Synergistic effect of graphene oxide/MWCNT films in laser desorption/ionization mass spectrometry of small molecules and tissue imaging.

Matrix-assisted laser desorption/ionization mass spectrometry has been considered an important tool for various biochemical analyses and proteomics research. Although addition of conventional matrix efficiently supports laser desorption/ionization of analytes with minimal fragmentation, it often results in high background interference and misinterpretation of the spatial distribution of biomolecules especially in low-mass regions. Here, we show design, systematic characterization, and application of graphene oxide/multiwalled carbon nanotube-based films fabricated on solid substrates as a new matrix-free laser desorption/ionization platform. We demonstrate that the graphene oxide/multiwalled carbon nanotube double layer provides many advantages as a laser desorption/ionization substrate, such as efficient desorption/ionization of analytes with minimum fragmentation, high salt tolerance, no sweet-spots for mass signal, excellent durability against mechanical and photoagitation and prolonged exposure to ambient conditions, and applicability to tissue imaging mass spectrometry. This platform will be widely used as an important tool for mass spectrometry-based biochemical analyses because of its outstanding performance, long-term stability, and cost effectiveness.

Mass spectrometry assisted lithography for the patterning of cell adhesion ligands on self-assembled monolayers.

Pattern of events: A simple and flexible method has been developed for patterning cell adhesion ligands. Locally erasing self-assembled monolayers with tri(ethyleneglycol) groups on a gold substrate by using a MALDI-TOF MS nitrogen laser and filling the exposed gold surface with an alkanethiol presenting carboxylic acid groups enables subsequent immobilization of maleimide and a cell adhesion peptide, which can then recognize cells (see scheme).