A "turn-on" FRET aptasensor based on the metal-organic framework-derived porous carbon and silver nanoclusters for zearalenone determination

Abstract

Zearalenone (ZEN) is a fungal secondary metabolite with an estrogen-like structure. Its widespread existence and potential hazards to human and animal health call for alternative rapid determination methods to monitor ZEN in food and the environment. Herein, a robust and enzyme-free "turn-on" aptasensor based on fluorescence resonance energy transfer (FRET) was developed for the sensitive identification of ZEN. Aptamer-modified silver nanoclusters (AgNCs) and porous Fe3O4/carbon octahedra derived from the metal-organic framework (MOF) acted as the FRET energy donor−acceptor pair in fluorescence quenching. DNA-templated AgNCs can be adsorbed onto the surface of porous Fe3O4/carbon octahedra through π-π stacking, which will lead to the FL quenching of AgNCs. However, in the presence of the ZEN, the formation of the ZEN/aptamer complex promoted the release of AgNCs and thereby brought about the recovery of fluorescence, which can be used to indicate the concentration of ZEN. The prepared aptasensor was characterized by various physicochemical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), energy-dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS) and circular dichroism spectroscopy (CD). By combining the excellent quenching properties and easy separation of magnetic porous Fe3O4/carbon octahedra, as well as the appealing photostability and water solubility of AgNCs, the proposed FRET platform demonstrated superior analytical performance with a linear range of 0.01–250 ng mL−1 and a LOD as low as 2 × 10−3 ng mL−1. Most importantly, the practicability and reliability of the FRET-based strategy were confirmed by conducting the determination of ZEN in real samples.