Enzyme-free ECL immunesensor based on PbS nanocrystals for highly sensitive detection of alpha fetoprotein

A highly sensitive electrochemiluminescence immunosensor was originally proposed based on lead sulfide nanocrystals (PbS NCs) to detect alpha fetoprotein (AFP). Herein, PbS NCs, as a kind of nanoenzyme, was synthesized and applied to the luminol-hydrogen peroxide (L-H2O2) system for the first time. Additionally, PbS NCs with superior electrocatalytic activity toward H2O2 can enhance the electrochemiluminescence response of luminol. In this protocol, chitosan was utilized to immobilize PbS NCs through its film-forming characteristics, and further developed an ECL immunosensor by amination reaction combined with AFP antibodies. When the modified electrode was incubated with different concentrations of AFP antigen, the electrochemiluminescence intensity decreased obviously. In addition, under optimal conditions, the sensor can sensitively and selectively detect the alpha fetoprotein ranging from 1.0 × 10−5 to 800 ng/mL with the detection limit of 3.0 fg/mL. On this basis, the proposed ECL immunosensor will open up a new way to sensitively detect AFP and exhibit its application prospect in biological analysis.