Capillary electrochromatography immunoassay for alpha-fetoprotein based on poly(guanidinium ionic liquid) monolithic material.

Alpha-fetoprotein (AFP) is widely used as a tumor marker for the serum diagnosis of primary hepatoma. Sensitive detection of AFP level plays an important role in the early diagnosis of disease and highly reliable prediction. In this study, a novel non-competitive immunoassay (IA) based on poly(guanidinium ionic liquid) monolithic material was developed for detecting ultra trace levels of AFP in capillary electrochromatography (CEC) mode. The AFP was mixed with an excess amount of fluorescently labeled antibody. After incubation, the immunocomplex was separated from the free labeled antibody and detected by CEC coupled with laser-induced fluorescence detector. Under the optimized conditions, the developed CEC-IA performed a low detection limit of 0.05 μg L-1  (S/N = 3) and a wide linearity ranging from 0.1 to 1000 μg L-1 for AFP, which can be largely attributed to the high separation and enrichment efficiency of poly(guanidinium ionic liquid) monolithic material for the targets. The application of this method was demonstrated by determining AFP in human serum.