Repurposing Fc gamma receptor I (FcγRI, CD64) for site-oriented monoclonal antibody capture: A proof-of-concept study for real-time detection of tumor necrosis factor-alpha (TNF -α).

The controlled orientation of biomolecules on the sensor surface is crucial for achieving high sensitivity and accurate detection of target molecules in biosensing. FcγRI is an immune cell surface receptor for recognizing IgG-coated targets, such as opsonized pathogens or immune complexes. It plays a crucial role in T cell activation and internalization of the cargos, leading downstream signaling cascades. In this study, we repurposed the FcγRI as an analytical ligand molecule for site-oriented ADA capture, a monoclonal antibody-based biosimilar drug, on a plasmonic sensor surface and demonstrated the real-time detection of the corresponding analyte molecule, TNF-α. The study encompasses the analysis of comparative ligand behaviors on the surface, biosensor kinetics, concentration-dependent studies, and sensor specificity assays. The findings of this study suggest that FcγRI has a significant potential to serve as a universal ligand molecule for site-specific monoclonal antibody capture, and it can be used for biosensing studies, as it represents low nanomolar range affinity and excellent selectivity towards the target. However, there is still room for improvement in the surface stability and sensing response, and further studies are needed to reveal its performance on the monoclonal antibodies with various antigen binding sites and glycoforms.