1.The United Innovation of Mengchao Hepatobiliary Technology Key Laboratory of Fujian Province, Mengchao Hepatobiliary Hospital,Fujian Medical University,Fuzhou,People’s Republic of China;2.The Liver Center of Fujian Province,Fujian Medical University,Fuzhou,People’s Republic of China;3.Liver Disease Center, The First Affiliated Hospital,Fujian Medical University,Fuzhou,People’s Republic of China;4.Department of Pathology, School of Basic Medical Science,Fujian Medical University,Fuzhou,People’s Republic of China
Abstract:
The authors describe a fluorescence immunoassay for galectin-4, a candidate biomarker for various cancers. Glucose oxidase was encapsulated into a zeolitic imidazolate framework to give a composite (GOx/ZIF-8 composite) that acts as a signal-transduction tag via a biomimetic mineralization process. After modification of the composite with streptavidin, it binds biotinylated antibody against galectin-4. In the immunoassay, the response to galectin-4 results from the enzymatic oxidation of glucose. This reaction produces hydrogen peroxide (H2O2) that reacts with iron(II) ions to generate hydroxy radical (?OH), which leads to the quenching of the fluorescence of gold nanoclusters (AuNCs). Accordingly, the fluorescence quenching of AuNCs depends on the concentration of target galectin-4. The GOx/ZIF-8 composite has a high loading capacity for GOx at uncompromised enzymatic activity. The fluorescence of AuNCs is sensitively quenched by ?OH radicals. Galectin-4 can be detected by this method in concentrations as low as 10 pg·mL?1. It is expected that this kind of enzyme/MOF composite-based immunoassay has a wide scope in that it may be adapted to other low-abundance proteins and biomarkers.
Graphical abstract Schematic of a fluorescence immunoassay for galectin-4, a candidate biomarker for various cancers. It is based on a composite consisting of glucose oxidase and a metal-organic framework (GOx/ZIF-8 composite) as well as gold nanoclusters (AuNC)-iron(II) system.
