Interfacial Tension of the Lipid Membrane Formed from Phosphatidylcholine–Decanoic Acid and Phosphatidylcholine–Decylamine Systems

Interfacial tension has been determined for phosphatidylcholine (PC)–decanoic acid (DA) and PC–decylamine (DE) membranes. PC (lecithin), DA and DE were used in the experiments; the interfacial tension values of the pure components are 1.62 × 10−3, −2.38 × 10−2 and −3.88 × 10−2 N/m (hypothetical values for DA and DE), respectively. The 1:1 complexes were formed during formation of PC–DA and PC–DE membranes. The following parameters describing the complexes were determined: the surface concentrations of the lipid membranes formed from these complexes, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_{3}^{ - 1}$$\end{document}; the interfacial tensions of such membranes, γ3; and the stability constants of these complexes, K

Acid–base-driven matrix-assisted mass spectrometry for targeted metabolomics

The ability to charge huge biomolecules without breaking them apart has made matrix-assisted laser desorption/ionization (MALDI) mass spectrometry an indispensable tool for biomolecular analysis. Conventional, empirically selected matrices produce abundant matrix ion clusters in the low-mass region (<500 Da), hampering the application of MALDI-MS to metabolomics. An ionization mode of MAILD, a rational protocol for matrix selection based on Brønsted–Lowry acid–base theory and its application to metabolomics, biological screening/profiling/imaging, and clinical diagnostics is illustrated. Numerous metabolites, covering important metabolic pathways (Krebs' cycle, fatty acid and glucosinolate biosynthesis), were detected in extracts, biofluids, and/or in biological tissues (Arabidopsis thaliana, Drosophila melanogaster, Acyrthosiphon pisum, and human blood). This approach moves matrix selection from “black art” to rational design and sets a paradigm for small-molecule analysis via MALDI-MS