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Creative Diagnostics offers an extensive range of custom services for silicon surface modification and oriented antibody immobilization. Our experienced scientists can optimize the immobilization to ensure the homogeneity of antibody adsorption layer on surfaces for highly sensitive assays.
Silicon is the most commonly used material as substrate in electronic devices in biosensor. The immobilization of antibodies and the retention of their conformations on the silicon surface are prerequisite for the development of biosensor. Although antibodies can be simply immobilized on silicon surface by physical adsorption, their biological activities will be compromised. Based on our years of experiences on antibody immobilization, Creative Diagnostics are proficient in oriented antibody immobilization on silicon surface to optimize your biosensor.
Organic Modification of Silicon Surface
Silanization chemistry is applied for organic modification of silicon surface, i.e., the reaction between hydroxyl terminated surfaces and organosilanes. 3-Aminopropyltriethoxysilane (APTES) is the most frequently used silane based agent, enabling the subsequent immobilization of carboxylic acid of antibodies. More often, further derivatization with glutaraldehyde can be applied to chemically bind amine groups within the antibodies. Of note, free sulfhydryl groups generated during the production of antibody Fab fragments can react with appropriate modified silicon surface.
Figure 1. Schematic representation of a silicon nanowire-based device (top left). The nanowire is chemically modified (step 1), followed by the immobilization of antibodies (step 2) and the binding of an analyte (step 3). S and D stand for source and drain, respectively.
Oriented Immobilization with Protein A and G
Protein A and G are antibody-binding proteins which have a high affinity for the Fc region of some antibodies, especially IgG. Antibody can be adsorbed to protein A or G immobilized on silicon surface. This mode of immobilization results in the uniform orientation of the antigen-binding sites in Fab fragment, and maximizes the antigen-binding capability of the antibody. In addition, the protein A and G can serve as a spacer arm for the immobilized antibody, which prevent antibody attach to surface directly and facilitate antibody-antigen interaction.
Creative Diagnostics offers high quality custom services for silicon surface modification and antibody immobilization. Our wealth of knowledge allows us to immobilize antibodies to silicon surface efficiently and reproducibly, without compromising the functionality of the attached antibodies.