Fig. 1
Reversible functionalization via competitive supramolecular complexation. a, b Surface plasmon resonance imaging (SPRi) was used to monitor the (single) reversible functionalization of a biotinylated 2D substrate through supramolecular complexation of multivalent (i.e., with multiple binding pockets) (neutr)avidin and desthiobiotinylated antibody. c The multivalent nature of neutravidin was confirmed using spectrophotometric absorption analysis of 4′-hydroxyazobenzene-2-carboxylic acid bound to neutravidin (HABA-NAV; λ = 500 nm), which was displaced by biotin resulting in unbound (i.e., free) HABA (λ = 350 nm). b, d–f Following a cascade binding strategy, neutravidin, desthiobiotinylated antibody against bone morphogenetic protein 7 (D-@BMP7), and BMP7 were sequentially complexed onto the biotinylated SPRi substrate. g Based on a difference in binding affinity, h supramolecular displacement of D-@BMP7 by biotin was achieved, resulting in the release of the antibody/antigen complex. The insets show the averaged response curves of a specific analyte injection versus a non-specific analyte (i.e., BSA) injection. All magenta data indicate (neutr)avidin. All blue/white dashed data indicate D-@BMP7. All yellow data indicate BMP7. All blue solid data indicate biotin. All light-colored data indicate ± standard deviation (n = 6). All error bars indicate ± standard deviation (n = 6)
