Search

The development of sensitive and point-of-care diagnostic tools for the serological profile of numerous Mycobacterium tuberculosis (MTB) rectifies the existing flaws in tuberculosis diagnosis. Here...

The sinapinic acid (SA) matrix has frequently been used for protein analysis in matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). However, the SA matrix does not result in the formation of distinctive multiple protein charge states, whereas the 2-nitrophloroglucinol (2-NPG) matrix is capable of this. The formation of multiple charge states in the MALDI-MS analysis of proteins is advantageous in that it results in higher accuracy. In this study, the mass spectra of several common standard proteins, namely cytochrome c, myoglobin, bovine serum albumin (BSA), and immunoglobulin G (IgG), were compared using various matrices (2,5-dihydroxybenzoic acid, α-cyano-hydroxycinnamic acid, SA, and 2-NPG). Furthermore, the mass spectra of two large standard proteins (BSA and IgG) using various acid additives (H3PO4, HNO3, H2SO4, HCl, and trifluoroacetic acid) with the 2-NPG matrix were also compared. Among the different matrices, 2-NPG provided the broadest range of multiple protein charge states, while, among the different additives, the 2-NPG matrix in combination with HCl generated the broadest multiple charge states as well as the most intense protein peaks.

Disaccharides are sugars composed of two monosaccharides joined by a glycosidic linkage. The specific properties of a disaccharide depend on the type of the glycosidic linkage and the identity of the two component monosaccharides. In this work, seven disaccharide isomers (gentiobiose, isomaltose, melibiose, lactose, maltose, cellobiose, and sucrose) were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) using a graphene oxide matrix. Each disaccharide was identified by its unique cleavage pattern. To determine the feasibility of quantitative analyses based on specific fragment patterns, mixtures of sucrose with cellobiose or maltose were prepared at different ratios and analyzed by MALDI-MS, where a strong linear correlation was observed between the relative peak intensity of the sucrose fragment peak at m/z 185 and the amount of sucrose in the mixture. The calibration curve was successfully applied to obtain the relative amount of maltose and sucrose in four different honey samples.

Decontamination of organophosphorus chemical warfare nerve agents (CWNAs) is gaining importance for human security. Herein, we have employed a dry-photodecontamination method for CWNA model molecules of dimethyl methylphosphonate, dimethyl phosphite, diethyl methylphosphonate, and diethyl phosphite contaminated on aluminum (Al) and oxidized Al foils. For understanding their photo-degradation pathways, the photo-decomposition secondary chemical products generated as a result of UVC-decontamination were fully examined for the contaminated Al and oxidized Al target areas in a closed reactor system by gas chromatography and mass spectrometry. Solid residues were also fully examined by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Density functional theory at the B3LYP/6–31 G level was used for geometric optimization, and the electronic energy state calculation was conducted on the level of TD-SCF/B3LYP/6–31 G. The new results further deepen the photo-decomposition mechanism of CWNAs, the development of dry UV light photo-decontamination methods, and the treatment of secondary by-products.

Exosomes are nanosized vesicles commonly found in biological fluids as a result of a secretion process involving endosomes and multivesicular bodies. The isolation and analysis of exosomes can be useful for noninvasive clinical diagnosis of a variety of human diseases. We investigated the utility of analyzing exosomal proteins, using matrix-assisted laser desorption/ionization combined with Fourier-transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS), as a means of determining the presence of exosomes. MALDI-FTICR-MS analyses of exosomes enriched from human serum via centrifugation in a mass range of

Ultraviolet (UV) laser irradiation was applied to decontaminate chemical warfare agent simulants chloroethyl phenyl sulfide (CEPS) and malathion, with results obtained from gas chromatography–mass spectrometry analysis. Exposure of CEPS to a 266 nm laser exhibited feasible decontamination by dominantly producing the byproduct diphenyl disulfide. However, decontamination in the cases with 355 and 532 nm exposure on CEPS as well as 266 nm exposure on malathion were relatively inefficient. Results also show a strong correlation between decontamination efficiency and absorption probability, which indicates the importance of selecting proper laser wavelengths and supports the photochemical mechanism of UV laser decontamination.