Ultrasensitive Quantification of Thyroid-Stimulating Hormone and Thyroxine by Nanoelectronic SnS₂ Transistor Sensors

The measurement of thyroid hormones in serum is widely regarded as the most valuable single laboratory tool for assessing thyroid function. This study presents a highly sensitive tin disulfide nanosheet-fabricated field-effect transistor (SnS₂-FET) designed for the detections of human thyroid-stimulating hormone (hTSH) and thyroxine (T4). By co-modifying an antibody (Ab_TSH for detecting hTSH), or a DNA aptamer (Apt_T4 for detecting T4), with polyethylene glycol (PEG) on the SnS₂-FET channel surface, the PEG:Ab_TSH/SnS₂-FET and PEG:Apt_T4/SnS₂-FET devices achieve highly sensitive and selective detections of hTSH and T4, respectively, even in a high ionic strength buffer (1× PBS) or undiluted serum. With a low limit of detection (in the femtomolar level) and a wide linear working range (spanning at least 6 orders of magnitude of analyte concentration), the PEG:Ab_TSH/SnS₂-FET immunosensor and PEG:Apt_T4/SnS₂-FET aptasensor can detect the hTSH and T4 levels encountered in the spectrum of thyroid disorders. Notably, these specific receptor-modified SnS₂-FET devices display negligible cross-reactivity with other pituitary hormones or serum components. This research indicates that the nanoelectronic SnS₂-FET sensor platforms hold significant potential for point-of-care clinical diagnostics, particularly for the ultrasensitive detection and early screening of medical conditions.