Bridging the gap between molecular and elemental mass spectrometry: Higher energy collisional dissociation (HCD) revealing elemental information

Molecular mass spectrometry has been applied to simultaneously obtain molecular and elemental information from metal-containing species. Energy tuning of the higher-energy collision dissociation (HCD) fragmentation cell allows the controlled production of typical peptide fragments or elemental reporter ions informing about the metallic content of the analyzed species. Different instrumental configurations and fragmentation techniques have been tested, and the efficiency extracting the elemental information has been compared. HCD fragmentation operating at very high energy led to the best results. Platinum, lanthanides, and iodine reporter ions from peptides interacting with cisplatin, peptides labeled with lanthanides-MeCAT-IA, and iodinated peptides, respectively, were obtained. The possibility to produce abundant molecular and elemental ions in the same analysis simplifies the correlation between both signals and open pathways in metallomics studies enabling the specific tracking of metal-containing species. The proposed approach has been successfully applied to in solution standards and complex samples. Moreover, interesting preliminary MALDI-imaging experiments have been performed showing similar metal distribution compared to laser ablation (LA)-ICPMS

A multi-parametric microarray for protein profiling: simultaneous analysis of 8 different cytochromes via differentially element tagged antibodies and laser ablation ICP-MS.

The paper presents a new multi-parametric protein microarray embracing the multi-analyte capabilities of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The combination of high throughput reverse phase protein microarrays with element tagged antibodies and LA-ICP-MS makes it possible to detect and quantify many proteins or biomarkers in multiple samples simultaneously. A proof of concept experiment is performed for the analysis of cytochromes particularly of cytochrome P450 enzymes, which play an important role in the metabolism of xenobiotics such as toxicants and drugs. With the aid of the LA-ICP-MS based multi-parametric reverse phase protein microarray it was possible to analyse 8 cytochromes in 14 different proteomes in one run. The methodology shows excellent detection limits in the lower amol range and a very good linearity of R(2) ≥ 0.9996 which is a prerequisite for the development of further quantification strategies

Screening of selenium containing proteins in the Tris-buffer soluble fraction of African catfish (Clarias gariepinus) fillets by laser ablation-ICP-MS after SDS-PAGE and electroblotting onto membranes

The anti-carcinogenic properties of selenium against certain types of cancer when present in organic forms justify the increasing interest in development of selenium fortified food. In this particular study, African catfish (Clarias gariepinus) were fed with a Se-enriched diet in order to enhance the selenium concentration in the fish fillet up to 0.85 ± 0.06 mg Se kg-1 (0.26 ± 0.02 mg Se kg-1 in control). Selenium distribution in proteins separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was studied for better understanding of the metabolism of this element in the organism. Soluble proteins (Tris buffer) were investigated by conventional application of a glass homogenizer in comparison to application of ultrasound probe sonication, and the latter was convincing due to higher protein extraction efficiency and the ease and speed of application. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was successfully applied for screening of selenium in proteins in fillets of African catfish separated by one-dimensional SDS-PAGE and after electroblotting onto nitrocellulose membranes, with a total Se amount below 0.4 ng loaded into a well. Selenium was detected in more than 11 protein spots. In order to improve the protein separation of one-dimensional SDS-PAGE, pre-fractionation of the Tris buffer soluble protein extract by size exclusion was carried out. Tryptic digestion of the Se-containing bands was performed for protein identification by nano-HPLC coupled to electrospray-MS/MS. A database search revealed several proteins which are located in muscle tissue. However, the very low Se concentration circumvents the detection of selenium containing amino acids in the tryptic peptides by electrospray-MS/M

Covalent Trapping of Cyclic-Polysulfides in Perfluorinated Vinylene-Linked Frameworks for Designing Lithium-Organosulfide Batteries

The strategic combination of redox-active triazine- or quinoxaline-based lithium-ion battery (LIB) mechanisms with the polysulfide ring-mediated lithium-sulfur battery (Li-SB) mechanism enabled the configuration of covalent organic-framework (COF)-derived lithium-organosulfide (Li-OrSB) battery systems. Two vinylene-linked frameworks were designed by enclosing polysulfide rings via postsynthetic framework sulfurization, allowing for the separate construction of triazine-polysulfide and quinoxaline-polysulfide redox couples that can readily interact with Li ions. The inverse vulcanization of the vinylene linking followed by the sulfurization-induced nucleophilic aromatic substitution reaction (SNAr) on the perfluorinated aromatic center of the COFs enabled the covalent trapping of cyclic-polysulfides. The experimentally observed reversible Li-interaction mechanism of these highly conjugated frameworks was computationally verified and supported by in situ Raman studies, demonstrating a significant reduction of polysulfide shuttle in a conventional Li-SB and opening the door for a COF-derived high-performing Li-OrSB