SERS-based Au@Ag NPs Solid-phase Substrate Combined with Chemometrics for Rapid Discrimination of Multiple Foodborne Pathogens

AbstractA solid-phase photochemical method produces Au–Ag alloy nanoparticles (NPs) with a sharp size distribution and varying composition in AgBr crystals (Au–Ag@AgBr). These features render Au–Ag@AgBr promising as a material for the plasmonic photocatalyst further to provide a possibility of elucidating the action mechanism due to the optical tunability. This study shows that the visible-light activity of Au–Ag@AgBr for degradation of model water pollutant is very sensitive to the alloy composition with a maximum at the mole percent of Au to all Ag in AgBr (y) = 0.012 mol%. Clear positive correlation is observed between the photocatalytic activity and the quality factor defined as the ratio of the peak energy to the full width at half maximum of the localized surface plasmon resonance band. This finding indicates that Au–Ag@AgBr works as a local electromagnetic field enhancement-type plasmonic photocatalyst in which the Au–Ag NPs mainly promotes the charge separation. This conclusion was further supported by the kinetic analysis of the light intensity-dependence of external quantum yield.

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Lactolisterin BU, a Novel Class II Broad-Spectrum Bacteriocin from Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4

Applied and Environmental Microbiology ◽

10.1128/aem.01519-17 ◽

2017 ◽

Vol 83 (21) ◽

Cited By ~ 9

Author(s):

Jelena Lozo ◽

Nemanja Mirkovic ◽

Paula M. O'Connor ◽

Milka Malesevic ◽

Marija Miljkovic ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Listeria Monocytogenes ◽

Lactococcus Lactis ◽

Foodborne Pathogens ◽

Broad Spectrum ◽

Solid Phase ◽

Food Spoilage ◽

Content Type ◽

Strong Antimicrobial Activity

ABSTRACT Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4 produces a novel bacteriocin, lactolisterin BU, with strong antimicrobial activity against many species of Gram-positive bacteria, including important food spoilage and foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, Bacillus spp., and streptococci. Lactolisterin BU was extracted from the cell surface of BGBU1-4 by 2-propanol and purified to homogeneity by C18 solid-phase extraction and reversed-phase high-performance liquid chromatography. The molecular mass of the purified lactolisterin BU was 5,160.94 Da, and an internal fragment, AVSWAWQH, as determined by N-terminal sequencing, showed low-level similarity to existing antimicrobial peptides. Curing and transformation experiments revealed the presence of a corresponding bacteriocin operon on the smallest plasmid, pBU6 (6.2 kb), of strain BGBU1-4. Analysis of the bacteriocin operon revealed a leaderless bacteriocin of 43 amino acids that exhibited similarity to bacteriocin BHT-B (63%) from Streptococcus ratti, a bacteriocin with analogy to aureocin A. IMPORTANCE Lactolisterin BU, a broad-spectrum leaderless bacteriocin produced by L. lactis subsp. lactis bv. diacetylactis BGBU1-4, expresses strong antimicrobial activity against food spoilage and foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, Bacillus spp., and streptococci. Lactolisterin BU showed the highest similarity to aureocin-like bacteriocins produced by different bacteria. The operon for synthesis is located on the smallest plasmid, pBU6 (6.2 kb), of strain BGBU1-4, indicating possible horizontal transfer among producers.

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Assessment of Antimicrobial Activity, Mode of Action and Volatile Compounds of Etlingera pavieana Essential Oil

Molecules ◽

10.3390/molecules25143245 ◽

2020 ◽

Vol 25 (14) ◽

pp. 3245

Author(s):

Porawan Naksang ◽

Sasitorn Tongchitpakdee ◽

Kanjana Thumanu ◽

Maria Jose Oruna-Concha ◽

Keshavan Niranjan ◽

...

Keyword(s):

Antimicrobial Activity ◽

Chemical Composition ◽

Volatile Compounds ◽

Foodborne Pathogens ◽

Solid Phase ◽

Gas Chromatography Mass Spectrometry ◽

Dilution Method ◽

Membrane Composition ◽

Gram Positive ◽

Gram Positive Bacteria

Etlingera pavieana (Pierre ex Gagnep.) R.M.S. is a rhizomatous plant in the Zingiberaceae family which could be freshly eaten, used as a condiment or as a traditional remedy. Our work investigated the chemical composition and antimicrobial activity of the E. pavieana essential oils extracted from the rhizome (EOEP). We extracted the EOEP from the rhizome by hydrodistillation and analyzed the chemical composition by headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry (HS-SPME-GC/MS). A total of 22 volatile compounds were identified where trans-anethole (78.54%) and estragole (19.36%) were the major components in the EOEP. The antimicrobial activity of EOEP was evaluated based on the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values using the broth dilution method and enumerating cell death overtime. Our work shows that the EOEP exhibits potent antibacterial activity against foodborne pathogenic Gram-positive bacteria, namely Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes in the range of 0.1–0.3% (v/v). We further investigated the mechanism of EOEP inhibition using Synchrotron Fourier transformation infrared (FTIR) microspectroscopy. Here, we show significant differences in DNA/nucleic acid, proteins and cell membrane composition in the bacterial cell. To conclude, EOEP exhibited antimicrobial activity against foodborne pathogens, especially the Gram-positive bacteria associated with ready-to-eat (RTE) food and, thus, has the potential to serve as a natural preservative agent in RTE products.

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Silver Nanoparticles against Foodborne Bacteria. Effects at Intestinal Level and Health Limitations

Microorganisms ◽

10.3390/microorganisms8010132 ◽

2020 ◽

Vol 8 (1) ◽

pp. 132 ◽

Cited By ~ 17

Author(s):

Irene Zorraquín-Peña ◽

Carolina Cueva ◽

Begoña Bartolomé ◽

M. Victoria Moreno-Arribas

Keyword(s):

Silver Nanoparticles ◽

Foodborne Pathogens ◽

Food Processing ◽

Food Industry ◽

Antimicrobial Agents ◽

Current Knowledge ◽

Dietary Exposure ◽

Food Control ◽

Ag Nps ◽

The Impact

Foodborne diseases are one of the factors that endanger the health of consumers, especially in people at risk of exclusion and in developing countries. The continuing search for effective antimicrobials to be used in the food industry has resulted in the emergence of nanotechnology in this area. Silver nanoparticles (Ag-NPs) are the nanomaterial with the best antimicrobial activity and therefore, with great potential of application in food processing and packing. However, possible health effects must be properly addressed to ensure food safety. This review presents a detailed description on the main applications of Ag-NPs as antimicrobial agents for food control, as well as the current legislation concerning these materials. Current knowledge about the impact of the dietary exposure to Ag-NPs in human health with special emphasis on the changes that nanoparticles undergo after passing through the gastrointestinal tract and how they alter the oral and gut microbiota, is also summarized. It is concluded that given their potential and wide properties against foodborne pathogens, research in Ag-NPs is of great interest but is not exempt from difficulties that must be resolved in order to certify the safety of their use.

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Solid-phase immunoelectron microscopy for rapid diagnosis of enteroviruses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111240 ◽

1984 ◽

Vol 42 ◽

pp. 226-227 ◽

Cited By ~ 1

Author(s):

K. Pegg-Feige ◽

F. W. Doane

Keyword(s):

Electron Microscopy ◽

Cell Culture ◽

Immunoelectron Microscopy ◽

Detection Method ◽

Solid Phase ◽

Protein A ◽

Plant Viruses ◽

Rapid Diagnosis ◽

Virus Diagnosis ◽

Antiviral Antibody

Immunoelectron microscopy (IEM) applied to rapid virus diagnosis offers a more sensitive detection method than direct electron microscopy (DEM), and can also be used to serotype viruses. One of several IEM techniques is that introduced by Derrick in 1972, in which antiviral antibody is attached to the support film of an EM specimen grid. Originally developed for plant viruses, it has recently been applied to several animal viruses, especially rotaviruses. We have investigated the use of this solid phase IEM technique (SPIEM) in detecting and identifying enteroviruses (in the form of crude cell culture isolates), and have compared it with a modified “SPIEM-SPA” method in which grids are coated with protein A from Staphylococcus aureus prior to exposure to antiserum.

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Application of solid-phase immune electron microscopy to study physical and stability characteristics of enterically transmitted non-a, non-b hepatitis virus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102481 ◽

1988 ◽

Vol 46 ◽

pp. 80-81

Author(s):

Charles D. Humphrey ◽

E. H. Cook ◽

Karen A. McCaustland ◽

Daniel W. Bradley

Keyword(s):

Electron Microscopy ◽

Hepatitis A ◽

Hepatitis A Virus ◽

Solid Phase ◽

Etiologic Agent ◽

World Health ◽

Health Concern ◽

Morphological Identification ◽

Immune Electron Microscopy

Enterically transmitted non-A, non-B hepatitis (ET-NANBH) is a type of hepatitis which is increasingly becoming a significant world health concern. As with hepatitis A virus (HAV), spread is by the fecal-oral mode of transmission. Until recently, the etiologic agent had not been isolated and identified. We have succeeded in the isolation and preliminary characterization of this virus and demonstrating that this agent can cause hepatic disease and seroconversion in experimental primates. Our characterization of this virus was facilitated by immune (IEM) and solid phase immune electron microscopic (SPIEM) methodologies.Many immune electron microscopy methodologies have been used for morphological identification and characterization of viruses. We have previously reported a highly effective solid phase immune electron microscopy procedure which facilitated identification of hepatitis A virus (HAV) in crude cell culture extracts. More recently we have reported utilization of the method for identification of an etiologic agent responsible for (ET-NANBH).

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Identification of hepatitis a virus in cell cultures by solid phase immune electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142815 ◽

1986 ◽

Vol 44 ◽

pp. 238-239

Author(s):

C.D. Humphrey ◽

T.L. Cromeans ◽

E.H. Cook ◽

D.W. Bradley

Keyword(s):

Electron Microscopy ◽

Liquid Phase ◽

Cell Cultures ◽

Rapid Detection ◽

Hepatitis A ◽

Hepatitis A Virus ◽

Solid Phase ◽

Immune Electron Microscopy ◽

Detection And Identification

There is a variety of methods available for the rapid detection and identification of viruses by electron microscopy as described in several reviews. The predominant techniques are classified as direct electron microscopy (DEM), immune electron microscopy (IEM), liquid phase immune electron microscopy (LPIEM) and solid phase immune electron microscopy (SPIEM). Each technique has inherent strengths and weaknesses. However, in recent years, the most progress for identifying viruses has been realized by the utilization of SPIEM.

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Dynamic studies of silicide-mediated crystallization of amorphous silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131395 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1352-1353

Author(s):

C. Hayzelden ◽

J. L. Batstone

Keyword(s):

Ion Implantation ◽

Solid Phase ◽

Metallic Phase ◽

Single Crystal Substrate ◽

Free Electrons ◽

Melt Temperature ◽

Transmission Electron ◽

Crystal Substrate ◽

High Resolution Tem

Epitaxial reordering of amorphous Si(a-Si) on an underlying single-crystal substrate occurs well below the melt temperature by the process of solid phase epitaxial growth (SPEG). Growth of crystalline Si(c-Si) is known to be enhanced by the presence of small amounts of a metallic phase, presumably due to an interaction of the free electrons of the metal with the covalent Si bonds near the growing interface. Ion implantation of Ni was shown to lower the crystallization temperature of an a-Si thin film by approximately 200°C. Using in situ transmission electron microscopy (TEM), precipitates of NiSi2 formed within the a-Si film during annealing, were observed to migrate, leaving a trail of epitaxial c-Si. High resolution TEM revealed an epitaxial NiSi2/Si(l11) interface which was Type A. We discuss here the enhanced nucleation of c-Si and subsequent silicide-mediated SPEG of Ni-implanted a-Si.Thin films of a-Si, 950 Å thick, were deposited onto Si(100) wafers capped with 1000Å of a-SiO2. Ion implantation produced sharply peaked Ni concentrations of 4×l020 and 2×l021 ions cm−3, in the center of the films.

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TEM characterization of Au/Polysilicon interactions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176381 ◽

1990 ◽

Vol 48 (4) ◽

pp. 650-651

Author(s):

N. David Theodore ◽

Leslie H. Allen ◽

C. Barry Carter ◽

James W. Mayer

Keyword(s):

Solid Phase ◽

Single Crystal Silicon ◽

Chemical Vapor ◽

Electrical Contacts ◽

Silicon Substrates ◽

Crystal Silicon ◽

Transmission Electron ◽

Polysilicon Films ◽

The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

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