ANALYTICAL CHEMISTRY
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2020
·
IF 6.785
Xuan Sun,Yu Wang,Lu Zhang,Sha Liu,Man Zhang,Jiang Wang,Baoan Ning,Yuan Peng,Jing He,Yonggang Hu,Zhixian Gao
Escherichia coli O157:H7 has been reported as an important pathogenic bacteria causing serious infection and economic loss. However, detection of Escherichia coli O157:H7 needs improvement, given its current complexity and sensitivity. Herein, we attempt to build a fluorescence sensing method to detect Escherichia coli O157:H7 with easy operation and high efficiency. The target virulence gene sequences are recognized and cleaved by the CRISPR-Cas9 system, and trigger strand displacement amplification and rolling circle amplification. After amplification reactions, massive products can hybridize with the probes, the fluorescence of which are quenched based on a metal–organic framework platform, leading to the fluorescence recovery at typical excitation/emission wavelengths of 480/518 nm. This method exhibits high sensitivity with the detection limit at 4.0 × 101 CFU mL–1 and a wide range from 1.3 × 102 CFU mL–1 to 6.5 × 104 CFU mL–1. Meanwhile, this assay also shows significant specificity and applies to practical samples with high accuracy. Therefore, our method would have great potential application in bacterial detection, food safety monitoring, or clinical diagnostics.
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CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Zexiao Zheng,Juhua He,Chencheng Dong,Irene M.C. Lo
A new photoelectrochemical (PEC) system by means of adding sodium sulfite (Na 2 SO 3 ) was developed to treat sewage. The PEC system simultaneously promoted pharmaceuticals and personal care products (PPCPs) degradation, H 2 evolution and E. coli disinfection using an optimized, visible–light driven BiVO 4 photoanode. The PEC reactions were first carried out in 1.5 mM Na 2 SO 3 electrolyte. 92.3% of 2 ppm benzophenone-3 (BZP) was degraded, and 115.36 μmol of H 2 was produced in 90 min at 1.0 V vs. Ag/AgCl, which was a significant improvement over cases where the electrolyte was either Na 2 SO 4 or NaCl. The sulfite ions were first activated by holes and then converted into sulfate radicals, which played a dominant role in the degradation of BZP. As the holes were caught by the sulfite, charge separation was also enhanced, increasing H 2 evolution. The PEC reactions were also used to treat real sewage, in which case an 82% improvement in the rate constant of BZP degradation, 60% increase of H 2 evolution, and 0.78 log enhancement of E. coli disinfection were achieved by adding 1.5 mM Na 2 SO 3. The system was also feasible to degrade various PPCPs, and showed excellent reusability and stability, proving its great potential in sewage treatment.
研究领域:
环境科学
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污水处理
·
光催化材料
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JOURNAL OF ALLOYS AND COMPOUNDS
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2021
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IF 5.316
Shiben Liu,Xiaohui Jiang,Geoffrey I.N. Waterhouse,Zhi-Ming Zhang,Liang-min Yu
A novel ternary PPy/P-C 3 N 4 /r-GO visible light-driven photocatalyst was fabricated via chemical polymerization of pyrrole in the presence of protonated-C 3 N 4 /reduced graphene oxide (P-C 3 N 4 /r-GO). The resulting PPy/P-C 3 N 4 /r-GO composite showed excellent photocatalytic performance under visible light for brilliant red dye (X3B) degradation and E. coli inactivation. An X3B degradation efficiency of 98% was achieved in 60 min, and an E. coli removal efficiency of 100% achieved in 90 min. Moreover, PPy/P-C 3 N 4 /r-GO displayed good recycling performance, with 90% efficiency retained over 5×3B photodegradation cycles. A plausible photocatalytic mechanism for the PPy/P-C 3 N 4 /r-GO composites was proposed, where p-n heterojunctions formed between P-C 3 N 4 and PPy effective separate charges (photoexcited electrons accumulating in the conduction band of P-C 3 N 4 , holes accumulating in the valence band of PPy), with r-GO acting as an electron acceptor and trap. The valence band holes in P-C 3 N 4 directly oxidize X3B, whereas conduction band electrons react with O 2 to generate reactive oxygen species (superoxide and hydroxide radicals) which also degrade X3B and can inactivate E. coli . This work thus introduces an efficient metal-free ternary photocatalyst system for environmental applications.
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ENVIRONMENTAL RESEARCH
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2020
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IF 5.715
Jibin An,Yanlin Li,Wei Chen,Guoqiang Li,Jiahong He,Huixia Feng
Metal-organic frameworks (MOFs) are emerging class of porous materials that attracted tremendous attention as eco-friendly photocatalysts. However, poor charge separation in most MOFs largely thwarts their photocatalytic performance. In this work, Materials of Institut Lavoisier-100(Fe) (MIL-100 (Fe)) based on iron mesh was successfully fabricated by in situ growth. MIL-100(Fe) doped with polyaniline, namely MIL-100(Fe)/PANI, were then fabricated by galvanostatic deposition followed by annealing. Compared to pure MIL-100(Fe), MIL-100(Fe)/PANI composites exhibited excellent photocatalytic performances towards Thiamphenicol (TAP) degradation and Escherichia coli ( E. Coli .) inactivation. The apparent rate constant, k , for TAP elimination of the MIL-100(Fe)/PANI composites with H 2 O 2 is approximately 3 times as high as that of pure MIL-100(Fe). The electrochemical studies showed enhanced photocatalytic performances, which can be attributed to the electronic conductivity of PANI polymers. Quenching experiments, fluorescent tests and electron paramagnetic resonance (EPR) all suggested ⋅O 2 − , e − , ⋅OH and h + as reactive oxidizing species (ROSs) involved in the photocatalytic process, where ⋅OH played the predominant ROSs. The transformation products of TAP were also isolated and characterized by high-resolution mass spectrometry, and transformation pathways of TAP under Vis/MIL-100(Fe)/PANI/H 2 O 2 were tentatively clarified based on involved intermediates. Herein, MOFs conjugated conductive polymers nanocomposites look promising as efficient photocatalysts for organic pollutants degradation and bacteria inactivation. This work could offer novel strategies for the development of heterojunction composites with enhanced photocatalytic performances for better environmental remediation.
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NANOTECHNOLOGY
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2020
·Vol. 31
·期 39
·395702
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IF 3.551
Lixia Zhang,Zishu Zhang,Zhiwen Gao,Yan Xie,Shuang Shu,Yuee Ke,Yu Wang,Bin Deng,Ruijin Yu,Huiling Geng
A simple method was developed to prepare fluorescent nitrogen/boron-doped carbon dots (N,B-CDs) in the gram scale. The results showed that the CDs exhibited blue photoluminescence (PL) under 365 nm ultraviolet radiation and excitation-dependent emission. Heteroatoms entered the CDs to enhance the photochemical properties, and their positive properties can be attributed to the presence of guanidino group and functionalized with boronic acid for realizing their utilization in certain applications. These materials could be applied to monitor Fe3+ via static PL quenching, yielding a limit of detection (LOD) of 0.74 μM. Furthermore, the charged and boronic acid groups on the prepared N,B-CDs enabled their use as recognition elements to bind with the bacteria through electrostatic interaction and allowed covalent interactions to form the corresponding boronate ester with E. coli (E. coli) bacterial membrane. This method could satisfy a linear range of 102–107 with LOD of 165 cfu ml−1 for E. coli. This method was applied for the determination of E. coli in tap water and orange juice samples, and satisfactory results were obtained.
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RSC Advances
·
2019
·Vol. 9
·期 4
·2325-2331
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IF 3.049
Yitong Chen,Baodi Ma,Songshuang Cao,Xiaomei Wu,Yi Xu
The production of (S)-N-boc-3-hydroxy piperidine (NBHP) via asymmetric bioreduction of 1-boc-3-piperidinone with reductase is impeded by the need for expensive coenzymes NAD(P)H. In order to regenerate the coenzyme in situ, the gene of alcohol dehydrogenase from Thermoanaerobacter brockii and glucose dehydrogenase from Bacillus subtilis were ligated into the multiple cloning sites of pRSFDuet-1 plasmid to construct the recombinant Escherichia BL21 (DE3) that co-expressing alcohol dehydrogenase and glucose dehydrogenase. Different culture conditions including the medium composition, inducer and pH etc were systematically investigated to improve the enzyme production. The enzyme activity was increased more than 11-fold under optimal culture condition, from 12.7 to 139.8 U L−1. In the further work, the asymmetric reduction of 1-boc-3-piperidinone by whole cells of recombinant E. coli was systematic optimized to increase the substrate concentration and reaction efficiency. At last, S-NBHP (>99% ee) was prepared at 500 mM substrate concentration without external addition of cofactors. The conversion of S-NBHP reached 96.2% within merely 3 h, corresponding a high space-time yield around 774 g L−1 d−1. All these results demonstrated the potential of recombinant E. coli BL21 (DE3) coupled expressing alcohol dehydrogenase and glucose dehydrogenase for efficient synthesis of S-NBHP.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2014
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IF 2.002
Jianhan Lin,Min Li,Yanbin Li,Qi Chen
Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody–antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 µg/ml and 100 µg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 10 2 to 10 5 cfu/ml. No obvious interferences from non-target foodborne pathogens, such as Salmonella Typhimurium and Listeria innocua , were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are practical for rapid screening applications; however the 30 nm magnetic particles are preferable for specific detection applications. This immunomagnetic bioseparator can be integrated with either conventional culture methods or some rapid detection methods, such as biosensors and PCR, for more sensitive detection of foodborne pathogens.
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TALANTA
·
2014
·
IF 3.511
Xinai Zhang,Fan Zhang,Hongyin Zhang,Jianzhong Shen,En Han,Xiaoya Dong
In this paper, we report an amplified electrochemical immunoassay for Escherichia coli as indicator bacteria relevant to the quality of dairy product using the functionalized gold nanorod-based labels ({ d Ab–AuNR–FCA}). The { d Ab–AuNR–FCA} labels were designed by exploiting silica-functionalized gold nanorods (AuNR@SiO 2 ) as the carriers for immobilization of detection antibody ( d Ab) and ferrocenecarboxylic acid (FCA), in which d Ab was used for recognition of E. coli and FCA tags served as signal-generating molecule. Greatly amplified signal was achieved in the sandwich-type immunoassay when enormous FCA linked to AuNR@SiO 2 . Compared with the commercially available { d Ab–FCA}, the { d Ab–AuNR–FCA} labels exhibited a better performance for E. coli assay due to the advantages of AuNR@SiO 2 as carriers. Under optimal experimental conditions, it showed a linear relationship between the peak current of FCA and the logarithmic value of E. coli concentration ranging from 1.0×10 2 to 5.0×10 4 cfu mL −1 with a detection limit of 60 cfu mL −1 ( S / N =3), and the electrochemical detection of E. coli could be achieved in 3 h. Moreover, the proposed strategy was used to determine E. coli in dairy product (pure fresh milk, yogurt in shelf-life, and expired yogurt), and the recoveries of standard additions were in the range of 95.1–106%. This proposed strategy exhibited rapid response, high sensitivity and specificity for E. coli assay in dairy product, and could become a promising technique to estimate the quality of dairy product.
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ANALYST
·
2014
·Vol. 140
·期 2
·551-559
·
IF 3.906
Yuna Guo,Yu Wang,Su Liu,Jinghua Yu,Hongzhi Wang,Min Cui,Jiadong Huang
A novel electrochemical immunosensor assay (EIA) for highly sensitive and specific detection of Escherichia coli O157:H7 has been developed. This immunosensor is constructed by the assembly of capture antibody on SG–PEDOT–AuNPs composites modified glass carbon electrode. In the presence of target E. coli O157:H7, horseradish peroxidase (HRP)-labeled antibody is captured on the electrode surface to form a sandwich-type system via the specific identification. As a result, E. coli O157:H7 detection is realized by outputting a redox current from electro-reduction of hydrogen peroxide reaction catalyzed by HRP. In our assay, the combination of the unique properties of sulfonated graphene (SG) and gold nanoparticles (AuNPs) can not only accelerate electron transfer on electrode interface, but also provide an excellent scaffold for the conjugation of capture antibody that significantly improves the target capture efficiency and enhances the sensitivity of the biosensor. The results reveal the calibration plot obtained for E. coli O157:H7 is approximately linear from 7.8 × 10–7.8 × 106 colony-forming unit (cfu) mL−1 with the limit of detection of 3.4 × 10 cfu mL−1. In addition, the biosensor has been successfully applied to the quantitative assay of E. coli O157:H7 in synthetic samples (spring water and milk). Hence, the developed electrochemical-based immunosensor might provide a useful and practical tool for E. coli O157:H7 determination and related food safety analysis and clinical diagnosis.
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CATALYSIS LETTERS
·
2025
·Vol. 155
·期 4
·1-10
·
IF 2.4
Cao Songshuang,Wu Xiaomei,Ma Baodi,Xu Yi
Aliphatic chiral secondary alcohols are important chiral intermediates widely used in the synthesis of drugs and fine chemicals. The whole cells of recombinant E. coli co-expressing alcohol dehydrogenase and glucose dehydrogenase were used to catalyze the asymmetric reduction of three fatty ketones without the addition of exogenous cofactors. The reaction medium and reaction conditions were systematically studied. As expected, the kinds of co-solvents, the molar ratio of glucose/substrate, temperature, pH and cell amount have important influence on the reaction. Under the optimal condition (glucose at 1.5 times substrate concentration, isopropanol at 2%, PBS (0.1 M, pH 8.0), and 45℃), the cells co-expressing both enzymes efficiently catalyzed the asymmetric reduction of three fatty ketones to the corresponding ( S )-fatty alcohols. The conversion and ee value of the products were both greater than 99% after 8 h reaction at 1 M of substrate concentration, and the space-time yield was between 346 ~ 470 g/(L·d). All the products can be obtained on gram scale. The results indicated that this method has potential application value in the efficient and green synthesis of aliphatic chiral secondary alcohols. Graphical
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MICROCHIMICA ACTA
·
2025
·Vol. 192
·期 9
·1-14
·
IF 5.3
Cao Xiaodong,Zhang Chenlu,Gao Yu,Yu Weina,Liu Chao,He Shudong,Sun Hanju,Ye Yongkang
Foodborne pathogens are a leading cause of food safety incidents. Here, we developed a highly sensitive dual-channel biosensor for the parallel electrochemical detection of Salmonella typhimurium ( S. typhimurium ) and Escherichia coli ( E. coli ) O157:H7 using bimetallic metal–organic framework (BMOF)-based signal nanotags. The BMOF-based nanotags were synthesized by functionalizing gold nanoparticle-doped CuZr-MOF with signal DNA sequences sDNA1 (forming sDNA1-AuNPs@CuZr-MOF nanotag) and PbZr-MOF with signal DNA sequence sDNA2 (forming sDNA2-AuNPs@PbZr-MOF nanotag). The biosensing platform was constructed using two glassy carbon electrodes (GCEs). Each GCE was sequentially modified, first with electrodeposited gold nanoparticles (depAu) and then with the corresponding capture DNA sequences (cDNA1 for channel 1 or cDNA2 for channel 2). Target detection was achieved on the sensing interface via sandwich hybridization: in channel 1, the invA gene of S. typhimurium (tDNA1) was recognized by both cDNA1 on the sDNA1-AuNPs@CuZr-MOF nanotag; similarly, in channel 2, the eaeA gene of E. coli O157:H7 (tDNA2) was recognized by both cDNA2 and sDNA2 on the sDNA2-AuNPs@PbZr-MOF nanotag. Leveraging the high stability and ease of surface modification of UiO-66 (Zr-MOF), along with the enhanced electrochemical oxidation signals from the introduced secondary metal ions (Cu 2+ and Pb 2+ ) in Zr-MOF framework, the biosensor achieved parallel detection with wide linear ranges (3.5 to 3.5 × 10 5 CFU mL −1 for S. typhimurium , and 2.2 to 2.2 × 10 5 CFU mL −1 for E. coli O157:H7) and low detection limit (LODs of 0.54 CFU mL −1 and 0.80 CFU mL −1 , respectively). Furthermore, the fabricated biosensor demonstrated excellent reproducibility, selectivity, and stability, highlighting great potential for practical use in monitoring foodborne pathogens. Graphical
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Frontiers in Chemistry
·
2022
·
IF 5.545
Wang Huan,Fan Yanmiao,Yang Qiaoli,Sun Xiaoyu,Liu Hao,Chen Wei,Aziz Ayesha,Wang Shenqi
Redox activity is an important indicator for evaluating electrochemical biosensors. In this work, we have successfully polymerized indole-5-carboxylic acid into poly-5-carboxyindole nanomaterials (PI-5-CA), using its superior redox activity, and introduced carboxylated single-walled carbon nanotubes (C-SWCNTs) to synthesize a composite material. Finally, a synthesized composite material was used for the modification of the glass carbon electrode to fabricate the PI-5-CA/C-SWCNTs/GCE-based immunosensor and was successfully applied for the sensitive detection of E. coli O157:H7. The fabricated immunosensor exhibited an outstanding electrocatalytic activity toward the detection of E. coli O157:H7 with a remarkably lowest limit of detection (2.5 CFU/ml, LOD = 3 SD/k, n = 3) and has a wide linear range from 2.98×101 to 2.98×107 CFU/ml. Inspired from the excellent results, the fabricated electrode was applied for the detection of bacteria from real samples (water samples) with a good recovery rate (98.13–107.69%) as well as an excellent stability and specificity. Owing to its simple preparation, excellent performance, and detection time within 30 min, our proposed immunosensor will open a new horizon in different fields for the sensitive detection of bacteria from real samples.
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