Abstract
Graphene offers tremendous potential for applications in biomedical and pharmaceutical areas, ranging from molecular diagnostics, biosensors, and prosthetics to implants and drug delivery. However, realising the full potential of graphene is blocked by a limited understanding of the nature and detail of its noncovalent interactions with biological molecules in aqueous dispersion, where such applications can be used. Here, we studied the adsorption of amino acids and peptide on graphene in water utilising Nuclear Magnetic Resonance spectroscopy by observing 1H signals of individual biomolecules when exposed to graphene. The peptide-graphene interactions appeared to be driven by the binding affinity of individual amino acids, when aromatic residues contributed most to the peptide binding to graphene, thus emphasising the predominance of π−π interactions over other forces. The strength of the interaction between some amino acid residues and graphene followed the order: Tryptophan (Trp) > Histidine (His) > Cysteine (Cys) ≈Arginine (Arg). Such strong yet reversible interactions of biomolecules with the graphene monolayer in water could be critical to control their selective binding to and release from the graphene surface, which is a prerequisite for many applications. (e.g., for molecular imaging and/or drug delivery across biological membrane barriers).