The specificity of the HCR for the target sequence was assessed by performing different experiments. First, a non-complementary target (Target 2, see Table SD1) was injected: no signal change was recorded (Fig. 3). The following injection of Hairpin1_Giardia/ Hairpin2_Giardia mix (NC targetþHCR) determines only a slight non-specific signal, suggesting that, as expected, no reaction occurs on the surface in the absence of the specific target sequence. In a second control experiment, Hairpin2_Giardia was injected on the specific target-probe complex, recording no signal change. This was expected as Hairpin2_Giardia should only hybridize
to the bound Hairpin1_Giardia (Fig. 3). Subsequent injection of Hairpin1_Giardia (Target_GiardiaþH2þH1 in Fig. 3) increases the signal analogously to the injection of Hairpin1_Giardia on the pristine target-probe complex.