Figure 5  A range of adenosine (A) concentrations have been incubated in presence of Split-APT coated gold nanoparticles. Higher SPRi signals on Split-APT4 spots are observed upon increased concentrations allowing a detection limit of 50 nM. The injection of 1 μM of guanosine (G) does not significantly modify the SPRi signal compared to the injection of gold nanoparticles (AuNPs) alone implying a good selectivity of the biosensor.