Mechanisms of nanophase-induced desorption in LDI-MS. A short review

Nanomaterials are frequently used in laser desorption ionization mass spectrometry (LDI-MS) as DI enhancers, providing excellent figures of merit for the analysis of low molecular weight organic molecules. In recent years, literature on this topic has benefited from several studies assessing the fundamental aspects of the ion desorption efficiency and the internal energy transfer, in the case of model analytes. Several different parameters have been investigated, including the intrinsic chemical and physical properties of the nanophase (chemical composition, thermal conductivity, photo-absorption efficiency, specific heat capacity, phase transition point, explosion threshold, etc.), along with morphological parameters such as the nanophase size, shape, and interparticle distance. Other aspects, such as the composition, roughness and defects of the substrate supporting the LDI-active nanophases, the nanophase binding affinity towards the target analyte, the role of water molecules, have been taken into account as well. Readers interested in nanoparticle based LDI-MS sub-techniques (SALDI-, SELDI-, NALDI- MS) will find here a concise overview of the recent findings in the specialized field of fundamental and mechanistic studies, shading light on the desorption ionization phenomena responsible of the outperforming MS data offered by these techniques

MALDI Mass Spectrometry: A Promising Non-Chromatographic Technique

In recent years, food safety and quality have become of great importance and have involved more public concern. Food quality is associated to food authentication and adulteration, or food features that include ingredients and/or additives as antioxidants and chemicals used to improve food taste, aroma and colour. Food safety is concerned with food contaminants and residues as pesticides, veterinary drugs, environmental contaminants, food processing and food packaging contaminants. As a result, demand for the development and the applications of more efficient methodologies to analyze food is significantly growing. In this perspective, a new discipline named foodomics has been recently introduced which applies advanced ‐omic sciences (genomics, proteomics, lipidomics, etc.) in food and nutrition fields for compound profiling, authenticity, food quality or safety, food bioactivity, toxicity issue and so on. Of course, for foodomics studies, mass spectrometry (MS) is considered an indispensable technique due to its intrinsic features, i.e. high sensitivity, selectivity and throughput. Among MS techniques, Matrix Assisted Laser Desorption Ionization (MALDI) has demonstrated a great potential in fast screening analyses for food quality and safety, since no chromatographic separation is usually needed. In this chapter, some MALDI MS quality control applications will be presented, based on proteomic and lipidomic approaches or devoted to the individuation of food contaminants

Lipid fingerprinting of Gram-positive lactobacilli by intact cells - Matrix-assisted laser desorption/ionization mass spectrometry using a proton sponge based matrix

A method of direct lipid analysis by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) in intact membranes, without prior extraction/separation steps, is described. Here, we demonstrate the efficacy of a strong base, 1,8-bis(dimethylamino)naphthalene (DMAN; proton sponge), as a novel matrix for MALDI-time-of-flight (TOF) MS analysis of whole cell bacteria. Initially, individual acidic low-molecular-weight analytes such as standard free fatty acids and phospholipids were analyzed using DMAN as matrix. Clear negative-mode MALDI-TOF MS spectra of all analytes show only deprotonated analyte signals at a low picomole limit of detection with the complete absence of matrix-related signals. These results indicate that DMAN represents a suitable matrix for MALDI-TOF MS analysis of mixtures of complex lipids as the intact membranes of microorganisms. DMAN was successfully applied to the analysis of Lactobacillus sanfranciscensis and L. plantarum microorganisms. Different components were sensitively detected in a single spot, including 16:0, 18:2, 18:3, and 21:0 free acids, glycolipids, phosphatidylglycerols (PGs) and cardiolipins. This method might be of general application, offering the advantage of quickly gaining information about lipid components of other Gram-positive bacterial membranes

Editorial to the Special Issue “Lipidomics and Neurodegenerative Diseases”

The contribution of dysregulation of lipid signaling and metabolism to neurodegenerative diseases including Alzheimer’s and Parkinson’s is the focus of this special issue. Here, the matter of three reviews and one research article is summarized