Covalent immobilization of proteins for the biosensor based on imaging ellipsometry.

In the development of biosensors, the immobilization of biomolecules at interfaces played a crucial role. The feasibility of using 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (Glu) to modify silicon surface to immobilize covalently protein for immunoassay with the biosensor based on imaging ellipsometry was investigated. The higher density and stability of human IgG layer could be obtained on the silicon surface modified with APTES and Glu than that on the silicon surface modified with dichlorodimethylsilane (DDS). The human IgG molecules immobilized covalently on APTES-Glu surface bound more anti-IgG molecules than that on DDS surface, which indicated that the human IgG molecules could maintain higher binding capability on APTES-Glu surface. Tween 20 was able to block the undesirable adsorption on APTES-Glu surface, and also enhanced the recognition between human IgG and its antibody on both APTES-Glu and DDS surfaces. The combination of this protein covalent immobilization and the biosensor has the potential to be developed into a fast, simple immunoassay technique.