LSPR-enhanced terahertz metasensors for highly sensitive CRP detection via antibody functionalizations

C-reactive protein (CRP) is a biomarker that significantly elevates in cancer patients. Its detection with high sensitivity and specificity is of paramount importance for the early diagnosis and screening of cancer. In this study, we proposed and experimentally demonstrated a CRP antibody-functionalized metasurface biosensor with a simplified metallic design, enabling high-sensitivity detection of CRP using terahertz time-domain spectroscopy. Colloidal gold nanoparticles enhance the sensitivity and quantitative detection capabilities of the biosensor by leveraging the local surface plasmon resonance (LSPR) effect and the enhanced biomolecular recognition. Moreover, the addition of a high concentration of CRP antibodies improves the antigen capture efficiency, thereby further boosting the sensor's performance. In this study, the designed biosensor was used to measure varying concentrations of CRP and two different types of antigens. By analyzing the sensor's response variations under different antigen-binding conditions, the specificity of its CRP recognition was validated. Experimental results demonstrated that the sensor exhibited a limit of detection as low as 100 pg/mL, with robust discriminatory capacity between target antigens and nonspecific molecular interference, ensuring exceptional selectivity in detection. This result further confirms the exceptional performance of the metasurface biosensor in precise biomolecular detection, providing crucial technological support for achieving efficient and accurate early cancer screening.