Functionalized Porous Silicon Surfaces as DESI-MS Substrates for Small Molecules Analysis

Abstract

In desorption electrospray ionization mass spectrometry (DESI-MS), the type of surface in addition to low gas and solvent flow rates help to avoid the "splashing of solvent" or "washing effect", by which samples are promptly removed from the surface by the spray. These effects operate on smooth surfaces and generally result in unstable signals as the spray moves over the spot. The aim of this work is to compare the performance of functionalized porous silicon surfaces (pSi) for small molecules analysis with regard to the stability of the signal and the limits of detection (LODs) observed in DESI-MS. The results showed that functional groups, like 1-decene and heptadecafluoro-1,1,2,2-tetrahydrodecyl trimethoxysilane, on pSi surface provides a good alternative for dried spot analysis by DESI-MS, improving stability of the signal and the LODs. This improvement is possible because the dual process containing the weak sample-surface interactions of the hydrophobic characteristic of the functional groups and increasing the surface area of interaction between the sample and the thin solvent film created by the DESI spray, resulting in more effective dissolution of the analyte in the spray solvent without fast removal of the sample.

Evaluation of imprint DESI-MS substrates for the analysis of fungal metabolites

“…The porosity avoids the sample from being swily washed away from the surface, thus making the desorption of the ions more efficient. 32,35 In fact, the surface porosity might act as a barrier that traps the imprinted molecules, avoiding the spreading and instant removal of the sample while improving the quality of the spectra. Tape and lter paper gave an averaged TIC of 7 Â 10¹ (Fig.…”

“…The porous silicon substrates (pSi) were prepared using silicon wafers from Virginia Semiconductors Inc. (Fredericksburg, Virginia, USA), as described before. 32 Briey, both the mesoporous substrates were galvanostatically etched with a mixture of hydrouoric acid (HF) (49%, Sigma-Aldrich) and anhydrous ethanol (USP grade, commercial alcohol, from Sigma-Aldrich.) in a home-made Teon etch cell using a PAR HD potentiostat-galvanostat.…”

“…The diameters of the porous samples were between 2 and 50 nm. 32 The porous samples produced in this way were originally hydrogen terminated but since they were handled in ambient conditions and submitted to aqueous solutions, it is believed that they were likely oxidized during the experimentation with DESI-MS.…”

Build, Share and Remix: 3D Printing for Speeding Up the Innovation Cycles in Ambient Ionisation Mass Spectrometry (AIMS)

“…The sample support material affects the reproducibility and sensitivity of DESI analyses. Polytetrafluoroethylene (PTFE) is commonly used; alternative materials such as polymethylmethacrylate (PMMA) [62] and silicon [63] were used for the analysis of plant and animal tissues.…”

The Imprinted PARAFILM as a New Carrier Material for Dried Plasma Spots (DPSs) Utilizing Desorption Electrospray Ionization Mass Spectrometry (DESI-MS) in Phospholipidomics

“…Various attempts have been made to produce the highest signal and the least ionization suppression (Leuthold et al, 2006;Wiseman et al, 2010). An increasing number of commercial or homemade substrates, including silicon-based materials, such as glass slides (Pasilis et al, 2007;Manicke et al, 2008) and glass slides coated with heavy Teflon coating (HTC) material (Mattarozzi et al, 2012), and thin-layer chromatographic plates (Kauppila et al, 2006), porous silicon chips (Schwab et al, 2014), and carbon-based materials, such as polymethyl methacrylate (Volny et al, 2008), PTFE (Manicke et al, 2008;Volny et al, 2008), PTFE-printed glass (Manicke et al, 2008), paper (Manicke et al, 2008) and porous Teflon membranes (Rosting et al, 2013;Sero et al, 2015), have been investigated for DESI-MS analysis. From these studies, we have concluded that an electrically nonconductive material could enhance the response of DESI-MS since the material preserves charges by avoiding neutralization of the incoming ion plume at the surface.…”