Sensing of hemin binding to albumin using Gebased plasmonic antennas operating in the THz range

Albumin-based biofunctionalized biosensors have the potential to be utilized for the detection of physiological ligands (e.g., heme) and of pathogenic proteins. In human cells, heme is always bound to proteins due to its toxic nature. However, free heme can be present within tissue and in the bloodstream as a consequence of hemolysis or under pathological conditions like malaria or sickle cell anemia. Therefore, the development of an albumin-based heme biosensor could be relevant from a biomedical viewpoint. In this study, we developed a protein-sensing platform by immobilizing albumin on CMOS-compatible Ge-based THz plasmonic antennas via drop-cast biofunctionalization. To set up the biosensor, the sensing platform was used to quantitatively measure the binding of hemin, a well-known physiological ligand of albumin. This measurement was performed using THz time-domain spectroscopy in dichroic transmission mode, achieving a sensitivity of approximately ~ 200 GHz/mM of the HSA:hemin complex. These preliminary results support the use of CMOScompatible Ge-based THz plasmonic antennas as innovative sensors that could be monolithically integrated with conventional electronics for storage, processing, and communication into an all-in-one system.