively capture and simultaneously detect the target bacteria with high sensitivity using the fluorescence of the labeled QDs. The signal intensity is amplified due to the high photostability of QDs nanoparticles, resulting in improved sensitivity over methods using individual dye-labeled probes. This proposed method is promising for the sensitive detection of other pathogenic bacteria in food stuff if suitable aptamers are chosen. The method may also provide another potential platform for the application of aptamer-conjugated QDs in flow cytometry. 相似文献
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Dr. Jenifer Pendiuk Gonçalves Duangkamol Promlok Tsvetomir Ivanov Shijia Tao Timo Rheinberger Seong-Min Jo Yingjie Yu Robert Graf Manfred Wagner Assoc. Prof. Daniel Crespy Frederik R. Wurm Dr. Lucas Caire da Silva Prof. Shuai Jiang Prof. Katharina Landfester 《Angewandte Chemie (International ed. in English)》2023,62(11):e202216966
Living organisms compartmentalize their catalytic reactions in membranes for increased efficiency and selectivity. To mimic the organelles of eukaryotic cells, we develop a mild approach for in situ encapsulating enzymes in aqueous-core silica nanocapsules. In order to confine the sol-gel reaction at the water/oil interface of miniemulsion, we introduce an aminosilane to the silica precursors, which serves as both catalyst and an amphiphilic anchor that electrostatically assembles with negatively charged hydrolyzed alkoxysilanes at the interface. The semi-permeable shell protects enzymes from proteolytic attack, and allows the transport of reactants and products. The enzyme-carrying nanocapsules, as synthetic nano-organelles, are able to perform cascade reactions when enveloped in a polymer vesicle, mimicking the hierarchically compartmentalized reactions in eukaryotic cells. This in situ encapsulation approach provides a versatile platform for the delivery of biomacromolecules. 相似文献
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Hua?Ye Nuo?Duan Shijia?Wu Guiliang?Tan Huajie?Gu Jinghong?Li Haitao?Wang Zhouping?WangEmail author 《Mikrochimica acta》2017,184(11):4235-4242
The authors describe a new kind of selection method (referred to as orientation selection) for improved screening for broad-spectrum lipopolysaccharides (LPSs) using unlabeled ssDNA aptamers. The method is based on the capture-SELEX technique using magnetic nanoparticles. LPS from Salmonella enterica serotype typhimurium was chosen as an exemplary target. Once the ssDNA library is preconcentrated to a certain degree, two Gram-negative bacteria were used as orientation molecules in the subsequent selection process. Using this strategy, one optimal aptamer ('EA7') was captured that has a high affinity (Kd = 102 ± 17 nM) for LPS and it was also confirmed that it can recognize three other bacterial LPSs. It is presumed that EA7 binds to the lipid A region of LPS. When using carboxyfluorescein labeled EA7, the observed fluorescence intensity and concentrations of four types of LPSs in drinking water are linearly correlated. The lower detection limit of the LPS is 3 ng·mL?1. Compared to multi-target mixed selection and conventional SELEX methods, the new orientation selection strategy produces results that are less uncertain. 相似文献
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Xiaojuan Ding Yurong Yan Shengqiang Li Ye Zhang Wei Cheng Quan Cheng Shijia Ding 《Analytica chimica acta》2015
MicroRNAs (miRNAs) play an important regulatory role in cells and dysregulation of miRNA has been associated with a variety of diseases, making them a promising biomarker. In this work, a novel biosensing strategy has been developed for label-free detection of miRNA using surface plasmon resonance (SPR) coupled with DNA super-sandwich assemblies and biotin–strepavidin based amplification. The target miRNA is selectively captured by surface-bound DNA probes. After hybridization, streptavidin is employed for signal amplification via binding with biotin on the long DNA super-sandwich assemblies, resulting in a large increase of the SPR signal. The method shows very high sensitivity, capable of detecting miRNA at the concentration down to 9 pM with a wide dynamic range of 6 orders of magnitude (from 1 × 10−11 M to 1 × 10−6 M) in 30 min, and excellent specificity with discriminating a single base mismatched miRNA sequence. This biosensor exhibits good reproducibility and precision, and has been successfully applied to the detection of miRNA in total RNA samples extracted from human breast adenocarcinoma MCF-7 cells. It, therefore, offers a highly effective alternative approach for miRNA detection in biomedical research and clinical diagnosis. 相似文献
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Lei Pinhua Tang Hua Ding Shijia Ding Xiaojuan Zhu Dan Shen Bo Cheng Quan Yan Yurong 《Mikrochimica acta》2015,182(1-2):289-296
Microchimica Acta - We have developed a sensitive method for the determination of Salmonella by integrating a streptavidinylated aptamer (SA-aptamer) as a signal amplification unit along with a... 相似文献
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Nuo Duan Shijia Wu Changqing Zhu Xiaoyuan Ma Zhouping Wang Ye Yu Yuan Jiang 《Analytica chimica acta》2012
A sensitive luminescent bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus was developed using aptamer-conjugated magnetic nanoparticles (MNPs) for both recognition and concentration elements and using upconversion nanoparticles (UCNPs) as highly sensitive dual-color labels. The bioassay system was fabricated by immobilizing aptamer 1 and aptamer 2 onto the surface of MNPs, which were employed to capture and concentrate S. Typhimurium and S. aureus. NaY0.78F4:Yb0.2,Tm0.02 UCNPs modified aptamer 1 and NaY0.28F4:Yb0.70,Er0.02 UCNPs modified aptamer 2 further were bond onto the captured bacteria surface to form sandwich-type complexes. Under optimal conditions, the correlation between the concentration of S. Typhimurium and the luminescent signal was found to be linear within the range of 101–105 cfu mL−1 (R2 = 0.9964), and the signal was in the range of 101–105 cfu mL−1 (R2 = 0.9936) for S. aureus. The limits of detection of the developed method were found to be 5 and 8 cfu mL−1 for S. Typhimurium and S. aureus, respectively. The ability of the bioassay to detect S. Typhimurium and S. aureus in real water samples was also investigated, and the results were compared to the experimental results from the plate-counting methods. Improved by the magnetic separation and concentration effect of MNPs, the high sensitivity of UCNPs, and the different emission lines of Yb/Er- and Yb/Tm-doped NaYF4 UCNPs excited by a 980 nm laser, the present method performs with both high sensitivity and selectivity for the two different types of bacteria. 相似文献
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Herein, insoluble multiwalled carbon nanotubes (MWNTs) were dispersed into N,N-dimethylformamide (DMF) via ultrasonication, resulting in a stable and homogeneous MWNTs suspension. After evaporation of DMF, the surface of glassy carbon electrode was successfully coated with MWNTs film, as confirmed from scanning electron microscopy measurements. In pH 7 phosphate buffer, an irreversible oxidation peak was observed for magnolol, and the peak currents greatly increased on MWNTs film surface. The influences of pH value, amount of MWNTs and accumulation conditions were studied. Based on the remarkable enhancement effect of MWNTs, a new electrochemical sensor with high sensitivity was developed for magnolol. The linear range was from 5 μg?L?1 to 1 mg?L?1, and the detection limit was 2 μg?L?1 (7.51?×?10?9?M) after a 3-min accumulation. This novel sensor was successfully used to detect the content of magnolol in Chinese traditional medicines, and the recovery was over the range from 98.1 to 99.1 %. 相似文献
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