Matrix‐free methods for laser desorption/ionization mass spectrometry

Peterson, Dominic S.

doi:10.1002/mas.20104

Cited by 284 publications

(253 citation statements)

References 76 publications

(64 reference statements)

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“…Moreover, using a chemical reduction and alkylation strategy, thiol and disulphide absence has been confirmed in a gliotoxin-like metabolite isolated from an A. fumigatus mutant deficient in gliotoxin biosynthesis [17]. To date, matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-ToF MS) has not been used for the detection of gliotoxin, as matrix components can interfere with the detection of low molecular mass metabolites and gliotoxin fragments during ionisation, thereby rendering detection impossible [16,18].…”

Section: Introductionmentioning

confidence: 99%

Single-pot derivatisation strategy for enhanced gliotoxin detection by HPLC and MALDI-ToF mass spectrometry

et al. 2011

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Gliotoxin is produced by non-ribosomal peptide synthesis and secreted from certain fungi, including Aspergillus fumigatus. It is an epipolythiodioxopiperazine that contains an intact disulphide bridge and is the focus of intense research as a consequence of its negative immunomodulatory properties. Gliotoxin detection is generally enabled by reversed-phase-high-performance liquid chromatography (RP-HPLC), with absorbance detection (220-280 nm), or liquid chromatography-mass spectrometry, yet detection is not readily achievable by matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-ToF MS). We have developed a single-pot derivatisation strategy which uses sodium borohydride-mediated reduction of gliotoxin followed by immediate alkylation of exposed thiols by 5′-iodoacetamidofluorescein to yield a stable product, diacetamidofluorescein-gliotoxin (GT-(AF) 2 ), of molecular mass 1103.931 Da ((M+H)+). This product is readily detectable by RP-HPLC and exhibits a 6.8-fold increase in molar absorptivity compared with gliotoxin, which results in a higher sensitivity of detection (40 ng; 125 pmoL). GT-(AF) 2 also fluoresces (excitation/emission, 492:518 nm). Unlike free gliotoxin, the product (>800 fmol) is detectable by MALDI-ToF MS. Sporidesmin A can also be detected by RP-HPLC and MALDI-ToF MS (>530 fmol) using this strategy. We also demonstrate that the strategy facilitates detection of gliotoxin (mean± SD = 3.55 ± 0.07 μg 100 μL −1 ; n = 2) produced by A. fumigatus, without the requirement for organic extraction of culture supernatants and associated solvent removal. GT-(AF) 2 is also detectable (150 ng; 460 pmol) by thinlayer chromatography.

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Section: Introductionmentioning

confidence: 99%

Single-pot derivatisation strategy for enhanced gliotoxin detection by HPLC and MALDI-ToF mass spectrometry

et al. 2011

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“…Inspired by Tanaka's results, a series of inorganic micro-and nanomaterials-such as graphite particles [9], gold NPs (AuNPs) [10], silver NPs [11], titanium dioxide NPs [12], silicon NPs [13], Au nanorods [14], and carbon nanotubes [15]-have been studied as potential inorganic matrices. Moreover, matrix-free LDI-MS has been proposed using porous silicon as a sample target for the analysis of small molecules such as peptides, drugs, surfactants, and carbohydrates [16]. This well-known technique is called desorption/ionization on porous silicon (DIOS) [17].…”

mentioning

confidence: 99%

“…This well-known technique is called desorption/ionization on porous silicon (DIOS) [17]. In addition to DIOS, other approaches, including sol-gels, carbon-based microstructures, silicon nanowire-based silicon wafers, or germanium nanodot-based chips [16,18], have been used in matrix-free LDI-MS.…”

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confidence: 99%

Gold nanoparticles as assisted matrices for the detection of biomolecules in a high-salt solution through laser desorption/ionization mass spectrometry

Lin

et al. 2009

J. Am. Soc. Mass Spectrom.

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Citrate-capped gold nanoparticles (AuNPs) serve as matrices for the determination of biomolecules in a high-salt solution through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In the case of using 2,5-dihydroxybenzoic acid (2,5-DHB) as a matrix, the signal intensities of neutral steroids were severely suppressed in a high-salt solution. A high concentration of NaCl caused the formation of the sodium adduct ions during the desorption/ionization process, resulting in a decrease of the signal intensities of the protonated ions. In comparison, by applying AuNP-assisted LDI-TOF-MS, the signal intensities of neutral steroids remained almost constant when the concentration of NaCl was increased to 500 mM. Because the use of citrate-capped AuNPs as matrices primarily offers alkali metal ion adducts, AuNP matrices have a higher tolerance to high NaCl concentrations relative to that of 2,5-DHB matrices. The relevant phenomena are also discovered in the case of analysis of neutral carbohydrate, monosialoganglioside, indolamine, and angiotensin I. The quantification of small molecules in a high-salt solution has been accomplished by AuNP-assisted LDI-TOF-MS coupled to a unique sample preparation, in which samples are deposited onto the sample plate before AuNPs. The present method has been further applied to the determination of urea, creatinine, uric acid, and glucose in a urine sample. (J Am Soc Mass Spectrom 2009, 20, 875-882)

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“…Various inorganic materials have been applied for MS analysis, including cobalt powder, graphite powder, porous silicon surface, and metal particles [8]. SALDI not only improves the reproducibility of MS analysis but also reduces the background signals of the organic matrix ions in the low-mass range [9,10].…”

mentioning

confidence: 99%

CHCA-modified Au nanoparticles for laser desorption ionization mass spectrometric analysis of peptides

Duan

Linman

Chen

et al. 2009

J. Am. Soc. Mass Spectrom.

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Gold nanoparticles (AuNPs) have been studied as a potential solid-state matrix for laser desorption/ionization mass spectrometry (LDI-MS) but the efficiency in ionization remains low. In this report, AuNPs are capped by a self-assembled monolayer of cysteamine and modified with ␣-cyano-4-hydroxycinnanic acid (CHCA) for effective MALDI measurements. CHCA-terminated AuNPs offer marked improvement on peptide ionization compared with citrate-capped or cysteamine-capped AuNPs. The coating also effectively suppresses formation of Au cluster ions and analyte fragment ions, leading to cleaner mass spectra. Addition of glycerol and citric acid to the peptide/AuNPs sample further improves the performance of these AuNPs for LDI-MS analysis. Glycerol appears to enhance the dispersion of AuNPs in sample spots, increasing the sample ionization and shot-to-shot reproducibility, while citric acid serves as an external proton donor, providing high production of protonated analyte ions and reducing fragmentation of peptides on the nanoparticle-based surface. Optimal ratios of citric acid, glycerol, and AuNPs in sample solution have been systematically studied. A more than 10-fold increase for desorption ionization of peptides can be achieved by combining 5% glycerol and 20 mM citric acid with the CHCA-terminated AuNPs. The applicability of the CHCA-AuNPs for LDI-MS analysis of protein digests has also been demonstrated. This work shows the potential of AuNPs for SALDI-MS analysis, and the improvement with chemical functionalization, controlled dispersion, and use of an effective proton donor. (J Am Soc Mass

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Matrix‐free methods for laser desorption/ionization mass spectrometry

Cited by 284 publications

References 76 publications

Single-pot derivatisation strategy for enhanced gliotoxin detection by HPLC and MALDI-ToF mass spectrometry

Single-pot derivatisation strategy for enhanced gliotoxin detection by HPLC and MALDI-ToF mass spectrometry

Gold nanoparticles as assisted matrices for the detection of biomolecules in a high-salt solution through laser desorption/ionization mass spectrometry

CHCA-modified Au nanoparticles for laser desorption ionization mass spectrometric analysis of peptides

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