Reversible Immuno-Infrared-Sensor for the Detection of Alzheimer´s Disease Related Biomarkers.

The development of biosensors for medical purposes is a growing field. An immuno-infrared-biosensor for the preclinical detection of Alzheimer's disease (AD) in body fluids was developed. The key element of this sensors is an ATR-crystals with chemical modified surface to catch the biomarker out of the body fluid. So far, the immuno-infrared sensor can be used only once and require time-consuming steps of sensor exchange, sensor cleaning and novel surface functionalization. Here, we developed an immuno-infrared-sensor providing a reusable surface and showcase its performance by the detection of the AD biomarker proteins A and Tau in human CSF. The sensor surface is covalently coated with the immunoglobulin binding proteins Protein A or Protein G. These were employed for non-covalent immobilization of antibodies and the subsequent immobilization and analysis of their antigens. The reversible antibody immobilization can be repeated several times with the same or different antibodies. Further, the more specific binding of the antibody via its Fc region instead of the conventional NHS coupling leads to a 3-4-fold higher antigen binding capacity of the antibody. Thus, the throughput, sensitivity and automation capacity of the immuno-infrared-biosensor are significantly increased as compared to former immuno-infrared-assays. This immuno-sensor can be used with any antibody that binds to Protein A or Protein G.