Tetrazine Functionalized Graphene Enables Capture of Ultra-Low Concentrations of Biomacromolecules

Monolayer graphene has great potential for a range of technological and biomedical applications. To achieve this potential, however, selective functionalization of the surface using mild chemical methods that yield spatially and chemically well-defined functional groups is needed. Here, we describe a method to densely and uniformly modify the surface of graphene using a diazonium salt containing a tetrazine moiety, a functional group amenable to bioorthogonal chemistry. The resulting functionalized graphene efficiently undergoes inverse electron demand Diels-Alder reactions with trans-cyclooctene (TCO) coupled compounds, including a small organic molecule and an anti-GFP nanobody. The nanobody decorated graphene readily captures EGFP tagged apoferritin (EGFP apo-Ftn) and by following the binding by total internal fluorescence microscopy, we demonstrate that the functionalized graphene can robustly capture EGFP apo-Ftn molecules at a concentration of 2 pm.