ANALYTICA CHIMICA ACTA
·
2019
·
IF 5.256
Huili Tian,Nuo Duan,Shijia Wu,Zhouping Wang
Spermine contamination ranks as one of the food safety issues, it will cause some adverse reactions if the intake of spermine is excessive in human body. So it is of great significance to establish fast and efficient analysis method to detect spermine in foods. In this study, the spermine aptamers with high affinity and specificity were obtained by the capture systematic evolution of ligands by exponential enrichment (Capture-SELEX) technique. Forty-one aptamer sequences were obtained by cloning and sequencing, and were divided into eight families based on homology and secondary structure analysis. The affinity and specificity of candidate aptamers was analyzed by isothermal titration calorimetry (ITC) and fluorescence assay . The aptamers named APJ-6 was picked out as the optimal aptamer that recognizes spermine specifically with the Kd value of 9.648 ± 0.896 nM. In order to verify the practicability of the selected aptamers, the sensitive aptamer-based fluorescene assay was designed. Under optimized conditions, this aptasensor exhibited a low detection limit of 0.052 nM, as well as a linear within the range of 0.1–20 nM. Besides, it has been further applied for the determination of spermine in pork samples and the recoveries ranged from 86.45% to 98.15%, showing its great potential for sensitive analysis in food safety control.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2019
·Vol. 136
·期 45
·48186
·
IF 2.188
Xiaoguang Ying,Anshun Kang,Xiaomei Zhu,Xiao Li
Electrospinning is an important tool for generating continuous fibers with large surface area and high pore ratio. The combination of nanofiber membrane and molecular imprinting can effectively measure specific adsorption of putrescine with coloring procedure. In this work, molecularly imprinted electrospun chromogenic membrane was synthesized with 1,4-butanediol (BDO) as imitate template. Poly(vinyl alcohol) (PVA) is used as spinning solution and ninhydrin as chromogenic agent for visualizing detection of target molecular putrescine. The adsorption concentration on molecularly imprinted polymer is illustrated by blue-purple colored stains and recorded by interactive three-dimensional surface plot of ImageJ. The results indicated that a uniform and bead-free PVA nanofiber was obtained using 10% (w/w) PVA solution, 15 kV voltage, 15 cm spinning distance, and 600 rpm roller speed. Also, the adsorption performance of molecular imprinting chromogenic membrane was investigated in detail, showing a higher adsorption capacity of 33.16 μg cm −2 and maximum imprinting efficiency of 2.30 under the best recognition conditions of 315 μL ninhydrin, 0.25% (w/w) BDO, and 0.4 cm sensing distance, as well as a short adsorption equilibrium time of 40 min. In addition, three amine competitors were discussed to reveal the better selectivity and higher specific recognition ability in the imprinted membrane. HIGHLIGHTS The molecular imprinting and coloring structure is constructed in nanofiber membrane with an enhanced specific surface area. The adsorption on imprinted membrane is visualized by chromogenic reaction between putrescine and ninhydrin to form a three-dimensional interactive surface proceeded using the ImageJ software. The imprinted nanofiber membrane with large area and high pore ratio is applied in detecting target in trace concentration within shortened time. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 48186.
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TALANTA
·
2018
·
IF 4.244
Li Zou,Tingting Li,Ruidi Shen,Shaozhi Ren,Liansheng Ling
A label-free light-up fluorescent sensing strategy using hybridization chain reaction (HCR) amplification and DNA triplex assembly has been developed. Remarkably, the proposed fluorescence assay is successfully applied to the determination of avian influenza A (H7N9) virus DNA and thrombin. Herein, in the presence of targets, the target DNA/initiator triggers a cascade of hybridization events between H1 and H2 that yields nicked double helices analogous to alternating copolymers . With the additions of triplex-forming oligonucleotide (TFO) and berberine , the triplex structures form between HCR products and TFO. Then, a large amount of berberine can bind to the triplex structures and the sensing system exhibits a dramatic increase in the fluorescence intensity at 530 nm. Under optimal conditions, the label-free fluorescent sensing platform shows sensitive responses to H7N9 virus DNA and thrombin in the range of 0.2–100 nM and 0.5–200 nM, respectively. The detection limits of H7N9 virus DNA and thrombin are as low as 0.14 nM and 0.32 nM, respectively. Owing to the simplicity and low cost, the proposed strategy can be used in other biomarkers assays, providing a promising tool for clinical diagnosis and biomedical detection.
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MICROCHIMICA ACTA
·
2018
·Vol. 185
·期 9
·1-9
·
IF 5.705
Wang Jing,Li Haigang,Li Tingting,Ling Liansheng
A one-step, one-tube colorimetric assay is described for the detection of bacterial double-stranded DNA (dsDNA). It utilizes a G-quadruplex DNAzyme produced by an asymmetric polymerase chain reaction (As-PCR) that catalyzes the oxidation of cysteine to form cystine. This results in the formation of oligonucleotide-modified gold nanoparticles via triplex formation, and eventually in a color change from red to blue that occurs within about 10 mins. This can be measured by ratiometric colorimetric (at 525 and 600 nm). The limit of detection (LOD) for the model analyte (dsDNA of Staphylococcus aureus ( S. aureus )) is as low as 0.28 pg per 0.05 mL with a good linear response ranging from 16.0 fg·μL −1 to 1.6 ng·μL −1 . This is much lower than previously reported LODs. The assay is highly selective for S. aureus dsDNA over a range of other bacterial DNAs. Conceivably, it provides an attractive alternative tool for rapid detection of bacterial dsDNA as required in pathogen screening in the food industry.
Schematic presentation of a colorimetric assay for bacterial DNA. It is based on the catalytic activity of a G-quadruplex DNAzyme that is formed by an asymmetric PCR involving triplex DNA formation and gold nanoparticle (AuNPs) aggregation.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2018
·
IF 5.667
Jing Wang,Tingting Li,Haigang Li,Gongke Li,Shixin Wu,Liansheng Ling
AuNPs-DNA probes remain a challenge to recognize the double-stranded DNA (dsDNA) from routine PCR product despite its success in the recognition of the single-stranded (ssDNA) DNA of asymmetry-PCR product. Here, a universal colorimetric PCR biosensor is established with oligonucleotide modified AuNPs by recognizing the dsDNA of PCR product based on triplex DNA formation with the assistance of a triplex DNA intercalator Ru(phen) 2 dppx 2+ . The strategy was applied to detect different length dsDNA, including short dsDNA 1 (49 bp) and long dsDNA 2 (321 bp), both of which had the good linear relationship between the absorbance and the logarithm of the concentration of the targets. Moreover, the limit of detection (LOD) for short and long length dsDNA was 0.5 pM and 0.05 fg, lower than those of the previously reported methods, respectively. This strategy also displayed high selectivity against dsDNA 1 and dsDNA 2. These results demonstrate a potential strategy to detect all length of dsDNA, providing new opportunities in the life science, diagnosis, and medicine.
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BIOMACROMOLECULES
·
2013
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IF 5.371
Yuefang Zhao,Yuting Qin,Yang Liang,Haijuan Zou,Xiao Peng,Huan Huang,Ming Lu,Min Feng
Short interfering RNAs (siRNAs) as chemotherapeutic RNAi agents hold great promise for a significant improvement in cancer therapy. Despite the promise, effective transport of siRNA with minimal side effects remains a challenge. The common problem associated with the low delivery efficiencies of current polycation-based gene delivery systems is their low stability in the presence of salt and serum. In the present study we developed the polyglutamate derivatives (PGS) polyelectrolyte brushes for NF-κB p65 siRNA delivery. The PGS polyelectrolyte brushes/siRNA polyplex was colloidally stable (150 nm diameter) in physiological saline (150 mM NaCl), likely due to the osmotic brushes of PGS. The size-controlled siRNA/PGS polyplex also showed the serum resistance resulting in their efficient cellular uptake was not negatively influenced by the presence of serum. The endothermic profile of ITC, their low values of Gibbs free energy and binding constants Kb under salt conditions provided the direct evidence that PGS polyelectrolyte brushes had a much lower binding affinity for serum proteins, compared with PEI 25KDa. PGS polyelectrolyte brushes delivering NF-κB p65 siRNA achieved efficient down-regulation of NF-κB p65 protein in HeLa cells. The NF-κB p65 down-regulation mediated by PGS polyelectrolyte brushes was more significant than PEI 25KDa and comparable to Lipofectamine 2000. Furthermore, the combination treatment with PGS polyelectrolyte brushes/NF-κB p65 siRNA polyplex and doxorubicin demonstrated synergistic apoptotic and cytotoxic effects on HeLa cancer cells. The high stability in physiological saline and salt-induced serum resistance of PGS polyelectrolyte brushes/siRNA polyplex has potential applications together with standard chemotherapies such as doxorubicin to be a viable method to improve the clinical outcomes in cancer therapies.
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MOLECULAR NEUROBIOLOGY
·
2016
·Vol. 54
·期 1
·392-405
·
IF 5.397
Chen Ying,Huang Liyong,Zhang Huiyong,Diao Xiling,Zhao Shuyang,Zhou Wenke
Mitochondrial dysfunction and subsequent autophagy, which are common features in central nervous system (CNS) disorders, were found to contribute to neuronal cell injury after subarachnoid hemorrhage (SAH). (-)-Epigallocatechin-3-gallate (EGCG), the main biological active of tea catechin, is well known for its beneficial effects in the treatment of CNS diseases. Here, the ability of EGCG to rescue cellular injury and mitochondrial function following the improvement of autophagic flux after SAH was investigated. As expected, EGCG-protected mitochondrial function depended on the inhibition of cytosolic Ca 2+ concentration ([Ca 2+ ] i ) influx via voltage-gated calcium channels (VGCCs) and, consequently, mitochondrial Ca 2+ concentration ([Ca 2+ ] m ) overload via mitochondrial Ca 2+ uniporter (MCU). The attenuated [Ca 2+ ] i and [Ca 2+ ] m levels observed in the EGCG-treated group likely lessened oxyhemoglobin (OxyHb)-induced mitochondrial dysfunction, including mitochondrial membrane potential depolarization, mitochondrial membrane permeability transition pore (mPTP) opening, reactive oxygen species (ROS), and cytochrosome c (cyt c) releasing. Subsequently, EGCG can restore the disrupted autophagy flux after SAH both at the initiation and formation stages by regulating Atg5 , LC3B , and Becn-1 ( Beclin-1 ) mRNA expressions. Thus, precondition EGCG resulted in autophagosomes and more autolysosomes compared with SAH group. As a result, EGCG pre-treatment increased the neurological score and decreased cell death. This study suggested that the mitochondrial dysfunction and abnormal autophagy flux synergistically contribute to SAH pathogenesis. Thus, EGCG can be regarded as a new pharmacological agent that targets both mitochondria and altered autophagy in SAH therapy.
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CARBOHYDRATE POLYMERS
·
2017
·
IF 4.811
Xiaoyi Huang,Xiaoxi Li,Ling Chen,Lin Li
This study aims at developing starch based gene carriers with low cytotoxicity and high transfection efficiency. Starch molecules with molecular weight of about 50 kDa were cationically modified by spermine to obtain spermine modified starch (SMS) based gene carriers. Plasmid pAcGFP1-C1 (pDNA) was chosen as the model gene material and formed self-assembly nanocomplexes with SMS. The cytotoxicity and transfection efficiency of SMS/pDNA complexes were tested in HepG2 cell lines. Results showed that SMS/pDNA complexes formed by SMS-DS3 with the highest primary amine content (1.17 μmol mg −1 ) and pDNA at the weight ratio of 25 displayed the highest transfection efficiency (∼40%) with low cytotoxicity. Dynamic Light Scattering (DLS) and Small Angel X-ray Scattering (SAXS) investigation under simulated acidified endosomal environments (pH 5.0–7.4) revealed that SMS-DS3/pDNA complexes (∼180 nm) with moderately compact structures within acidic environments (i.e. no significant particle size changes, slightly shrunken shapes) showed superior transfection efficiency.
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INTERNATIONAL JOURNAL OF PHARMACEUTICS
·
2016
·
IF 3.994
Zhongjuan Wang,Haijuan Zou,Zirui Wang,Jiamin Wu,Zhongsheng Xia,Min Feng
RNA interfere (RNAi)-based technology holds great promise in cancer treatment. The use of small interfering RNA (siRNA), however, is hampered by its low delivery efficiency in vivo when they are diluted in blood biofluids and in the presence of serum and salt. In this study, we developed the polyglutamate derivative polymer brush, poly(ethyleneglycol) monomethyl ether-b-polyglutamate-g-spermine (mPEG-b-PG-g-spermine, PPGS), which could efficiently deliver survivin-siRNA under ultra-high dilution and in the presence of salt (NaCl 150 mM) and serum (10% FBS), most likely due to its PEG-shelled polymer brush structure. On the contrary, aggregation occurred when PEI/siRNA polyplex dispersed in saline and serum-containing media and PEI polyplex dissociated after making a 256-fold dilution. PPGS/si-survivin polyplex exhibited high cellular uptake efficiency and efficiently down-regulated the expression of survivin mRNA in the cisplatin-resistance of non-small cell human lung adenocarcinoma (A549/DDP) cells in the presence of serum. However, either PEI polyplex or Lipofectmine 2000 complex was unstable in serum and salt-containing media and at high dilution rates, which resulted in their dramatical decrease of cellular uptake and gene-silencing efficiency in these conditions. The PPGS/si-survivin polyplex also exhibited synergistic effects of killing the cancer cells by combination treatment with cisplatin . Therefore, the PPGS gene carrier showed great potential in systemic siRNA delivery, and its combination with chemotherapeutic drug is promising in treating drug resistant cancers.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2017
·
IF 2.536
Yonghui Nie,Yuanjie Teng,Pan Li,Wenhan Liu,Qianwei Shi,Yuchao Zhang
A novel label-free aptamer surface-enhanced Raman scattering (SERS) sensor for trace malathion residue detection was proposed. In this process, the binding of malathion molecule with aptamer is identified directly. The silver nanoparticles modified with positively charged spermine served as enhancing and capture reagents for the negatively charged aptamer. Then, the silver nanoparticles modified by aptamer were used to specifically capture the malathion. The SERS background spectra of spermine, aptamer, and malathion were recorded and distinguished with the spectrum of malathion–aptamer. To enhance the characteristic peak signal of malathion captured by the aptamer, the aggregate reagents (NaCl, KCl, MgCl 2 ) were compared and selected. The selectivity of this method was verified in the mixed-pesticide standard solution, which included malathion, phosmet , chlorpyrifos-methyl, and fethion. Results show that malathion can be specifically identified when the mixed-pesticide interferences existed. The standard curve was established, presenting a good linear range of 5 × 10 − 7 to 1 × 10 − 5 mol·L − 1 . The spiked experiments for tap water show good recoveries from 87.4% to 110.5% with a relative standard deviation of less than 4.22%. Therefore, the proposed label-free aptamer SERS sensor is convenient, specifically detects trace malathion residues, and can be applied for qualitative and quantitative analysis of other pesticides.
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TALANTA
·
2016
·
IF 4.035
Meng Li Liu,Bin Bin Chen,Ze Xi Liu,Cheng Zhi Huang
Though many methods of detecting 2,4,6-trinitrophenol (TNP) mainly have been developed recent years, quantification of TNP in environmental matrixes still faces up to great challenges because all the nitroaromatic explosives reveal highly similar chemical structure. In the present work, we have developed a selective and sensitive method for detection of TNP by amorphous photoluminescent carbon nanodots (CNDs), which are prepared through a simple hydrothermal route using spermine and m-phenylenediamine (MPD) as precursors. The as-prepared CNDs are found to show blue–green photoluminescence, excitation-wavelength independence, and excellent chemical and optical stability. Owing to the strong characteristic absorption of TNP at 356 nm ( ε =1.048×10 4 cm −1 M −1 ), which has a good spectral overlap with the excitation band of CNDs, the fluorescence intensity of CNDs at 490 nm is linearly quenched with the adding concentration of TNP in the range of 0.1–100 μM. The developing assay based on inner filter effect (IFE) mechanism for the detection of TNP is selective and convenient, showing that the as-prepared CNDs have applicable prospect in the concept of simplicity and specificity in analytical chemistry .
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ANALYST
·
2016
·Vol. 141
·期 20
·5829-5834
·
IF 4.033
Xiangmin Miao,Zongbing Li,Liansheng Ling
An ultrasensitive fluorescent platform for sequence-specific recognition of double-stranded DNA (dsDNA) based on the quenching of gold nanoparticles (AuNPs) to a fluorophore labeled DNA probe was developed. The target dsDNA could hybridize with the loop portion of the molecular beacon (MB) to form a triplex DNA structure and opened the “stem–loop” structure of the MB; such triplex DNA was used as an assistant probe (AP). Meanwhile, a fluorophore labeled DNA-AuNP probe that contained a specific enzyme cleavage site was introduced and its fluorescence signal was efficiently quenched due to the vicinity of the fluorophore to the AuNP surface. Such a DNA-AuNP probe could hybridize with the 5′ stem portion of the MB in the AP to form duplex DNA strands that contained a specific enzyme cleavage site for the nicking enzyme assisted cleavage reaction, and resulted in the release of the fluorophore from the AuNP surface and the recovery of the fluorescence signal. Because the AP remains intact during such a cleavage process, it could be reused to hybridize with the next DNA-AuNP probe and trigger the nicking nuclease assisted signal amplification. Under optimal conditions, a low detection limit of 3.8 pM was obtained for dsDNA detection, and the assay has high sequence specificity for dsDNA detection.
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