scholarly journals Disinfection chemicals mode of action on the bacterial spore structure and their Raman spectra

2020 ◽  
Author(s):  
Dmitry Malyshev ◽  
Tobias Dahlberg ◽  
Krister Wiklund ◽  
Per Ola Andersson ◽  
Sara Henriksson ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Sodium Hypochlorite ◽  
Chlorine Dioxide ◽  
Peracetic Acid ◽  
Structural Changes ◽  
Detection Methods ◽  
Laser Tweezers ◽  
Rapid Diagnostics ◽  
Spore Forming Bacteria

AbstractContamination of toxic spore-forming bacteria is problematic since spores can survive a plethora of disinfection chemicals. It is also problematic to rapidly detect if the disinfection chemical was active, leaving spores dead. Robust decontamination strategies, as well as reliable detection methods to identify dead from viable spores, are thus critical. Vibrational detection methods such as Raman spectroscopy has been suggested for rapid diagnostics and differentiation of live and dead spores. We investigate in this work, using laser tweezers Raman spectroscopy, the changes in Raman spectra of Bacillus thuringiensis spores treated with sporicidal agents such as chlorine dioxide, peracetic acid, and sodium hypochlorite. We also imaged treated spores using SEM and TEM to verify if any changes to the spore structure can be correlated to the Raman spectra. We found that chlorine dioxide did not change the Raman spectrum or the spore structure; peracetic acid shows a time-dependent decrease in the characteristic DNA/DPA peaks and ∼20 % of the spores were degraded and collapsed; spores treated with sodium hypochlorite show an abrupt drop in DNA and DPA peaks within 20 minutes all though the spore structure was overall intact, however, the exosporium layer was reduced. Structural changes appeared over several minutes, compared to the inactivation time of the spores, which is less than a minute. We conclude that vibrational spectroscopy provides powerful means to detect changes in spores but it might be problematic to identify if spores are live or dead after a decontamination procedure.

scholarly journals Formation of irregular rings in silica aerogel structure during the sintering process

2003 ◽  
Vol 35 (2) ◽  
pp. 67-73
Author(s):  
Ivana Hinic ◽  
Goran Stanisic ◽  
Zoran Popovic
Keyword(s):  
Raman Spectroscopy ◽  
Bulk Density ◽  
Raman Spectra ◽  
Silica Aerogel ◽  
Structural Changes ◽  
Low Density ◽  
Sintering Process ◽  
Time Intervals ◽  
Defect Modes

Samples of low-density, highly disordered silica aerogel with initial bulk density of 0.16 g/cm3, were sintered isothermally in different time intervals at 1000?C. Structural changes during the sintering process have been investigated by Raman spectroscopy. Defect modes of irregular three and four membered rings were observed in the Raman spectra of sintered samples.

Interspecies Interactions in Dual-Species Biofilms Formed by Psychrotrophic Bacteria and the Tolerance of Sessile Communities to Disinfectants

2020 ◽  
Vol 83 (6) ◽  
pp. 951-958 ◽  
Author(s):  
LEI YUAN ◽  
NI WANG ◽  
FAIZAN A. SADIQ ◽  
GUOQING HE
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hypochlorite ◽  
Peracetic Acid ◽  
Laser Scanning ◽  
Structural Changes ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Interspecies Interactions ◽  
Mixed Species ◽  
Psychrotrophic Bacteria

ABSTRACT Biofilms on the surface of food processing equipment act as potential reservoirs of microbial contamination. Bacterial interactions are believed to play key roles in both biofilm formation and antimicrobial tolerance. In this study, Aeromonas hydrophila, Chryseobacterium oncorhynchi, and Pseudomonas libanensis, which were previously isolated from Chinese raw milk samples, were selected to establish two dual-species biofilm models (P. libanensis plus A. hydrophila and P. libanensis plus C. oncorhynchi) on stainless steel at 7°C. Subsequently, three disinfectants, hydrogen peroxide (100 ppm), peracetic acid (100 ppm), and sodium hypochlorite (100 ppm), were used to treat the developed sessile communities for 10 min. Structural changes after exposure to disinfectants were analyzed with confocal laser scanning microscopy. The cell numbers of both A. hydrophila and C. oncorhynchi recovered from surfaces increased when grown as dual species biofilms with P. libanensis. Dual-species biofilms were more tolerant of disinfectants than were each single-species biofilm. Peracetic acid was the most effective disinfectant for removing biofilms, followed by hydrogen peroxide and sodium hypochlorite. The results expand the knowledge of mixed-species biofilms formed by psychrotrophic bacteria and will be helpful for developing effective strategies to eliminate bacterial mixed-species biofilms. HIGHLIGHTS

Laser Tweezers Raman Spectroscopy Detects Differences between Normal Human Lymphocytes, Activated Lymphocytes and Leukemia.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4530-4530
Author(s):  
Douglas Scott Taylor ◽  
James W. Chan ◽  
Theodore Zwerdling ◽  
Stephen M. Lane ◽  
Joeseph Tuscano ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
B Cells ◽  
Raman Spectra ◽  
Single Cells ◽  
Human Lymphocytes ◽  
Leukemia Cells ◽  
Laser Tweezers ◽  
Human Leukemia ◽  
T And B Cells ◽  
Normal Human

Abstract Raman spectroscopy is a laser-based analytical technique that enables chemical characterization of molecules in a sample. It is based on the inelastic scattering of photons by molecular bond vibrations. A Raman spectrum obtained from single cells is an intrinsic molecular fingerprint of the sample, revealing detailed information about DNA, RNA, protein, lipid, and carbohydrate content as well as macromolecular conformations. This technique is rapid, non-invasive and non-destructive. We have demonstrated that single-cell laser tweezers Raman spectroscopy (LTRS) reliably discriminates between normal human T- and B-lymphocytes and their transformed, Jurkat-T and Raji-B, counterparts. Herein the same technique is used to discern normal human T- and B-cells from T- and preB-leukemia cells. Also, demonstrated are Raman spectra changes that result from the activation of normal T-cells with a combination of TPA and ionomycin, and normal B-cells by cross linkage of surface immunoglobulin. T- and B-cells were isolated from healthy volunteers. T- and preB-leukemia cells were isolated from patient samples. Spectra are both compared directly and analyzed by principal component analysis. Significant Raman spectra differences in characteristic DNA and protein signals discriminate between normal cells and their leukemia counterparts. Human leukemia cells were indistinguishable from Jurkat-T and Raji-B cells. Changes in spectra that result from cell activation and proliferation only partially account for the spectra changes of leukemia cells. These data demonstrate the utility of LTRS to discern normal lymphocytes from both transformed cells and leukemia cells.

scholarly journals Exploring the potential synergistic effects of chemical disinfectants and UV on the inactivation of free-living bacteria and treatment of biofilms in a pilot-scale system

2011 ◽  
Vol 64 (6) ◽  
pp. 1247-1253 ◽  
Author(s):  
E. Vankerckhoven ◽  
B. Verbessem ◽  
S. Crauwels ◽  
P. Declerck ◽  
K. Muylaert ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hypochlorite ◽  
Chlorine Dioxide ◽  
Peracetic Acid ◽  
Synergistic Effects ◽  
Pilot Scale ◽  
Bacterial Suspension ◽  
Additive Effects ◽  
Free Living ◽  
Living Bacteria

The main objective of this study is to explore possible synergistic or additive effects of combinations of chemical disinfectants (sodium hypochlorite, peracetic acid, hydrogen peroxide, chlorine dioxide) and UV in their efficacy in inactivating free-living bacteria and removing biofilms. In contrast to most studies, this study examines disinfection of municipal water in a pilot-scale system using a mixed bacterial suspension, which enables a better simulation of the conditions encountered in actual industrial environments. It was shown that the combination of either hypochlorite, hydrogen peroxide, peracetic acid, or chlorine dioxide with UV yielded additive effects on the inactivation of free-living bacteria. Actual synergy was observed for the combination of UV and 5 ppm hydrogen peroxide. Regarding biofilm treatment, additive effects were observed using the combination of hydrogen peroxide and UV. The promising results obtained in this study indicate that the combination of UV and chemical disinfectants can considerably reduce the amount of chemicals required for the effective disinfection and treatment of biofilms.

Nanoindentation-Induced Phase Transformation in Silicon Thin Films

2013 ◽  
Vol 586 ◽  
pp. 112-115 ◽  
Author(s):  
Radim Ctvrtlik ◽  
Jan Tomastik ◽  
Vaclav Ranc
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
High Pressure ◽  
Phase Transformation ◽  
Raman Spectra ◽  
Structural Changes ◽  
Berkovich Indenter ◽  
Silicon Thin Films ◽  
Free Silicon ◽  
Amorphous Si

Nanoindentation-induced phase transformation of amorphous, annealed amorphous and microcrystalline hydrogen-free silicon thin films were studied. Series of nanoindentation experiments were performed with a sharp Berkovich indenter at various unloading rates. The structural changes in indentation deformed regions were examined using Raman spectroscopy. Analyses of indentation curves and Raman spectra suggest that high pressure phases appear more easily in annealed amorphous Si thin films than in microcrystalline ones.

scholarly journals Discrimination between ricin and sulphur mustard toxicity in vitro using Raman spectroscopy

2004 ◽  
Vol 1 (1) ◽  
pp. 79-90 ◽  
Author(s):  
Ioan Notingher ◽  
Chris Green ◽  
Chris Dyer ◽  
Elaine Perkins ◽  
Neil Hopkins ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Structural Changes ◽  
High Accuracy ◽  
Biochemical Properties ◽  
Prediction Errors ◽  
Toxic Agent ◽  
Linear Discriminant ◽  
Sulphur Mustard

A Raman spectroscopy cell-based biosensor has been proposed for rapid detection of toxic agents, identification of the type of toxin and prediction of the concentration used. This technology allows the monitoring of the biochemical properties of living cells over long periods of time by measuring the Raman spectra of the cells non-invasively, rapidly and without use of labels (Notingher et al. 2004 doi:10.1016/j.bios.2004.04.008). Here we show that this technology can be used to distinguish between changes induced in A549 lung cells by the toxin ricin and the chemical warfare agent sulphur mustard. A multivariate model based on principal component analysis (PCA) and linear discriminant analysis (LDA) was used for the analysis of the Raman spectra of the cells. The leave-one-out cross-validation of the PCA-LDA model showed that the damaged cells can be detected with high sensitivity (98.9%) and high specificity (87.7%). High accuracy in identifying the toxic agent was also found: 88.6% for sulphur mustard and 71.4% for ricin. The prediction errors were observed mostly for the ricin treated cells and the cells exposed to the lower concentration of sulphur mustard, as they induced similar biochemical changes, as indicated by cytotoxicity assays. The concentrations of sulphur mustard used were also identified with high accuracy: 93% for 200 μM and 500 μM, and 100% for 1000 μM. Thus, biological Raman microspectroscopy and PCA-LDA analysis not only distinguishes between viable and damaged cells, but can also discriminate between toxic challenges based on the cellular biochemical and structural changes induced by these agents and the eventual mode of cell death.

Laser Tweezers Raman Spectroscopy (LTRS) to Detect Effects of Chlorine Dioxide on IndividualNosema bombycisSpores

2019 ◽  
Vol 73 (7) ◽  
pp. 774-780
Author(s):  
Yu Zhang ◽  
Zhenbin Miao ◽  
Xuhua Huang ◽  
Xiaochun Wang ◽  
Junxian Liu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Real Time ◽  
Chlorine Dioxide ◽  
Single Cell Analysis ◽  
Protein Structures ◽  
Protein Secondary Structure ◽  
Spore Wall ◽  
Time Range ◽  
Laser Tweezers ◽  
Α Helix

The microsporidium Nosema bombycis (Nb) causes pebrine, a fatal disease in sericulture. Nb is effectively killed by chlorine dioxide (ClO2); however, the precise killing mechanism remains unclear. We used laser tweezers Raman spectroscopy (LTRS) to monitor the action of ClO2on individual Nb spores in real time. Raman peaks of ClO2appeared in Nb spores, corresponding to decreased peaks of trehalose that gradually disappeared. A peak (1658 cm–1) corresponding to the protein α-helix significantly weakened while that (1668 cm–1) corresponding to irregular protein structures was enhanced; their intensities were negatively correlated in a certain time range and dependent on ClO2concentration. The intensities of peaks at 782 cm–1(nucleic acids) and 1004 cm–1(phenylalanine of protein) did not change evidently even under extremely high ClO2concentrations. Thus, ClO2rapidly permeates the Nb spore wall, changing the protein secondary structure to lose biological function and destroy permeability, causing trehalose to leak out. These effects are ClO2concentration-dependent, but no other obvious changes to biomacromolecules were detected. Single-cell analysis using LTRS is an effective method to monitor the action of chemical sporicides on microbes in real time, providing insight into the heterogeneity of cell stress resistance.

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