Enhancing the sensitivity of dynamic label-free detection of low molecular weight protein

We have characterized the detection limit of Interferometric Reflectance Imaging Sensor (IRIS) with interleukin-6 (IL-6), and enhanced the sensitivity by two orders of magnitude with the following approaches. 1) The desorption rate of the surface antibodies was quantified to correct for any protein loss during the binding experiment. 2) IL-6 specific antibody was introduced to amplify the mass of IL-6 captured to the surface. In addition, we have demonstrated the ability to capture IL-6 that has already interacted with the anti-IL-6, effectively mass-tagging the cytokine, and achieve a comparable detection.