Figure 1. The hC3Nb1 nanobody does not interact with native complement C3, but does interact with protease activated complement C3b. To analyze the interaction between hC3Nb1 and the control nanobody hC3Nb2 (4) with C3 or C3b, nanobody at 10 μg/mL was immobilized on anti-penta his (His1K) biosensors (Sartorius). The sensors were transferred into 50 nM C3 (left) or C3b (right) for 180 seconds, followed by a 180 seconds dissociation period. The sensorgrams were normalized by subtracting sensorgrams recorded without C3 and C3b.