Traceless Immobilization of Analytes for High-Throughput Experimenting with SAMDI Mass Spectrometry

Helal, Kazi Yasin

doi:https://doi.org/10.21985/n2-zxh3-4392

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Traceless Immobilization of Analytes for High-Throughput Experimenting with SAMDI Mass Spectrometry

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Label-free assays, and particularly those based on the combination of mass spectroscopy with surface chemistries, enable high-throughput experiments of a broad range of reactions. However, these methods can still require the incorporation of functional groups that allow immobilization of reactants and products to surfaces prior to analysis. In this thesis, we report several means for small molecule analysis. First, we report a traceless method for attaching molecules to a self-assembled monolayer for matrix-assisted laser desorption and ionization (SAMDI) mass spectrometry. This method uses monolayers that are functionalized with a 3-trifluoromethyl-3-phenyl-diazirine group that liberates nitrogen when irradiated and gives a carbene that inserts into a wide range of bonds to covalently immobilize molecules. Analysis of the monolayer with SAMDI then reveals peaks for each of the adducts formed from molecules in the sample. This method is applied to characterize a P450 drug metabolizing enzyme and to monitor a Suzuki–Miyaura coupling chemical reaction and is important because modification of the substrates with a functional group would alter their activities. This method will be important for high-throughput experiments in many areas, including reaction discovery and optimization. The other methods reported in this thesis includes proof of concept for an aptamer and graphene approach to small molecule analysis. The aptamer approach builds on SAMDI by using the aptamers to extract the target analytes for analysis. The graphene approach serves as an alternative surface for direct small molecule analysis using laser/desorption ionization (LDI).

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