Monitoring the size and the stability of zinc oxide quantum dots in biological media: a soft ionization mass spectrometry technique (MALDI-TOF-MS)

2015 ◽  
Vol 1793 ◽  
pp. 7-12
Author(s):  
Jean-Jacques Gaumet ◽  
Gabriel Gaiffe ◽  
Clément Dezanet ◽  
Stéphane Dalmasso ◽  
Pierre Magri ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Quantum Dots ◽  
Sol Gel ◽  
Ionization Mass ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Physico Chemical ◽  
The Stability ◽  
Zno Qds ◽  
Tof Ms

ABSTRACTWe present herein a joint physical/physico-chemical study and, more specifically, the first application of Matrix Assisted Laser Desorption Ionization coupled with Time of Flight Mass Spectrometry (MALDI-TOF-MS) to analyze small-sized ZnO quantum dots (QDs) (2.8-3.1 nm diameter range) synthesized by sol-gel chemistry and stabilized through an aminosilane coating. A careful investigation of the stability of ZnO QDs was initiated once these dots were dispersed in different media (water, biological buffer) for a period up to 3 weeks. Positive ion mode mass spectra MALDI-TOF-MS combined with optical spectrometry was used to monitor the stability of ZnO QDs when aging. Such a unique combination of MALDI-TOF-MS and physico-chemical techniques is likely to bring new insights into the structure analysis, the stability and consequently the potential toxicity of QDs.

scholarly journals Effect of Culture Conditions on Microorganism Identification by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

2005 ◽  
Vol 71 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Nancy Valentine ◽  
Sharon Wunschel ◽  
David Wunschel ◽  
Catherine Petersen ◽  
Karen Wahl
Keyword(s):  
Mass Spectrometry ◽  
Laser Desorption ◽  
Ionization Mass ◽  
Laser Desorption Ionization ◽  
Maldi Tof Ms ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Tof Ms ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACT Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has been used to identify bacteria based upon protein signatures. This research shows that while some different proteins are produced by vegetative bacteria when they are cultured in different growth media, positive identification with MALDI-TOF MS is still possible with the protocol established at the Pacific Northwest National Laboratory (K. H. Jarman, S. T. Cebula, A. J. Saenz, C. E. Petersen, N. B. Valentine, M. T. Kingsley, and K. L. Wahl, Anal. Chem. 72:1217-1223, 2000). A core set of small proteins remain constant under at least four different culture media conditions and blood agar plates, including minimal medium M9, rich media, tryptic soy broth (TSB) or Luria-Bertani (LB) broth, and blood agar plates, such that analysis of the intact cells by matrix-assisted laser desorption/ionization mass spectrometry allows for consistent identification.

scholarly journals Using MALDI-TOF mass spectrometry to identify ticks collected on domestic and wild animals from the Democratic Republic of the Congo

2021 ◽  
Author(s):  
Steve Ngoy ◽  
Adama Zan Diarra ◽  
Anne Laudisoit ◽  
Guy-Crispin Gembu ◽  
Erik Verheyen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Democratic Republic ◽  
Morphological Identification ◽  
Ionization Mass ◽  
Wild Animals ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Republic Of The Congo ◽  
Reference Specimens ◽  
Tof Ms

AbstractMatrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) has recently emerged as an alternative to morphological and molecular tools to identify tick species. In this study, we set out to evaluate and confirm the ability of MALDI-TOF MS to identify different species of ticks collected in the Democratic Republic of the Congo and preserved in 70% ethanol. A total of 575 ticks, of which 530 were collected from domestic pigs and 45 from wild animals, were subjected to MALDI-TOF MS analysis to evaluate the intraspecies reproducibility and interspecies specificity of MS profiles obtained from the different species. Morphologically, the ticks belonged to seven different species, namely Rhipicephalus complanatus, Rhipicephalus congolensis, Haemaphysalis muhsamae, Ixodes cumulatimpunctatus, Amblyomma exornatum, Amblyomma compressum and an unidentified Rhipicephalus sp. A total of 535/575 (93%) of the spectra obtained were of good enough quality to be used for our analyses. Our home-made MALDI-TOF MS arthropod database was upgraded with spectra obtained from between one and five randomly selected specimens per species. For these reference specimens, molecular identification of the ticks was also made using 16S, 12S rDNA genes and the Cox1 mtDNA gene sequencing. The remaining good quality spectra were then queried against the upgraded MALDI-TOF MS database, showing that 100% were in agreement with the morphological identification, with logarithmic score values (LSVs) between 1.813 and 2.51. The consistency between our morphological, molecular and MALDI-TOF MS identification confirms the capability and precision of MALDI-TOF MS for tick identification.

scholarly journals MALDI-TOF Mass Spectroscopy Applications in Clinical Microbiology

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Maryam Alizadeh ◽  
Leila Yousefi ◽  
Farzaneh Pakdel ◽  
Reza Ghotaslou ◽  
Mohammad Ahangarzadeh Rezaee ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Diagnostic Methods ◽  
Ionization Mass ◽  
Two Dimensional Gel Electrophoresis ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Comprehensive Information ◽  
Tof Ms

There is a range of proteomics methods to spot and analyze bacterial protein contents such as liquid chromatography-mass spectrometry (LC-MS), two-dimensional gel electrophoresis, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS), which give comprehensive information about the microorganisms that may be helpful within the diagnosis and coverings of infections. Microorganism identification by mass spectrometry is predicted on identifying a characteristic spectrum of every species so matched with an outsized database within the instrument. MALDI-TOF MS is one of the diagnostic methods, which is a straightforward, quick, and precise technique, and is employed in microbial diagnostic laboratories these days and may replace other diagnostic methods. This method identifies various microorganisms such as bacteria, fungi, parasites, and viruses, which supply comprehensive information. One of the MALDI-TOF MS’s crucial applications is bacteriology, which helps identify bacterial species, identify toxins, and study bacterial antibiotic resistance. By knowing these cases, we will act more effectively against bacterial infections.

scholarly journals Diagnostic accuracy of MALDI-TOF mass spectrometry for the direct identification of clinical pathogens from urine

Open Medicine ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 266-273
Author(s):  
Min Tang ◽  
Jia Yang ◽  
Ying Li ◽  
Luhua Zhang ◽  
Ying Peng ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Likelihood Ratio ◽  
Meta Analysis ◽  
Positive Likelihood Ratio ◽  
Negative Likelihood Ratio ◽  
Urine Samples ◽  
Direct Identification ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

AbstractMatrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) has become one of the most popular methods for the rapid and cost-effective detection of clinical pathogenic microorganisms. This study aimed to evaluate and compare the diagnostic performance of MALDI-TOF MS with that of conventional approaches for the direct identification of pathogens from urine samples. A systematic review was conducted based on a literature search of relevant databases. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the summary receiver operating characteristic (SROC) curve of the combined studies were estimated. Nine studies with a total of 3920 subjects were considered eligible and included in the meta-analysis. The pooled sensitivity was 0.85 (95% CI 0.79-0.90), and the pooled specificity was 0.93 (95% CI 0.82-0.97). The PLR and NLR were 11.51 (95% CI 4.53-29.26) and 0.16 (95% CI 0.11-0.24), respectively. The area under the SROC curve was 0.93 (95% CI 0.91-0.95). Sensitivity analysis showed that the results of this meta-analysis were stable. MALDI-TOF MS could directly identify microorganisms from urine samples with high sensitivity and specificity.

scholarly journals The Use of MALDI-TOF Mass Spectrometry to Analyze Commensal Oral Yeasts in Nursing Home Residents

2021 ◽  
Vol 9 (1) ◽  
pp. 142
Author(s):  
Jang-Jih Lu ◽  
Hsiu-Jung Lo ◽  
Chih-Hua Lee ◽  
Mei-Jun Chen ◽  
Chih-Chao Lin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nursing Home ◽  
Dna Sequences ◽  
Nursing Home Residents ◽  
Practical Method ◽  
Elderly Subjects ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Oral Yeasts ◽  
Tof Ms

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method to identify microorganisms in clinical laboratories. This study isolates yeast-like microorganisms in the oral washes that are collected from non-bedridden nursing home residents, using CHROMagar Candida plates, and identifies them using Bruker MALDI-TOF MS. The ribosomal DNA sequences of the isolates are then examined. Three hundred and twenty yeast isolates are isolated from the oral washes. Candida species form the majority (78.1%), followed by Trichosporon/Cutaneotrichosporon species (8.8%). Bruker MALDI-TOF MS gives a high-level confidence, with a log(score) value of ≥1.8, and identifies 96.9% of the isolates. There are six inconclusive results (1.9%), and those sequences are verified as rare clinical species, including Candida ethanolica, Cutaneotrichosporon jirovecii, Exophiala dermatitidis, and Fereydounia khargensis. Almost all of the isolates have a regular color on the CHROMagar Candida plates. If the colonies are grouped by color on the plates, a specific dominant yeast species is present in each color group, except for purple or orange isolates. In conclusion, MALDI-TOF MS is verified as a fast, accurate and practical method to analyze oral yeasts in elderly subjects.

Microorganism idenitfication – stability and correctness of mass spectrometry method (MALDI TOF MS)

2021 ◽  
Vol 56 (4) ◽  
pp. 1-12
Author(s):  
Łukasz Hildebrant ◽  
Urszula Wendt
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Control System ◽  
High Stability ◽  
Spectrometry Method ◽  
Maldi Tof Ms ◽  
Mass Spectrometry Method ◽  
Maldi Tof ◽  
Reference Strains ◽  
Tof Ms

Introduction: MALDI TOF MS method is increasingly used in routine microbiological diagnostics to identify clinical strains. The result of the identification test is based on the measurement of the mass, charge and flight time of the protein ions. This makes it possible to monitor and supervise the method using a numerical score developed with statistical techniques. Aim: The study aimed to determine the stability and correctness of the mass spectrometry method. Materials and methods: To evaluate the characteristics of the method, microbial identification tests were performed using reference strains. All tests were performed as part of the MALDI TOF MS internal quality control system. Results: All reference strains (100%) were correctly identified to the species level, although the score values were not always within the reliability criteria of the results established by the producer. It was found that the mean values of the score were from 2.000 – 2.299 (49.2%) and 2.300 – 3.000 (50.0%). The coefficient of variation for control tests performed in the consecutive years ranged from 5.18 – 6.56%, which evidence of the high stability of the method. For individual species, reproducibility precision over the 8 years ranged from 2.89% (n = 13) for Enterococcus faecalis ATCC 51299 to 7.02% (n = 28) for Klebsiella pneumoniae ATCC 700603, which proves the high precision of measurements. Conclusions: The mass spectrometry method is characterized by very high stability and correctness. The intra-laboratory quality control system using reference strains is a useful tool for monitoring and supervising the method and laboratory personnel competency performing identification tests during routine microbiological work.

scholarly journals Detection of Structural and Conformational Changes in ALS-Causing Mutant Profilin1 With Hydrogen/Deuterium Exchange Mass Spectrometry and Bioinformatics Techniques

2021 ◽  
Author(s):  
Ahmad Shahir Sadr ◽  
zahra abdollahpour ◽  
Atousa Aliahmadi ◽  
Changiz Eslahchi ◽  
Mina Nekouei ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Amino Acid ◽  
Conformational Changes ◽  
Docking Simulation ◽  
Hydrogen Deuterium Exchange ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Hydrogen Deuterium ◽  
Tof Ms

Abstract The hydrogen/deuterium exchange (HDX) is a reliable method to survey the dynamic behavior of proteins and epitope mapping. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) is a quantifying tool to assay for HDX in the protein of interest. We combined HDX-MALDI-TOF MS and molecular docking/MD simulation to identify accessible amino acids and analyze their contribution in the structural changes of profilin1 (PFN1). The molecular docking/MD simulations are computational tools for enabling the analysis of the type of amino acids that may be involved via HDX identified under the lowest binding energy condition. Glycine to Valine amino acid (G117V) substitution mutation is linked to amyotrophic lateral sclerosis (ALS). This mutation is found to be in the actin-binding site of PFN1 and prevents the dimerization/polymerization of actin and invokes a pathologic toxicity that leads to ALS. In this study, we sought to understand the PFN1 protein dynamic behavior using purified wild type and mutant PFN1 proteins. The data obtained from HDX-MALDI-TOF MS for PFN1WT and PFN1G117V at various time intervals, from seconds to hours, revealed multiple peaks corresponding to molecular weights from monomers to multimers. PFN1/Benzaldehyde complexes identified 20 accessible amino acids to HDX that participate in the docking simulation in the surface of WT and mutant PFN1. Consistent results from HDX-MALDI-TOF MS and docking simulation predict candidate amino acid(s) involved in the dimerization/polymerization of PFNG117V. This information may shed critical light on the structural and conformational changes with details of amino acid epitopes for mutant PFN1s’ dimerization, oligomerization, and aggregation.

scholarly journals Use of the proteomic tool MALDI-TOF MS in termite identification

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Bouthaina Hasnaoui ◽  
Adama Zan Diarra ◽  
Jean-Michel Berenger ◽  
Hacène Medkour ◽  
Ahmed Benakhla ◽  
...  
Keyword(s):  
Ionization Mass ◽  
Laser Desorption Ionization ◽  
Termite Species ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Promising Tool ◽  
Macrotermes Bellicosus ◽  
Amitermes Evuncifer ◽  
Macrotermes Herus ◽  
Tof Ms

AbstractMatrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) has proved effective for the identification of many arthropods. A total of 432 termite specimens were collected in Mali, Cote d’Ivoire, Togo, Senegal, Switzerland and France. Morphologically, 22 species were identified, including Ancistrotermes cavithorax, Amitermes evuncifer, Cryptotermes brevis, Cubitermes orthognathus, Kalotermes flavicollis, Macrotermes bellicosus, Macrotermes herus, Macrotermes ivorensis, Macrotermes subhyalinus, Microcerotermes parvus, Microtermes sp., Odontotermes latericius, Procubitermes sjostedti, Promirotermes holmgreni, Reticulitermes grassei, Reticulitermes lucifugus, Reticulitermes santonensis, Trinervitermes geminatus, Trinervitermes occidentalis, Trinervitermes togoensis, Trinervitermes sp., Trinervitermes trinervoides and Trinervitermes trinervius. Analysis of MALDI-TOF MS spectra profiles from termites revealed that all were of high quality, with intra-species reproducibility and inter-species specificity. Blind testing of the spectra of 389 termites against our updated database with the spectra of 43 specimens of different termite species revealed that all were correctly identified with log score values (LSVs) ranging from 1.65 to 2.851, mean 2.290 ± 0.225, median 2.299, and 98.4% (383) had LSVs > 1.8. This study is the first on the use of MALDI-TOF for termite identification and shows its importance as a tool for arthropod taxonomy and reinforces the idea that MALDI-TOF MS is a promising tool in the field of entomology.

scholarly journals Outbreak of botulism type A in dairy cows detected by MALDI-TOF mass spectrometry

2020 ◽  
Vol 32 (5) ◽  
pp. 722-726
Author(s):  
Elisha A. Frye ◽  
Christina Egan ◽  
Michael J. Perry ◽  
Esther E. Crouch ◽  
Kyle E. Burbank ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
New York ◽  
New York State ◽  
Clinical Signs ◽  
Type A ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Botulinum Type ◽  
Type C ◽  
Tof Ms

Twenty-eight lactating dairy cattle in New York State were exposed to botulism toxin; 12 died and 16 recovered but never returned to full productivity. Pieces of a raccoon carcass were found in the total mixed ration on the first day of the outbreak. Clinical signs included anorexia, decreased milk production, decreased tongue tone, profound weakness, and recumbency. Clostridium botulinum type A (BoNT/A) was detected in rumen contents from 2 deceased cows via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In addition, C. botulinum type C was cultured from the liver of a third cow, and C. botulinum neurotoxin-producing type C gene ( bont/C) was detected via real-time PCR. On postmortem examination, 4 cows had findings suggestive of toxic myopathy, but the cause and significance of these lesions is unknown given that botulism is typically not associated with gross or histologic lesions. This outbreak of BoNT/A in cattle in North America was diagnosed via MALDI-TOF MS, a rapid and sensitive modality for detection of botulinum preformed neurotoxin.

scholarly journals The clinical relevance of pathogen Aerococcus urinae identification by MALDI-TOF mass spectrometry: a case of sepsis in 86-year-old Caucasian male

2020 ◽  
Vol 35 (2) ◽  
Author(s):  
Jari Intra ◽  
Cecilia Sarto ◽  
Giuseppe Serra ◽  
Paolo Brambilla
Keyword(s):  
Mass Spectrometry ◽  
Urinary Tract ◽  
Previous History ◽  
Blood Stream ◽  
Maldi Tof Ms ◽  
Maldi Tof Mass Spectrometry ◽  
Maldi Tof ◽  
Microbiological Methods ◽  
Aerococcus Urinae ◽  
Tof Ms

The infrequency of urinary tract and blood stream infections caused by Aerococcus urinae is most probably due to the difficulties in the identification of this bacterium using standard microbiological methods. With the introduction of more sensitive and accurate techniques in clinical microbiology, such as genetic approaches and Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry (MS), the incidence of infections due to A. urinae increased. Herein, we described a case of urinary tract and bloodstream infection caused by A. urinae, which occurred in an 86-year-old Caucasian man with a previous history of prostate cancer. The identification of A. urinae was performed by MALDI-TOF MS, since this microorganism cannot be identified by biochemical reactions. In this report, we highlight the need to consider MALDI-TOF MS as technique of choice for A. urinae identification in the presence of subjects with predisposing factors, such as old age, male gender, and genitourinary tract pathologies.

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