Silicon and hydrogenated amorphous silicon carbide as biofunctional platforms for immunosensors

In this work, we evaluate the performance of two biofunctionalization processes on silicon and hydrogenated amorphous silicon carbide (a-SiC:H). The biofunctionalization processes were designed to immobilize antibodies via non-specific physical adsorption or covalent attachment. The impact of the two surface types (crystalline and amorphous) on the resulting immunosensing layer is discussed in terms of the possible orientation, stability, and bioactivity of the immobilized antibodies. To evaluate the formation of active groups on the surface before and after the immobilization process, we used Fourier-transform infrared (FTIR) spectroscopy. On the other hand, to visualize the topography changes on the different surfaces with immobilized antibodies, we used atomic force microscopy (AFM). ELISA assay was conducted to obtain a quantitative parameter associated with the density of immobilized antibodies on the platforms. The results showed that the antibodies were immobilized on both platforms by any of the two immobilization mechanisms. The antigen capture did not show a direct relationship with the antibody estimation made by ELISA. According to the results, the a-SiC:H platforms by covalent attachment achieved the highest density of immobilized antibodies compared to silicon. However, its performance in the antigen detection assay was lower compared to silicon platforms. We concluded that the performance of the silicon platform was better in terms of its biofunctionalization and antigen detection. The orientation and structural integrity of the antibodies on the platforms was crucial to its performance on antigen detection.