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

Abstract

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.