Aptamer HB5 modified terahertz metasurface biosensor used for specific detection of HER2

In the work, an aptamer modified terahertz (THz) metasurface (MS) biosensor is proposed to specifically detect the human epidermal growth factor receptor 2 (HER2) which is a typical label of breast cancer. The biosensor is an array structure consisting of two metal split-ring-resonators (SRRs) in a unit cell. Compared with the conventional SRRs directly fabricated on high resistance silicon substrate, 500-nm-thick silicon dioxide spacer is introduced between the metal SRRs and the silicon substrate of the proposed biosensor to obtain high Quality (Q). Simulation results show that the biosensor has two resonant frequencies, and the sensitivity of the high frequency resonant frequency reaches to 108 GHz/RIU (Refractive Index Unit). The biosensor is fabricated by using a surface micromachining process and characterized by a THz time domain spectroscopy (TDS) system. To specifically detect the HER2, the aptamer-HB5 (APT-HB5) with a concentration of 5 μmol/mL is used to modify the surface of the biosensor. The experiment result show that the aptamer modified biosensor has higher detection sensitivity, and the limit-of-detection (LOD) reaches to 0.1 ng/mL. Most importantly, it is more sensitive to the antigen HER2 than the other markers of the CEA and the AFP. The proposed method can be extended to design other aptamer biosensors for specifically detecting the biomarkers of other cancers. This study paves a new way for specific detection of cancer biomarkers and other biomolecules, which is of great significance for early detection of cancer, especially for the breast cancer.