Добірка наукової літератури з теми "Saldi-Ms"

Surface-assisted laser desorption/ionization (SALDI) coupled with mass spectrometry (MS) is frequently used to analyse small organics owing to its clean background. Inorganic materials can be used as energy absorbers and the transfer medium to facilitate the desorption/ionization of analytes; thus, they are used as SALDI-assisting materials. Many studies have demonstrated the usefulness of SALDI-MS in quantitative analysis of small organics. However, some characteristics occurring in SALDI-MS require certain attention to ensure the reliability of the quantitative analysis results. The appearance of a coffee-ring effect in SALDI sample preparation is the primary factor that can affect quantitative SALDI-MS analysis results. However, to the best of our knowledge, there are no reports relating to quantitative SALDI-MS analysis that discuss or consider this effect. In this study, the coffee-ring effect is discussed using nanoparticles and nanostructured substrates as SALDI-assisting materials to show how this effect influences SALDI-MS analysis results. Potential solutions for overcoming the existing problems are also suggested. This article is part of the themed issue ‘Quantitative mass spectrometry’.

This study aimed to detect and quantify mycotoxins on building materials using innovative laser mass spectroscopy methods—silver-109/silver/gold nanoparticle-enhanced target surface-assisted laser desorption/ionisation mass spectrometry (109AgNPs, AgNPs and AuNPs SALDI). Results from SALDI-type methods were also compared with commonly used matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Standards of seven moulds mycotoxin in a final concentration of 100 µg/mL for patulin, citrinin, 3-nitropropionic acid, alternariol and 20 µg/mL for sterigmatocystin, cyclopiazonic acid, roquefortine C in the mixture were tested in pure solutions and after extraction from the plasterboards. Among the studied SALDI-type method, the lowest detection limits and the highest signal intensity of the mycotoxins tested were obtained with the use of 109AgNPs SALDI MS. The 109AgNPs method may be considered as an alternative to the currently most frequently used method MALDI MS and also liquid chromatography tandem mass spectrometry LC-MS/MS for mycotoxin determination. Future studies should attempt to use these methods for mass spectrometry imaging (MSI) to evaluate spatial distribution and depth of mycotoxin penetration into building materials.

This study aimed to detect and quantify mycotoxins on building materials using innovative laser mass spectroscopy methods—silver-109/silver/gold nanoparticle-enhanced target surface-assisted laser desorption/ionisation mass spectrometry (109AgNPs, AgNPs and AuNPs SALDI). Results from SALDI-type methods were also compared with commonly used matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Standards of seven moulds mycotoxin in a final concentration of 100 µg/mL for patulin, citrinin, 3-nitropropionic acid, alternariol and 20 µg/mL for sterigmatocystin, cyclopiazonic acid, roquefortine C in the mixture were tested in pure solutions and after extraction from the plasterboards. Among the studied SALDI-type method, the lowest detection limits and the highest signal intensity of the mycotoxins tested were obtained with the use of 109AgNPs SALDI MS. The 109AgNPs method may be considered as an alternative to the currently most frequently used method MALDI MS and also liquid chromatography tandem mass spectrometry LC-MS/MS for mycotoxin determination. Future studies should attempt to use these methods for mass spectrometry imaging (MSI) to evaluate spatial distribution and depth of mycotoxin penetration into building materials.

The development of a sample substrate with superior performance for desorption and ionization of analyte is the key issue to ameliorate the quality of mass spectra for measurements of small molecules in surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Herein, the homogeneous sample substrate of gold nanoparticle multilayers (AuNPs-ML) with hexagonal lattice was successfully prepared by self-assembly technique. With strong surface plasmon resonance absorption and superior photothermal effect, the sample substrate of AuNPs-ML exhibited high signal sensitivity and low background noise for the detection of model analyte of glucose without additional matrixes in SALDI-MS. Furthermore, compared to merchant matrixes of α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB), the sample substrate of AuNPs-ML was demonstrated to ameliorate the quality of mass spectra, including signal strength, background interference and signal/noise (S/N) ratio. The sucrose and tryptophan were also measured to show the extensive applications of AuNPs-ML sample substrate for the detections of small molecules in SALDI-MS. Most importantly, the remarkable reproducibility of glucose mass spectra with relative signal of 7.3% was obtained by the use of AuNPs-ML sample substrate for SALDI-MS. The homogeneous sample substrate of AuNPs-ML greatly improved the quality of mass spectra because of its strong absorption of laser energy, low specific heat, high heat conductivity and extraordinary homogeneity. We believe that AuNPs-ML could be a practical sample substrate for small molecule detection in SALDI-MS.

In this investigation, parameters of electrophoretic deposition (EPO) of TiO2 nanoparticles on stainless steel substrate have been optimized. The obtained coating was used as ion emitter during surface-assisted laser desorpion/ionization (SALDI). Herein, we demonstrate the high efficiency of obtained coatings for SALDI of amiodarone with subsequent Fourier transform ion cyclotron resonance mass spectrometry. Additional modification of coatings with polydimethylsiloxane (PDMS) allowed to significantly improve the sensitivity of SALDI-MS analysis.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF MS) is a commonly used technique for analyzing large biomolecules. However, the utilization of organic matrices limits the small-molecule analysis because of the interferences in the low-mass region and the reproducibility issues. To overcome these limitations, a surface-assisted laser desorption/ionization (SALDI), which utilizes nanostructured metallic surfaces, has been developed. Herein, a novel approach for SALDI–MS was proposed using silica@gold core–shell hybrid materials with a nanogap-rich shell (SiO2@Au NGS), which is an emerging material due to its excellent heat-generating capabilities. The gold shell thickness was controlled by adjusting the concentration of gold precursor for the growth of gold nanoparticles. SALDI-MS measurements were performed on a layer formed by drop-casting a mixture of SiO2@Au NGS and analytes. At the optimized process, the gold shell thickness was observed to be 17.2 nm, which showed the highest absorbance. Based on the enhanced SALDI capability, SiO2@Au NGS was utilized to detect various small molecules, including amino acids, sugars, and flavonoids, and the ionization softness was confirmed with a survival yield upon fragmentation. The limits of detection, reproducibility, and salt tolerance of SiO2@Au NGS demonstrate its potential as an effective and reliable SALDI material for small-molecule analyses.

Iron oxide nanoparticles were applied to the surface-assisted laser desorption and ionization–mass spectrometry (SALDI–MS) of small-molecule compounds, such as oligosaccharides, phytohormones, flavonoids, triglycerides, phospholipids, and amino acids. The spatial distribution of small-molecule compounds in soybean was further studied by using imaging mass spectrometry. After different preparation methods were compared, iron oxide nanoparticles calcined at 300 °C were selected. Results showed that in SALDI–MS analysis, iron oxide nanoparticles were characterized by good stability and low background noise. Analysis was performed in the positive ion mode at the laser energy of 70% with the average spectrum accumulated 30 times. The results showed that iron oxide nanoparticles had good repeatability and sensitivity in the analysis of the abovementioned small-molecule compounds. Four samples, namely, sucrose, abscisic acid, DL-aspartic acid, and 1,2-dipalmitoyl-sn-glycerol-3-phosphorylcholine, were analyzed via SALDI–MS. The spot-to-spot repeatability RSD was less than 2.8%, and the interpoint repeatability RSD was less than 5.2%. The linear correlation coefficient of the four samples was R2 > 0.993 within the concentration range of 0.05–1.0 mg/mL. On the basis of these results, the distribution of small-molecule components in soybean cotyledon, radicle, and germ was analyzed through SALDI–MSI.

Despite improvements in treatment options for advanced colorectal cancer (CRC), survival outcomes are still best for patients with non-metastasised disease. Diagnostic tools to identify blood-based biomarkers and assist in CRC subtype classification could afford a means to track CRC progression and treatment response. Cancer cell-derived small extracellular vesicles (EVs) circulating in blood carry an elevated cargo of lipids and proteins that could be used as a signature of tumour suppressor/promoting events or stages leading up to and including metastasis. Here, we used pre-characterised biobanked plasma samples from surgical units, typically with a low volume (~100 µL), to generate and discover signatures of CRC-derived EVs. We employed nanostructured porous silicon (pSi) surface assisted-laser desorption/ionisation (SALDI) coupled with high-resolution mass spectrometry (HR-MS), to allow sensitive detection of low abundant analytes in plasma EVs. When applied to CRC samples, SALDI-HR-MS enabled the detection of the peptide mass fingerprint of cancer suppressor proteins, including serine/threonine phosphatases and activating-transcription factor 3. SALDI-HR-MS also allowed the detection of a spectrum of glycerophospholipids and sphingolipid signatures in metastatic CRC. We observed that lithium chloride enhanced detection sensitivity to elucidate the structure of low abundant lipids in plasma EVs. pSi SALDI can be used as an effective system for label-free and high throughput analysis of low-volume patient samples, allowing rapid and sensitive analysis for CRC classification.

La caracterització in situ de la composició molecular dels teixits biològics és indispensable en la investigació clínica, farmacèutica i forense. Les tècniques d’imatge molecular, com l’espectrometria de masses d’imatge i les imatges per espectroscòpia Raman, empren materials nanoestructurats per abordar reptes com la baixa sensibilitat, l’especificitat i la resolució lateral. L’objectiu d’aquesta tesi és dissenyar, fabricar, avaluar i aplicar un substrat nanoestructurat basat en or i silici (que denominem “AuBSi”) compatible amb aplicacions d’espectrometria de masses d’imatges per desorció/ionització per làser assistides per superfície (SALDI-MS) i espectroscòpia Raman intensificada per superfície (SERS). Els resultats demostren que el substrat AuBSi és reproduïble, fàcil de fer servir, rendible i altament fiable. Assegura una fàcil preparació de la mostra i és totalment compatible amb les dues modalitats d’imatge, cosa que permet un enfocament veritablement multimodal. Mostrem que hi ha una unificació entre els formats de dades SALDI i SERS que permet la integració completa del flux de treball de processament d’imatges i el co-registre d’imatges.. S’han provat les capacitats d’obtenció d’imatges del substrat AuBSi en diverses solucions d’estàndards, seccions histològiques de teixit animal (fetge, ronyó i cervell de ratolí) i empremtes dactilars. L’anàlisi multimodal d’empremtes dactilars va destacar les excel·lents capacitats del substrat per acoblar imatges SALDI i SERS, alhora que s’aconsegueix pal·liar les limitacions de cada tècnica. Així doncs, el substrat AuBSi desenvolupat en aquesta tesi facilita els estudis de metabolòmica in situ dirigits i/o no dirigits per a diversos camp com la investigació clínica, medioambiental, forense i farmacèutica.
La caracterización in situ de la composición molecular de los tejidos biológicos es indispensable en la investigación clínica, farmacéutica y forense. Las técnicas de imagen molecular, como la espectrometría de masas de imagen y las imágenes por espectroscopia Raman, emplean materiales nanoestructurados para abordar desafíos como la baja sensibilidad, la especificidad y la resolución lateral. El objetivo de esta tesis es diseñar, fabricar, evaluar y aplicar un sustrato nanoestructurado basado en oro y silicio (que denominamos “AuBSi”) compatible con aplicaciones de espectrometría de masas de imágenes por desorción / ionización por láser asistidas por superficie (SALDI-MS) y espectroscopía Raman intensificada por superficie (SERS). Los resultados demuestran que el sustrato AuBSi es reproducible, fácil de usar, rentable y altamente confiable. Garantiza una fácil preparación de la muestra y es totalmente compatible con ambas modalidades de imagen, lo que permite un enfoque verdaderamente multimodal. Mostramos que existe una unificación entre los formatos de datos SALDI y SERS, que permite la integración completa del flujo de trabajo de procesamiento de imágenes y el coregistro de imágenes.Se han probado las capacidades de obtención de imágenes del sustrato AuBSi en varias soluciones de estándares, secciones histológicas de tejido animal (hígado, riñón y cerebro de ratón) y huellas dactilares. El análisis multimodal de huellas dactilares destacó las excelentes capacidades del sustrato para acoplar imágenes SALDI y SERS, al tiempo que se consiguen paliar las limitaciones de cada técnica. Así, el sustrato AuBSi desarrollado en esta tesis facilita los estudios de metabolómica in situ dirigidos y / o no dirigidos para diversos campos como la investigación clínica, medioambiental, forense y farmacéutica.
Characterising in situ the molecular composition of biological tissues is an indispensable tool in clinical, pharmaceutical and forensic research. Imaging modalities such as mass spectrometry imaging and Raman spectroscopy imaging employ nanostructured materials for addressing challenges such as low sensitivity, specificity and lateral resolution. The aim of this thesis is to design, fabricate, evaluate and apply a gold- and silicon-based nanostructured substrate (named AuBSi) compatible with surface-assisted laser desorption/ionization (SALDI) and surface-enhanced Raman spectroscopy (SERS) imaging applications. Results demonstrate that the AuBSi substrate is reproducible, user-friendly, cost effective and highly reliable. It ensures easy sample preparation and is fully compatible with both imaging modalities, enabling a genuine multimodal approach. We show that there is a unification between SALDI and SERS data formats that allows the full integration of the image processing workflow and the straightforward coregistration of images. We tested the imaging capabilities of the AuBSi on several standard solutions, animal tissue sections (mouse liver, kidney and brain) and fingerprints. The multimodal analysis of fingerprints highlighted the excellent capabilities of the substrate to couple SALDI and SERS imaging, while dealing with the challenges of each technique. Thus, the AuBSi substrate developed in this thesis facilitates targeted and/or untargeted in situ metabolomics studies for various fields such as clinical, environmental, forensics, and pharmaceutical research.

Les maladies neurodégénératives sont des maladies chroniques progressives touchant le système nerveux central. Tandis que ces maladies ont des origines multifactorielles, leur fréquence augmente avec l'âge. En raison du vieillissement progressif de la population, et de l'absence de traitement, elles deviennent un enjeu majeur de santé publique. Pour exemple, la maladie d'Alzheimer pourrait toucher 1 personne dans le monde sur 85 d'ici 2050. C'est dans ce contexte que les chercheurs étudient différentes pistes pour permettre une meilleure compréhension de cette maladie et de ses mécanismes pathophysiologies. Ils savent aujourd'hui qu'une hyperphosphorylation de la protéine Tau et la production de formes toxiques de peptides beta-amyloïdes s'agglomérant en plaques séniles en sont les principales causes. L'origine de ces dysfonctionnements est quant à elle encore mal connue mais pourrait être élucidée par l'étude des mécanismes biochimiques intracellulaire. Dans ce contexte, nous avons imaginé un dispositif in vitro reposant sur l'utilisation de nanoaiguilles en silicium ayant la faculté de sonder le cytoplasme cellulaire de neurones pour y détecter les biomarqueurs de l'Alzheimer et en suivre l'évolution. Notre travail a reposé sur l'élaboration de ce capteur qui s'est divisée en 3 points. Le premier était la fabrication des nanoaiguilles par développement de techniques peu onéreuse comme la lithographie de nanosphère suivit de méthodes de gravure humide ou sèches. Le second point était l'optimisation de ces aiguilles pour l'identification bimodale de molécules par spectrométrie de masse (SALDI-MS) et par spectrométrie Raman exaltée de surface (SERS). Le troisième point portait sur l'étude de l'interaction entre nos aiguilles et les neurones avec à l'esprit la volonté de capture de biomarqueurs et la préservation de l'intégrité cellulaire. La lithographie de nanosphères a pu être développée, et les aiguilles ont été fabriquées selon 2 voies que sont la gravure humide assistée par métal (MACE) et la gravure sèche par gravure plasma continue. De la rhodamine 6G, des peptides standards ainsi que des peptides beta-amyloïdes ont pu être détectés par SALDI-MS et SERS sur nos réseaux d'aiguilles. Enfin nous avons constaté la biocompatibilité de nos aiguilles avec le milieu cellulaire et caractérisé leur interaction
Neurodegenerative diseases are chronic progressive diseases affecting the central nervous system. While these diseases have multifactorial origins, their prevalence increases with age. Due to the progressive aging of the population and the absence of treatment, they are becoming a crucial public health issue. For example, Alzheimer's disease will affect 1 person out of 85 worldwide by 2050. In this context, researchers are studying various options to gain a better understanding of this disease and its pathophysiological mechanisms. They now know that hyperphosphorylation of the Tau protein and the production of toxic forms of beta-amyloid peptides that aggregate into senile plaques are the main causes. The origin of these dysfunctions is still poorly understood but could be elucidated by studying intracellular biochemical mechanisms. In this context, we have conceived an in vitro device based on the use of silicon nanoneedles with the ability to probe the cytoplasm of neuronal cells to detect Alzheimer's biomarkers and monitor their evolution. Our work was based on the development of this sensor, which was divided into 3 points. The first was the fabrication of nanoneedles through the development of cost-effective techniques such as nanosphere lithography followed by wet or dry etching methods. The second point was the optimization of these needles for the bimodal identification of molecules by mass spectrometry (SALDI-MS) and surface-enhanced Raman spectroscopy (SERS). The third point focused on the study of the interaction between our needles and neurons with the aim of capturing biomarkers and preserving cellular integrity. Nanosphere lithography was successfully developed, and the needles were manufactured using two methods: metal assisted chemical etching (MACE) and dry etching by continuous plasma etching. Rhodamine 6G, standard peptides, and beta-amyloid peptides could be detected by SALDI-MS and SERS on our needle arrays. Finally, we observed the biocompatibility of our needles with the cellular environment and characterized their interaction

Analysis of compounds present in complex matrices is always a challenge, which can be partly overcome by applying various sample preparation techniques prior to detection. Ideally, the extraction techniques should be as selective as possible, to minimize the concentration of interfering substances. In addition, results can be improved by efficient chromatographic separation of the sample components. The elimination of interfering substances is especially important when utilizing mass spectrometry (MS) as a detection technique since they influence the ionization yields. It is also important to optimize ionization methods in order to minimize detection limits. In the work this thesis is based upon, selective solid phase extraction (SPE) materials, a restricted access material (RAM) and graphitized carbon black (GCB) were employed for clean up and/or pre-concentration of analytes in plasma, urine and agricultural drainage water prior to liquid chromatography/mass spectrometry (LC/MS). Two SPE formats, in which GCB was incorporated in µ-traps and disks, were developed for cleaning up small and large volume samples, respectively. In addition, techniques based on use of sub-2 µm C18 particles at elevated temperatures and a linear ion trap (LIT) mass spectrometer were developed to improve the efficiency of LC separation and sensitivity of detection of 6-formylindolo[3,2-b]carbazole (FICZ) metabolites in human urine. It was also found that GCB can serve not only as a SPE sorbent, but also as a valuable surface for surface-assisted laser desorption ionization (SALDI) of small molecules. The dual functionality of GCB was utilized in a combined screening-identification/quantification procedure for fast elimination of negative samples. This may be particularly useful when processing large numbers of samples. SALDI analyses of small molecules was further investigated and improved by employing two kinds of new surfaces: oxidized GCB nanoparticles and silicon nitride.

Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization method used in mass spectrometry that is important for the analysis of biomolecules and large synthetic molecules. However, it is difficult to use MALDI for the analysis of small molecules because the matrix ions interfere with their analysis. Several surface-assisted laser desorption/ionization (SALDI) mass spectrometry methods have been developed as a solution to this problem. In this thesis, polylactide (PLA) nanocomposites containing halloysite nanoclay, hydroxyapatite, magnesium oxide, montmorillonite nanoclay, silicon dioxide, silicon nitride, titanium dioxide, and graphitized carbon black (GCB) nanoparticles were examined as surfaces for SALDI. The intensities of the signals of three human medicines: acebutolol, carbamazepine, and propranolol, obtained from these surfaces were compared to the signal intensities obtained from stainless steel MALDI plate without use of any matrix. The signal intensity was only enhanced when nanocomposites containing 30% GCB, 10% silicon nitride, and 10% titanium dioxide nanoparticles and analytes in concentration of 150 ppm were used. These results, together with the fact that PLA is a biodegradable polymer and can be obtained from renewable resources, make these materials potential...