Figure 2From: Graphene oxide-based SPR biosensor chip for immunoassay applicationsGOS, terminal groups, and carboxyl groups. (a) Molecular structure of GOS. (b) Modification of terminal groups (-COOH) of monolayers of GOS film by surface-confined ester reactions. (c) Carboxyl groups ending in -COOH cause GOS surface to exhibit affinity for NH2 end of protein.Back to article page