Novel carbon paper-based solid-state nanochannels integrated with click chemistry for sensitive detection of thyroid stimulating hormone.

Novel solid-state nanochannels (SSNs) are formed employing Toray carbon paper as the substrate prior to the APTES-norbornene sol-gel coating. Using thyroid stimulating hormone (TSH) as a model target, high-affinity aptamers are selected and split into two parts, with one end of a segment modified with tetrazine molecules. After binding to TSH, the two aptamer segments form a ternary complex, which is then captured via classic click chemistry between norbornene and tetrazine, enabling quantitative detection through monitoring and analyzing steady-state current changes. Comprehensive characterization via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), and Fourier transform infrared spectroscopy (FTIR) confirms the successful modification of APTES-norbornene and the occurrence of the click reaction. A linear calibration curve is constructed for TSH in the range of 0.3-600 pg mL-1. Compared to ELISA-based TSH detection kits, the novel technology improves the limit of quantification (LOQ) 100-fold. Serum TSH levels in five differentiated thyroid carcinoma patients are detected, yielding results consistent with standard assays. This work expands the application of commercialized carbon paper in the life and health field by developing a rapid and ultrasensitive TSH detection assay.