Implications of surface architecture towards the development of a rapid and label-free Glypican-3 immunosensor

Glypican-3 (GPC-3) is one of the attractive biomarkers for diagnosing hepatocellular carcinoma (HCC) because it is prominently expressed in most HCC cases. However, there is still an unsatisfactory number of non-complex analytical methods that allow for its determination. Surface plasmon resonance (SPR) immunosensors are excellent analytical platforms for sensitive, fast, and direct detection of protein biomarkers, and such a technology was applied within the framework of presented studies. Herein, we report a highly sensitive and selective method for detecting GPC-3 based on SPR. It was found that a higher sensitivity of the developed biosensor was obtained using a GPC-3 mAb-modified polyethylene glycol self-assembled monolayer (PEG SAM) surface than in the case of a GPC-3 mAb-modified carboxymethyl dextran (CMD) surface, revealing that the type of surface architecture directly impacts working parameters of SPR-based immunosensors. Studies on interaction kinetics were performed for the protein-antibody binding, enabling the calculation of kinetic and affinity constants. The antigen binding to the immobilised antibody demonstrated the equilibrium dissociation constant (K_D) of 1.87 nM, indicating a strong affinity for their biomolecular interaction. The immunosensor demonstrated high sensitivity, with a calculated limit of detection (LOD) of 0.212 nM in the case of artificial sample and 3.255 nM for diluted human serum. The SPR-based data confirmed that the immunosensor was reusable multiple times following appropriate chemical regeneration. The results of this study contribute to developing a label-free device that can be used for simple, rapid, real-time detection of cancer biomarkers.