An electrochemical immunosensor comprising thionin/silver nanoparticles decorated KIT-6 for ultrasensitive detection of squamous cell carcinoma antigen

An ultrasensitive electrochemical immunosensor is designed and constructed for the quantitative detection of squamous cell carcinoma antigens (SCCAs). Silver nanoparticles (AgNPs) hybridized and 3-aminopropyltriethoxysilane functionalized graphene sheets (Ag@APTES-GS) serve as the platform to immobilize primary antibodies (Ab(1)). The mesoporous AgNPs-decorated silica KIT-6 (Ag@KIT-6) with a large specific surface area is utilized to label the electron mediator thionin (TH) and secondary antibodies (Ab(2)) by physical adsorption and chemical bonding. Carboxymethyl chitosan (CMC) doped with ionic liquids (ILs) is used to facilitate electron transfer and prevent leaking of TH resulting in multiple signal amplification. In addition to the excellent detection limit (17 fg mL(-1), S/N = 3) and wide linear range (5 x 10(-5) ng mL(-1) to 10(2) ng mL(-1)), the immunosensor shows good selectivity, reproducibility, and stability. Providing quantitative detection of SCCA in serum, the sensor has great potential in clinical and diagnostic applications.