Aqueous Exfoliation of Transition Metal Dichalcogenides Assisted by DNA/RNA Nucleotides: Catalytically Active and Biocompatible Nanosheets Stabilized by Acid–Base Interactions

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials & Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acsami.6b13619The exfoliation and colloidal stabilization of layered transition metal dichalcogenides (TMDs) in an aqueous medium using functional biomolecules as dispersing agents have a number of potential benefits toward the production and practical use of the corresponding two-dimensional materials, but such a strategy has so far remained underexplored. Here, we report that DNA and RNA nucleotides are highly efficient dispersants in the preparation of stable aqueous suspensions of MoS2 and other TMD nanosheets at significant concentrations (up to 5–10 mg mL–1). Unlike the case of common surfactants, for which adsorption on 2D materials is generally based on weak dispersive forces, the exceptional colloidal stability of the TMD flakes was shown to rely on the presence of relatively strong, specific interactions of Lewis acid–base type between the DNA/RNA nucleotide molecules and the flakes. Moreover, the nucleotide-stabilized MoS2 nanosheets were shown to be efficient catalysts in the reduction of nitroarenes (4-nitrophenol and 4-nitroaniline), thus constituting an attractive alternative to the use of expensive heterogeneous catalysts based on noble metals, and exhibited an electrocatalytic activity toward the hydrogen evolution reaction that was not impaired by the possible presence of nucleotide molecules adsorbed on their active sites. The biocompatibility of these materials was also demonstrated on the basis of cell proliferation and viability assays. Overall, the present work opens new vistas on the colloidal stabilization of 2D materials based on specific interactions that could be useful toward different practical applications.Financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through project MAT2015-69844-R is gratefully acknowledged. Partial funding by Plan de Ciencia, Tecnología e Innovación (PCTI) 2013-2017 del Principado de Asturias and the ERDF (project GRUPIN14-056) is also acknowledged. M.A-V. and J.M.M. are grateful to MINECO and the Spanish Ministerio de Educación, Cultura y Deporte (MECD), respectively, for their pre-doctoral contracts. O.P-V. acknowledges funding of his contract by the European Social Fund (ESF). M.C. is grateful to FCT (Fundação para a Ciência e a Tecnologia) for financial support through the post-doctoral grant SFRH/BPD/101468/2014, co-financed by national funds from the Portuguese Ministry of Education and Science and the ESF.Peer reviewe