Some literarture which may be of help with the reduction of non-specific binding to the sensor surface.

Becherer, T., C. Grunewald, V. Engelschalt, et al. Polyglycerol based coatings to reduce non-specific protein adsorption in sample vials and on SPR sensors. Analytica Chimica Acta 867: 47-55; (2015). Goto reference

Li, W., Q. Liu and L. Liu Antifouling Gold Surfaces Grafted with Aspartic Acid and Glutamic Acid Based Zwitterionic Polymer Brushes. Langmuir 30: 12619-12626; (2014). Goto reference

Shiyama, T., M. Furuya, A. Yamazaki, et al. Design and synthesis of novel hydrophilic spacers for the reduction of nonspecific binding proteins on affinity resins. Bioorganic & Medicinal Chemistry 12: 2831-2841; (2004). Goto reference