(Left) Schematic representing the phenomenon of coating gold with monolayer graphene for both signal enhancement and recognition element attachment. (Right) SPR angle shift after anticholera toxin (CT) injection using pure gold (red) and graphene-gold (black) surfaces functionalized with polypyrrole-NTA/Cu2+/b-CT at two different anti-CT concentrations (a, b: 4 ng·mL−1; c, d: 35 ng·mL−1). The polymer film was formed under controlled potential electrolysis (0.95 V, 1 mC·cm−2). Adapted from Singh, M.; Holzinger, M.; Tabrizian, M.; Winters, S.; Berner, N. C.; Cosnier, S.; Duesberg, G. S. J. Am. Chem. Soc. 2015, 137, 2800–2803 (ref 196). Copyright 2015 American Chemical Society.