A biosupramolecular approach to graphene: Complementary nucleotide-nucleobase combinations as enhanced stabilizers towards aqueous-phase exfoliation and functional graphene-nucleotide hydrogels

The ability to use RNA/DNA nucleotides as colloidal stabilizers for graphene would be an important asset, as a close graphene-nucleotide association would facilitate access to hybrid systems where the rich covalent and supramolecular chemistry of these biomolecules could be exploited alongside graphene in a number of applications. Unfortunately, single RNA/DNA nucleotides are inefficient graphene dispersants. Here we propose and demonstrate a supramolecular strategy which overcomes this limitation, affording aqueous dispersions of high quality graphene flakes with much improved colloidal stability. A nucleotide is combined with its complementary nucleobase yielding stable hydrogen-bonded supramolecular entities that adsorb more strongly on the graphene surface than their individual components. Based on this approach, graphene-nucleotide hybrid hydrogels could be readily obtained, where the graphene flakes were intimately and uniformly intermixed with the nucleotide-based gel phase. Such hydrogels exhibited higher uptakes and/or slower release profiles of dyes and drugs (rhodamine B, methylene blue and tetracycline) than their graphene-free counterparts. Cell proliferation tests suggested the graphene materials obtained with nucleotide-nucleobase stabilizers to be biocompatible. The present results constitute a novel strategy in the processing and molecular integration of graphene that could be extended to other (bio)molecules of interest towards the realization of functional materials for different applications.