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.

Highly dispersible graphene oxide (GO) sheets of uniform submicrometer size were successfully fabricated from pristine graphite using a simple mechanochemical process. The GO flake morphology was transformed into a spherical form, and the density was decreased slightly via the ball-milling process. Ball-milled GO can be used as an electrorheological (ER) material because of its small particle size, low conductivity, and outstanding dispersibility in silicone oil. We found that the 2-h ball-milled GO-based ER fluid had the best ER performance (shear stress of 78.5 Pa and 630% ER efficiency), which was double that of the nonmilled GO-based ER fluid. The response time to form a fibrillar structure along the applied electric field direction and the recovery time to the starting level decreased with increasing ball-milling time. Additionally, the retarded settling velocity of isolated GO sheets and the electrostatic repulsion between oxygen functional groups on the GO sheets combined to improve the antisedimentation property. The ability to control the size of graphene sheets is a great opportunity to advance graphene commercialization in a high-quality, scalable production setting.

The graphene oxide-coated iron oxide/silica core/shell nanoparticles (Fe3O4/SiO2/GO NPs) are successfully fabricated and adopted as the dual stimuli-responsive smart fluid. The Fe3O4/SiO2/GO NPs exhibit both electrorheological (ER) and magnetorheological (MR) characteristics, attributed to the SiO2/GO layer in the shell part and Fe3O4 in the core part, respectively. Particularly, the ER efficiency of the Fe3O4/SiO2/GO NPs-based ER fluid is ca. 191 at the applied electric field of 3 kV mm–1. Moreover, the MR performance of the Fe3O4/SiO2/GO NPs-based MR fluid is significantly enhanced up to 135-fold at the applied magnetic field of 1 T compared to the zero-field stress. Furthermore, it is remarkable that the Fe3O4/SiO2/GO NPs represent high colloidal stability and outstanding antisettling property because of the electrostatic repulsion between oxygen functional groups on GO nanosheets and the relatively low density compared with other magnetic particles. Dual stimuli-responsive characteristics in addition to the excellent antisedimentation property of the Fe3O4/SiO2/GO NPs-based smart fluid would provide a feasible candidate for practical applications.

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Silicon thin films that fulfil the needs of current semiconductor lithography were prepared from a new class of polycyclosilane–polysiloxane hybrid materials.