Highly sensitive and selective detection of the pancreatic cancer biomarker CA 19-9 with the electrolyte-gated MoS 2 -based field-effect transistor immunosensor

Background: Since the evaluation of CA 19-9 antigen level in human serum is crucial for the early diagnosis of a vast range of diseases, especially pancreatic cancer, it is important to apply a simple, rapid and sensitive detection method. We employed an electrolyte-gated field-effect transistor with MoS2 nanosheets channel as an immunosensor for recognition of CA 19-9 tumor marker. Method: To obtain MoS2nanosheets, the liquid-phase exfoliation method was carried out by dispersing MoS2 crystals in N, N-dimethylformamide. After that, the dispersed MoS2 nanosheets were dropped onto the region between the source and drain electrodes to create a semiconducting channel of MoS2. Later, the MoS2 channel surface was modified by employing 1-naphthylamine (NA) and glutaraldehyde (GA) for covalent immobilization of antibody 19-9 on the surface of the MoS2 nanosheets. The decreasing of source- drain current of the proposed FET in the presence of CA 19-9 antigen concentration measured. Results: : Electrical measurements revealed the depletion mode n-type behavior of MoS2nanosheets with the FET mobility of 0.02 cm2 V-1 s-1, current on/off ratio of 883.96, and the subthreshold swing of 795.54 mV/decade. Due to the n-type behavior of the MoS2-based FET immunosensor, increasing the concentration of the CA 19-9 antigen from 1.0×10-12 U/ml to 1.0×10-4U/ml resulted in the decrease of the source-drain currents. Compared to other techniques, using MoS2-based FET immunosensor for CA 19-9 antigen detection exhibited a lower detection limit of 2.8×10-13 U/ml and a wide linear range. The designed MoS2-based FET immunosensor, owning a great selectivity, was operated precisely for trace amounts of real human serum samples. Conclusions: : Possessing vast beneficial properties makes the MoS2-based FET immunosensor a marvelous alternative for detecting even the lowest concentration of CA 19-9 antigen in human serum samples in the early stages of pancreatic cancer, to improve the chance of curing the disease.