Objective   To design a new immunosensor for the detection of α-fetoprotein (AFP) antigen based on multi-wall carbon nanotube-chitosan-Thionine (MWCNT-CS-THi) nanocomposite with  cysteine hydrochloride (CH) and gold nanoparticles (GNPs) modified glassy carbon electrode (GCE).    Methods   Firstly

MWCNT-CS-THi composite was dropped onto the surface of the GCE. Subsequently

GNPs were adsorbed onto the nanocomposites surface through positive charge of thionine and chitosan for immobilizing CH. Finally

glutaraldehyde (GA) cross-linking method was employed to immobilize AFP antibodies on the electrode surface. Thus

the finished immunosensor was constructed. The experimental condition was optimized through changing pH of the system and incubation time. The stability

specificity and repetitiveness of the system were evaluated.    Results   The optimal pH value was 6.5

and incubation time was 20 min. Under optimal conditions

the proposed immunosensor displayed a broader linear response to AFP

with a working range from 0.1 to 200.0 ng/ml and a detection limit of 0.07 ng/ml. Sound stability

specificity and repetitiveness were obtained in our immunosensor for AFP detection.    Conclusion   Our self-made immunosensor is easy to produce

and has high sensitivity

wide detection range and low detection limit.