CVD-grown MXene-CNT nanocomposite-assisted electrochemical immunosensors for label-free and ultra-sensitive monitoring of thyroid-stimulating hormone in artificial serum.

Thyroid-stimulating hormone (TSH) is a critical clinical biomarker for evaluating thyroid function and is essential in diagnosing and monitoring related hormonal disorders. However, the development of point-of-care diagnostic devices for the early detection of TSH-associated diseases remains challenging, particularly due to constraints in measurement methodologies in resource-limited settings. This research describes an effective electrochemical immunosensor developed from a novel seamless three-dimensional (3D) Ti₃C₂T_x (MXene)-carbon nanotube (CNT) nanocomposite, specifically engineered for the ultrasensitive and label-free detection of low TSH concentrations. The MXene-CNT nanocomposite was synthesized using the chemical vapor deposition (CVD) method, and its physical characteristics and electrochemical sensing capabilities were examined. The unique synergetic properties of the MXene-CNT nanocomposite enhance antibody immobilization, expand the sensor's surface area (0.119 cm²), provide additional binding sites, and improve electrical conductivity, leading to superior sensitivity and stability of the biosensor. With a label-free format, the redox mediator signal decreased significantly in response to varying concentrations of TSH, attributable to the insulating immunocomplexes formed between anti-TSH and TSH on the MXene-CNT-modified disposable electrode. The method achieved a dynamic linear range of 0.1-10 000 pg mL^-1, with a detection limit of 0.03 pg mL^-1, showcasing high selectivity against interferents. Importantly, this study presents the first successful electrochemical detection of TSH in artificial serum using the CVD-grown MXene-CNT nanocomposite immunosensor, underscoring its potential for real-sample analysis in complex biological environments. The current study opens new avenues for leveraging the CVD-grown MXene-CNT nanocomposites in designing and developing molecular diagnosis-based electrochemical and related biosensors.