Several control experiments were then performed. First, HCR was carried out stepwise on the surface: after the injection of the target sequence Target_Giardia, an injection of Hairpin1_Giardia was performed (TargetþH1, in Fig. 3). After this step, a signal increase is visible, although lower than what observed after Target_Giardia injection in the first step. A further signal increase of similar magnitude is produced after the subsequent injection of
Hairpin2_Giardia (TargetþH1þH2). This data validate the molecular mechanism underlying the HCR on the sensor surface