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Two-dimensional 2H-phase MoS2 nanosheets can be used as a non-noble metal-based catalyst for nitroarene and organic dye reduction, thus being of potential utility towards the treatment of industrial wastewater. However, their activity is severely limited by the inertness of their pristine basal surface. We report here a simple approach for the catalytic activation of solvent-dispersed MoS2 nanosheets based on the introduction of sulfur vacancies by hydrazine treatment. MoS2 nanosheets boasting markedly improved catalytic activities in the reduction of 4-nitrophenol, 4-nitroaniline, methyl orange and methylene blue by NaBH4 could be obtained, outperforming many prior non-noble metal-based catalysts developed for such reactions. Notably, the improvement in catalytic activity was not compromised by the use of a proper dispersant to colloidally stabilize the activated nanosheets in the aqueous reaction medium. Substrate-supported catalysts could be prepared by immobilizing the nanosheets on melamine foam, facilitating their handling and reutilization. The chemical processes taking place between the investigated reagents and the MoS2 catalyst were also discussed and rationalized, based on which a mechanism for nitroarene/dye reduction mediated by the sulfur vacancies was proposed.

This work reports on the fabrication and performance of a simple amperometric immunosensor device to be potentially used for the detection of serum anti-citrullinated peptide antibodies (ACPAs), which are specific for rheumatoid arthritis (RA) autoimmune disease. Sera of RA patients contain antibodies to different citrullinated peptides and proteins such as fibrin or filaggrin. Herein, a chimeric fibrin–filaggrin synthetic peptide (CFFCP1) was used as a recognition element anchored to the surface of a multiwalled carbon nanotube–polystyrene (MWCNT–PS) based electrochemical transducer. The transducer fabrication process is described in detail together with its successful electrochemical performance in terms of repeatability and reproducibility of the corresponding amperometric response. The resulting immunosensor approach was initially tested in sera of rabbits previously inoculated with the synthetic peptide and eventually applied to the detection of ACPAs in human sera. A comparative study was carried out using control serum from a blood donor, which demonstrated the selectivity of the immunosensor response and its sensitivity for the detection of anti-CFFCP1 antibodies present in RA patients., Peer Reviewed, Postprint (published version)