Predicting the right spacing between protein immobilization sites on self-assembled monolayers to optimize ligand binding.

ABSTRACT

Self-assembled monolayers designed to immobilize capture antibodies are usually prepared using a mixture of functional and inactive linkers. Here, using low molar ratios (11 to 1100) of the two linkers resulted in loss of binding capability of the anti-EGFR (epidermal growth factor receptor) antibody nimotuzumab, as assessed by surface plasmon resonance imaging. We then developed a simple theoretical model to predict the optimal surface density of the functional linker, taking into account the antibody size and linker diameter. A high (11000) dilution of the functional linker yielded the best results. As an advantage, this approach does not require chemical modification of the protein.