Metal-Organic Framework-Enhanced Solid-Phase Microextraction Mass Spectrometry for the Direct and Rapid Detection of Perfluorooctanoic Acid in Environmental Water Samples

We report the development of metal-organic framework (MOF)-based probes for the direct and rapid detection and quantification of perfluorooctanoic acid (PFOA) by mass spectrometry. Four water-resistant MOFs - ZIF-8, UiO-66, MIL88-A, and Tb2(BDC)3 - were coated on poly(dopamine) precoated stainless steel needles and used to rapidly preconcentrate PFOA from water for direct analysis by nanoelectrospray ionization mass spectrometry. The analytical performance of each MOF for detecting PFOA was correlated with both the calculated binding energy of the MOF for PFOA and the relative change in the surface area of the MOF upon exposure to PFOA. MOF-functionalized probes can be used for the rapid (<5 min) and sensitive quantification of PFOA molecules at low ng L-1 levels in environmental water samples (i.e., tap water, rainwater, and seawater) with no sample preparation. The limit of detection of PFOA in ultrapure water was 11.0 ng L-1. Comparable accuracy to an accredited analytical method was achieved, despite the MOF-functionalized probe approach being 40 times quicker and requiring 10 times less sample. These features indicate that MOF-coated probes are promising for the direct and rapid monitoring of polyfluorinated substances and other pollutants in the field

Design, synthesis, and characterisation of glyoxylamide-based short peptides as self-assembled gels

The synthesis and supramolecular properties of novel glyoxylamide-based short peptides formed via the ring-opening reaction of N-acetylisatins in solution phase are described. The short peptides self-assembled into gels, which were examined for their mechanical and morphological characteristics using multiple spectroscopic and microscopy techniques. The critical gel concentration and mechanical strength of the self-assembled gels were influenced by the presence of electronegative substituents (such as fluoro, in 5b) or hydrophobic substituents (such as bromo, 5d) respectively in the short peptides. Moreover, in vitro cytotoxicity assays demonstrated that these compounds were non-toxic to mammalian cells