Antibody-invertase Cross-linkage Nanoparticles: A New Signal Tag for Point-of-Care Immunoassay of Alpha-fetoprotein for Hepatocellular Carcinoma with Personal Glucometer

Methods based on immunoassays have been developed for cancer biomarker alpha-fetoprotein (AFP), but most involve complicated or stripping procedures and are unfavourable for routine use. Herein we report the proof-of-concept of simple and point-of-care (POC) immunoassay for AFP in hepatocellular carcinoma on a portable personal glucometer (PGM) by using antibody-invertase cross-linkage nanoparticles as the signal-generation tags. Antibody-invertase cross-linkage nano tags were synthesized by using reverse micellar method with glutaraldehyde. The POC immunoassay was carried out on monoclonal anti-AFP capture antibody-coated microplate with a sandwich-type reaction mode. Introduction of invertase nano labels accompanying target AFP could hydrolyse sucrose into glucose and fructose. The produced glucose molecules could be determined on a portable personal glucometer. Relative to unimolecular invertase labelling, improved analytical features were acquired with antibody-invertase nano labelling. With the nano labels, PGM-based immunoassay exhibited good electrochemical responses for the detection of AFP, and allowed detection of AFP at a concentration as low as 5.4 pg mL −1 . Moreover, a good repeatability and intermediate precision could be found down to 12.68 %. Good well-matched results were obtained for analysis of human serum specimens between POC immunoassay and commercial human AFP ELISA kit.