SPR-based fiber optic biosensor for the detection of HER2

Breast cancer is currently the most prevalent cancer among women, and the level of HER2 is one of the important indicators of breast cancer prognosis. In this paper, we propose a fiber-optic biosensor based on surface plasmon resonance (SPR) for rapid and direct detection of HER2 protein using patient plasma. The method utilizes the difference in resonance wavelength shift before and after immunoassay to achieve quantitative detection of HER2 protein. To simplify the bio-modification step and improve the detection efficiency, we used protein G in a one-step reaction with 2-iminothiolane to generate a thiol functional group to form a self-assembled layer on the gold surface of the sensor. We optimized the strategy of immobilizing coating antibody on the sensor surface as well as the antibody concentration, which significantly improved the sensitivity of the biosensor to 0.20666 nm/(μg/mL), a 2.5-fold increase compared to the non-optimized case. Our protocol was able to specifically detect HER2 protein under label-free conditions with a minimum concentration of 1 μg/mL. This study provides an innovative tool and methodology for breast cancer-related research and clinical applications and is expected to promote further development in the field of breast cancer diagnosis.