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Fluorescence detection of Escherichia coli on mannose modified ZnTe quantum dots
摘要： Rapid detection and identification of Escherichia coli (E.coli) is essential to prevent its quickly spread. In this study, a novel fluorescence probe based on ZnTe quantum dots (QDs) modified by mannose (MAN) had been prepared for the determination of E.coli. The results showed that the obtained QDs showed excellent selectivity toward E.coli, and presented a good linearity in range of 1.0 × 105~1.0 × 108 CFU/mL. The optimum fluorescence intensity for detecting E.coli was found to be at pH 7.0 with a temperature of 25 oC and incubation time of 20 min. Under these optimum conditions, the detection limit of E.coli was 4.6 × 104 CFU/mL. The quenching was discussed to be a static quenching procedure, which was proved by the quenching efficiency of QDs decreased with the temperature increasing.
关键词： Fluorescence intensity,Mannose,ZnTe quantum dots,Probe,Escherichia coli
更新于2025-09-11 14:15:04
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Photoinduced Antibacterial Activity of the Essential Oils from Eugenia brasiliensis Lam and Piper mosenii C. DC. by Blue Led Light
摘要： The objective of this work was to evaluate the phytochemical composition and the antibacterial and antibiotic-modulating activities of the essential oils of Eugenia brasiliensis Lam (OEEb) and Piper mosenii C. DC (OEPm) singly or in association with blue LED (Light-emitting diode) light. The antibacterial and antibiotic-modulatory activities of the essential oils on the activity of aminoglycosides were evaluated to determine the minimum inhibitory concentration (MIC, μg/mL) in the presence or absence of exposure to blue LED light. The chemical analysis showed α-pinene and bicyclogermacrene as major constituents of OEPm, whereas α-muurolol was the main compound of OEEb. Both OEEb and OEPm showed MIC ≥ 512 μg/mL against the strains under study. However, the association of these oils with the blue LED light enhanced the action of the aminoglycosides amikacin and gentamicin. In conclusion, the association of aminoglycosides with the blue LED light and essential oils was effective against resistant bacteria.
关键词： blue light,Piper mosenii,bacterial resistance,Eugenia brasiliensis,Staphylococcus aureus,Escherichia coli
更新于2025-09-11 14:15:04
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Experimental study on inactivation of <i>Escherichia coli</i> by atmospheric pressure non-equilibrium plasma combined with photocatalysis
摘要： In order to improve the sterilization effect and energy efficiency of atmospheric pressure non-equilibrium plasma (APNP), a synergistic treatment system of APNP combined with photocatalysis was established to inactivate Escherichia coli. TiO2 is selected as the photocatalyst. The colony counting result indicates that APNP treatment combined with photocatalysis has an enhancement effect on sterilization. The enhancement factor η is up to 80.2%. The SEM images show that 30 s APNP treatment combined with photocatalysis causes greater structural damage than traditional APNP treatment. The discoloration photometric suggests that up to 120% more ROS are produced in APNP combined with photocatalysis. Optical emission spectra show that photocatalysis leads to weakening of the ionization process and thus weakens the plasma discharge. In accordance with the infrared thermal images, temperature rise in APNP combined with photocatalysis is 4 °C lower than that in traditional APNP treatment, which may enlarge the application area of biomedical field.
关键词： Escherichia coli,atmospheric pressure non-equilibrium plasma,photocatalysis,ROS,TiO2,sterilization
更新于2025-09-10 09:29:36
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Fluorescence imaging of <i>Escherichia coli</i> on a rotating optical disk
摘要： We constructed a ?uorescence image from a rotating optical disk sample by aligning laser-scanned results based on positioning marks formed on the disk substrate. When Escherichia coli cells and 0.75-μm-diameter polystyrene beads were placed on the sample surface and a cell staining solution was used, ?uorescence from only E. coli cells was observed in the obtained image. This indicates that E. coli cells can be distinguished from polystyrene beads, an abiotic substance, in one image. A promising utilization of this method is as a sensor for ?nding targets among contaminants on a large area.
关键词： fluorescence imaging,Escherichia coli,sensor,polystyrene beads,optical disk
更新于2025-09-10 09:29:36
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Enhanced biosynthesis of CdS nanoparticles through Arabidopsis thaliana phytochelatin synthase-modified Escherichia coli with fluorescence effect in detection of pyrogallol and gallic acid
摘要： In this work, CdS nanoparticles (CdS NPs) biosynthesized through Arabidopsis thaliana phytochelatin synthase-modified Escherichia coli (CdS/AtPCS1-E. coli) with fluorescence (FL) performance for detection of pyrogallol and gallic acid was investigated. Through expression of the AtPCS1 gene inside E. coli cells by pET28b vector, biosynthesis of CdS NPs was greatly enhanced due to generation of phytochelatins (PCs, (γ-Glu-Cys)n-Gly, n ≥ 2) for efficient capture of Cd2+. The expression of AtPCS1 and concentration of glutathione (GSH) and PCs were detected by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high performance liquid chromatography (HPLC), respectively. The morphology and component were checked through scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). FL effect with different experimental conditions were examined. In addition, it is also applied to determination of pyrogallol and gallic acid. These results revealed that multifunctional PCs could effectively facilitate biosynthesis of CdS NPs with higher yield, better distribution and lower cost while stronger FL intensity could be obtained for quantitative analysis.
关键词： CdS nanoparticles,Escherichia coli,Phytochelatin,Fluorescence performance,Biosynthesis
更新于2025-09-09 09:28:46
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Choosing the right label for single-molecule tracking in live bacteria: side-by-side comparison of photoactivatable fluorescent protein and Halo tag dyes
摘要： Visualizing and quantifying molecular motion and interactions inside living cells provides crucial insight into the mechanisms underlying cell function. This has been achieved by super-resolution localization microscopy and single-molecule tracking in conjunction with photoactivatable fluorescent proteins (PA-FPs). An alternative labelling approach relies on genetically-encoded protein tags with cell-permeable fluorescent ligands which are brighter and less prone to photobleaching than fluorescent proteins but require a laborious labelling process. Either labelling method is associated with significant advantages and disadvantages that should be taken into consideration depending on the microscopy experiment planned. Here, we describe an optimised procedure for labelling Halo-tagged proteins in live Escherichia coli cells. We provide a side-by-side comparison of Halo tag with different fluorescent ligands against the popular photoactivatable fluorescent protein PAmCherry. Using test proteins with different intracellular dynamics, we evaluated fluorescence intensity, background, photostability, and results from single-molecule localization and tracking experiments. Capitalising on the brightness and extended spectral range of fluorescent Halo ligands, we also demonstrate high-speed and dual-colour single-molecule tracking.
关键词： Halo tag,single-molecule tracking,photoactivatable fluorescent protein,Escherichia coli,fluorophores,super-resolution microscopy,DNA-binding proteins
更新于2025-09-04 15:30:14
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Cu-Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity
摘要： Surface contamination by microbes is a major public health concern. A damp environment is one of potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO2) can effectively curb this growing threat. Metal-doped titania in anatase phase has been proven as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu)-doped TiO2 (Cu-TiO2) was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO2 was carried out via sol-gel technique. Cu-TiO2 further calcined at various temperatures (in the range of 500–700 ?C) to evaluate the thermal stability of TiO2 anatase phase. The physico-chemical properties of the samples were characterized through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV–visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO2 was maintained well, up to 650 ?C, by the Cu dopant. UV–vis results suggested that the visible light absorption property of Cu-TiO2 was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasize the introduction of Cu+ and Cu2+ ions by replacing Ti4+ ions in the TiO2 lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9999%) was attained in 30 min of visible light irradiation by Cu-TiO2.
关键词： Staphylococcus aureus,phase transition,antibacterial coatings,photocatalysis,doping,Cu-doped TiO2,Escherichia coli
更新于2025-09-04 15:30:14