Site-specific covalent attachment of an engineered Z-domain onto a solid matrix: An efficient platform for 3D IgG immobilization

• An efficient platform for 3D IgG immobilization is proposed.
• The platform is based on the site-specific covalent attachment of Z-Cys onto solid.
• The Z-Cys is immobilized in a site-specific, oriented, and irreversible attachment manner.
• The IgG-binding characteristic of the immobilized Z-Cys was investigated using HPLC.
• The proposed approach may be extended to other biochip or biosensor applications.

Immobilized antibodies with oriented and homogeneous patterns are crucial to solid-phase molecular recognition assay. Antibody binding protein-based immobilization can effectively present the desired antibodies. However, steadily installing the stromatoid protein with site-specific attachment manner onto a matrix surface remains to be elucidated. In this study, we present an optimal protocol to tightly attach an immunoglobulin G (IgG)-binding protein (Z-domain) through covalent incorporation of Cys-tag and maleimide group onto polystyrene surface to guarantee site-specific, oriented, and irreversible attachment, resulting in a highly efficient platform for three-dimensional IgG immobilization. The actual IgG-binding characteristic of immobilized Z-Cys was investigated by employing affinity chromatography and size exclusion chromatography. And the efficacy and potential of this platform was demonstrated by applying it to the analysis of interaction between rabbit anti-HRP IgG and its binding partner HRP. The proposed approach may be an attractive strategy to construct high performance antibody arrays and biosensors given that the antibody is compatible with the Z-domain.

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