Optimized MALDI-TOF MS Strategy for Characterizing Polymers.
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ABSTRACT:
SUBMITTER: Wang Z
PROVIDER: S-EPMC8264446 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) is a powerful technique for analysis of various polymers, but it is still very difficult to characterize silicone oil due to its poor ionization efficiency. In this work, oligomeric hydroxyl silicone oils were successfully characterized by MALDI-TOF, by using pyridine-modified 2,5-dihydroxylbenzoic acid (DHB) as the matrix. Furthermore, the mixed crystal of DHB and hydroxyl silicone oil was analyzed by scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS), and the analytical results verified that modification with pyridine could remarkably improve the solubility of hydroxyl silicone oil in DHB, leading to the enhancement of its ionization efficiency in MALDI. The analysis of the MS spectra of a series of hydroxyl silicone oils indicated that they tended to be ionized by the attachment with Na+, and the average molecular weight and the degree of polymerization were measured for several oligomeric hydroxyl silicon oils.
| S-EPMC8650622 | biostudies-literature
Project description:ObjectiveTo evaluate the performance and validate the diagnostic value of a nucleotide matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) with the analysis process optimized in identification of mycobacterium species.MethodsThe optimized analysis process was used for mycobacterial identification in the nucleic MALDI-TOF-MS. 108 samples were used for assessing the performance of nucleic MALDI-TOF-MS, including 25 reference standards, 37 clinical isolates, 37 BALF, and 9 plasmids. The BALF of 38 patients suspected of pulmonary mycobacterial infection was collected for validation. Clinical etiological diagnosis was used as the gold standard to evaluate the diagnostic value of nucleotide MALDI-TOF-MS.ResultsThe sensitivity, specificity, and accuracy of the nucleotide MALDI-TOF-MS in mycobacterial identification were 96.91%, 100% and 97.22%, respectively, and the limit of detection for mycobacterium tuberculosis (MTB) was 50 bacteria/mL. Among 38 patients suspected of pulmonary mycobacterial infection, 33 were diagnosed with pulmonary tuberculosis infection, and 5 with non-mycobacterial infection. In clinical validation, the positive rates of MALDI-TOF-MS, Xpert MTB/RIF, culture and AFS in BALF of patients diagnosed with tuberculosis infection were 72.7%, 63.6%, 54.5% and 27.3%, respectively. The sensitivity/specificity of MALDI-TOF-MS, Xpert, culture and AFS in diagnosing MTB were 72.7%/100%, 63.6%/100%, 54.5%/100%, 27.3%/100%, with the areas under the curve of 0.864, 0.818, 0.773, and 0.636, respectively.ConclusionOptimized nucleotide MALDI-TOF-MS has satisfactory sensitivity, specificity and low LOD in the identification of mycobacteria, which may serve as a potential assay for mycobacterial identification.
| S-EPMC9755490 | biostudies-literature
Project description:Prenatal diagnosis aims either to provide the reassurance to the couples at risk of having an affected child by timely appropriate therapy or to give the parents a chance to decide the fate of the unborn babies with health problems. Invasive prenatal diagnosis (IPD) is accurate, however, carrying a risk of miscarriage. Non-invasive prenatal diagnosis (NIPD) has been developed based on the existing of fetal genetic materials in maternal circulation; however, a minority fetal DNA in majority maternal background DNA hinders the detections of fetal traits. Different protocols and assays, such as homogenous MassEXTEND (hME), single allele base extension reaction (SABER), precise measuring copy number variation of each allele, and quantitative methylation and expression analysis using the high-throughput sensitive matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), allow NIPD for single gene disorders, fetal blood group genotyping and fetal aneuploidies as well as the development of fetal gender-independent biomarkers in maternal circulation for management of pathological pregnancies. In this review, we summarise the use of MALDI-TOF MS in prenatal genomics.
| S-EPMC2941831 | biostudies-literature
Project description:MALDI-TOF mass spectrometry (MS) on whole cells enables the detection of different cell types and cell activation. Here, we wondered whether this approach would be useful to investigate the host response in sepsis.Peripheral blood mononuclear cells (PBMCs) from patients with severe sepsis and healthy donors were analyzed with MALDI-TOF MS. PBMCs from healthy donors were also stimulated with lipopolysaccharide, peptidoglycan, CpG oligonucleotides, polyinosinic polycytidylic acid, and with heat-inactivated bacteria. Averaged spectra of PBMCs stimulated in vitro by different agonists were generated from the database using the Biotyper software and matching scores between each spectrum from patients and averaged spectra from the database were calculated.We show that the MALDI-TOF MS signature of PBMCs from septic patients was specific, compared with healthy controls. As the fingerprints observed in patients may be related to PBMC activation, PBMCs from healthy controls were stimulated with cytokines, soluble Pathogen-Associated Molecular Patterns (PAMPs) and heat-killed bacteria, and we created a database of reference spectra. The MALDI-TOF MS profiles of PBMCs from septic patients were then compared with the database. No differences were found between patients with documented infection (n?=?6) and those without bacteriological documentation (n?=?6). The spectra of PBMCs from septic patients matched with those of interferon-?- and interleukin-10-stimulated PBMCs, confirming that sepsis is characterized by both inflammatory and immunoregulatory features. Interestingly, the spectra of PBMCs from septic patients without documented infection matched with the reference spectrum of PBMCs stimulated by CpG oligonucleotides, suggesting a bacterial etiology in these patients.Despite the limits of this preliminary study, these results indicate that the monitoring of functional status of PBMCs in peripheral blood by whole cell MALDI-TOF MS could provide unique opportunities to assess disease progression or resolution in clinical settings.
| S-EPMC6069833 | biostudies-other
Project description:A simple and fast method of lipid analysis of isolated intact mitochondria by means of MALDI-TOF mass spectrometry is described. Mitochondria isolated from bovine heart and yeast have been employed to set up and validate the new method of lipid analysis. The mitochondrial suspension is directly applied over the target and, after drying, covered by a thin layer of the 9-aminoacridine matrix solution. The lipid profiles acquired with this procedure contain all peaks previously obtained by analyzing the lipid extracts of isolated mitochondria by TLC and/or mass spectrometry. The novel procedure allows the quick, simple, precise, and accurate analysis of membrane lipids, utilizing only a tiny amount of isolated organelle; it has also been tested with intact membranes of the bacterium Paracoccus denitrificans for its evolutionary link to present-day mitochondria. The method is of general validity for the lipid analysis of other cell fractions and isolated organelles.
| S-EPMC3371254 | biostudies-literature
Project description:Analytical techniques currently available for the characterization of mixtures of microorganisms are generally based on next-generation sequencing. Motivated to develop practical and less-expensive methods for characterizing such mixtures, we propose, as an alternative or complement, the use of matrix-assisted laser-desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS), which is capable of high-resolution discrimination between species and even between biotypes within species. Potential approaches employing this technique for such characterization are discussed along with impediments to their successful employment. As a consequence, our rationale has been to capitalize on the powerful algorithms currently available for spectral comparison. Following this rationale, the first priority is to ensure the generation of MALDI-TOF MS spectra from mixtures of microorganisms that contain manageable peak complexities and that can be handled by the existing spectral comparison algorithms, preferably with the option to archive and re-run sample preparations and to pipette replicates of these onto MALDI-TOF MS sample plates. The second priority is to ensure that database entry is comparably facile to sample preparation so that large databases of known microorganism mixture MALDI-TOF MS spectra could be readily prepared for comparison with the spectra of unknown mixtures. In this article, we address the above priorities and generate illustrative MALDI-TOF MS spectra to demonstrate the utility of this approach. In addition, we investigate methods aimed at chemically modulating the peak complexity of the obtained MALDI-TOF MS spectra.
| S-EPMC7200911 | biostudies-literature
Project description:Truffles are edible mushrooms with similar morphological characteristics, that make it difficult to distinguish between highly prized truffles (such as the Périgord black T. melanosporum) and inexpensive truffles (such as the Asian Black T. indicum). These biological and economic features have led to several misidentifications and/or fraudulent profit in the truffle markets. In this paper, we investigate Matrix-assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) biotyping to identify 34 commercial fresh truffles from Europe and Asia. The MALDI-TOF MS clustering rapidly distinguished seven Tuber species identified by ITS phylogenetic analysis. The tasty T. melanosporum was clearly differentiated from the Chinese and less expensive truffles. These cheaper mushrooms were marketed as T. indicum but corresponded to a mix of three species. In total, the method confirmed misidentifications in 26% of commercial specimens. Several unknown blind-coded truffles were rapidly identified, with scores >= 2, using the Bruker Biotyper algorithm against MS databases. This study demonstrates that MALDI-TOF MS is a reliable, rapid and cheaper new tool compared with molecular methods for the identification of truffle species and could be used to control frauds in the truffle markets. It could also be useful for the certification of truffle-inoculated seedlings and/or diversity in forest ecosystems.
| S-EPMC6881316 | biostudies-literature
Project description:BackgroundIn the last decade, an innovative approach has emerged for arthropod identification based on matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Increasing interest in applying the original technique for arthropod identification has led to the development of a variety of procedures for sample preparation and selection of body parts, among others. However, the absence of a consensual strategy hampers direct inter-study comparisons. Moreover, these different procedures are confusing to new users. Establishing optimized procedures and standardized protocols for mosquito identification by MALDI-TOF MS is therefore a necessity, and would notably enable the sharing of reference MS databases. Here, we assess the optimal conditions for mosquito identification using MALDI-TOF MS profiling.MethodsThree homogenization methods, two of which were manual and one automatic, were used on three distinct body parts (legs, thorax, head) of two mosquito laboratory strains, Anopheles coluzzii and Aedes aegypti, and the results evaluated. The reproducibility of MS profiles, identification rate with relevant scores and the suitability of procedures for high-throughput analyses were the main criteria for establishing optimized guidelines. Additionally, the consequences of blood-feeding and geographical origin were evaluated using both laboratory strains and field-collected mosquitoes.ResultsRelevant score values for mosquito identification were obtained for all the three body parts assayed using MALDI-TOF MS profiling; however, the thorax and legs were the most suitable specimens, independently of homogenization method or species. Although the manual homogenization methods were associated with a high rate of identification on the three body parts, this homogenization mode is not adaptable to the processing of a large number of samples. Therefore, the automatic homogenization procedure was selected as the reference homogenization method. Blood-feeding status did not hamper the identification of mosquito species, despite the presence of MS peaks from original blood in the MS profiles of the three body parts tested from both species. Finally, a significant improvement in identification scores was obtained for field-collected specimens when MS spectra of species from the same geographical area were added to the database.ConclusionThe results of the current study establish guidelines for the selection of mosquito anatomic parts and modality of sample preparation (e.g. homogenization) for future specimen identification by MALDI-TOF MS profiling. These standardized operational protocols could be used as references for creating an international MS database.
| S-EPMC9248115 | biostudies-literature
Project description:We describe a new method for encoded synthesis, efficient on-resin screening, and rapid unambiguous sequencing of combinatorial peptide libraries. An improved binary tag system for encoding peptide libraries during synthesis was designed to facilitate unequivocal assignment of isobaric residues by MALDI-TOF MS analysis. The improved method for encoded library synthesis was combined with a new versatile on-resin screening strategy that permitted multiple stages and types of screening to be employed successively on one library under mild conditions. The new method facilitated a combinatorial study of transglutaminase (TGase) enzyme substrate peptides, revealing new details of the effect of amino acid composition on TGase substrates. The approach was first demonstrated for an encoded library (130,321 compounds) of lysine pentapeptide substrates of TGase, synthesized using the "split-mix" method. The library was reacted on-resin with TGase enzyme and a soluble desthiobiotin labeled glutamine substrate. Initial screening was performed by adsorbing streptavidin-coated magnetic microparticles onto library beads, followed by magnetic separation. The differential binding affinities of desthiobiotin and biotin for streptavidin were exploited to release the magnetic microparticles and regenerate the desthiobiotin-labeled resin beads for further screening by flow-cytometry-based automated bead sorting, resulting in 345 beads that were sequenced by MALDI-TOF MS analysis. A second library consisted of encoded glutamine hexapeptide substrates, which was reacted on-resin with TGase enzyme and a soluble desthiobiotin-labeled cadaverine. Two-stage screening identified 267 glutamine peptides as TGase-reactive, of which 21 were further analyzed by solution-phase enzyme kinetics. Kinetic results indicated that the peptide PQQQYV from the library has a 68-fold greater substrate specificity than the best known glutamine substrate QQIV. The new encoding and screening strategies described here are expected to be broadly applicable to synthesis and screening of combinatorial peptide libraries in the future.
| S-EPMC2586901 | biostudies-other
Project description:Gluten protein composition determines the rheological characteristics of wheat dough and is influenced by variable alleles with distinct effects on processing properties. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), we determined the high-molecular weight glutenin subunit (HMW-GS) composition of 665 wheat genotypes employed in breeding programs in South Korea. We identified 22 HMW-GS alleles, including 3 corresponding to the Glu-A1 locus, 14 to Glu-B1, and 5 to Glu-D1. The Glu-1 quality score, which is an important criterion for high-quality wheat development, was found to be 10 for 105/665 (15.79%) of the studied genotypes, and included the following combinations of HMW-GS: 2*, 7 + 8, 5 + 10; 2*, 17 + 18, 5 + 10; 1, 7 + 8, 5 + 10; and 1, 17 + 18, 5 + 10. To select wheat lines with the 1Bx7 overexpression (1Bx7OE) subunit, which is known to have a positive effect on wheat quality, we used a combination of MALDI-TOF-MS and published genotyping markers and identified 6 lines carrying 1Bx7OE out of the 217 showing a molecular weight of 83,400 Da, consistent with 1Bx7G2 and 1Bx7OE. This study demonstrates that the MALDI-TOF-MS method is fast, accurate, reliable, and effective in analyzing large numbers of wheat germplasms or breeding lines in a high-throughput manner.Supplementary informationThe online version contains supplementary material available at 10.1007/s13205-020-02637-z.
| S-EPMC7829314 | biostudies-literature