A disposable ultrasensitive immunosensor based on MXene/NH₂-CNT modified screen-printed electrode for the detection...

Cancer antigen 125 (CA125) is the gold standard biomarker for clinical diagnosis of ovarian cancer, with a threshold value of 35 U/mL in serum. In this paper, a disposable ultrasensitive immunosensor based on Ti₃C₂T_x-MXene/amino-functionalized carbon nanotube (NH₂-CNT) modified screen-printed carbon electrode (SPCE) was constructed for the detection of the ovarian cancer antigen CA125. By optimizing the mass ratio of Ti₃C₂T_x to NH₂-CNT, Ti₃C₂T_x/NH₂-CNT composite with excellent electrochemical properties was prepared, which is beneficial for amplifying the initial electrochemical signal. The positively charged NH₂-CNT effectively alleviated the stacking problem of Ti₃C₂T_x, and its amino group also facilitated the covalent immobilization of the capture antibody. Meanwhile, chitosan (CS) with excellent film-forming ability was also used to successfully enhance the adsorption of electrode material, thus improving the stability of the sensor. In addition, CS could further enhance the current signal. The prepared immunosensor exhibited excellent performance in CA125 detection with a wide linear range from 1 mU/mL to 500 U/mL, and good selectivity, reproducibility and lomg-term stability. Furthermore, the immunosensor showed satisfactory results for the detection of CA125 in clinical serum samples, which is promising for the clinical screening, early diagnosis and prognostic examination of ovarian cancer.