Figure 3.

Real-time shifts in resonance wavelength from representative microrings upon covalent immobilization of anti-(human thrombin) antibody onto the sensor surfaces at three different pHs and in the presence (a) and absence (b) of 100 mM aniline. In each trace the sensors were initially incubated in buffer (with or without aniline, respectively) at a flow rate of 30 μL/min and a 5 μg/mL solution of 4FB-modified antibody with or without 100 mM aniline was flowed for 30 min. After switching back to the original buffer for 20 minutes, non-covalently attached antibody was removed with a low pH (pH 2.2) glycine buffer rinse. The sensors were then returned to the respective buffer at t = 57 min to determine the residual net shift corresponding to the amount of covalently immobilized antibody.