Biosensor Based on Aptamer Cross-Linked Hydrogel with Fluorescence “Turn-on” Properties for One-Step Detection of Zearalenone

To develop an aptamer-crosslinked fluorescent hydrogel biosensor for the detection of zearalenone (ZEN) in foods.

Primer strand A and strand B modified with Black Hole Quencher 1 (BHQ1) were copolymerized under specific conditions to form polymer A (PS-A) and polymer B (BHQ1-PS-B), respectively. Aptamer labeled with 6-carboxyfluorescein (FAM-Apt), serving as both a signal probe and crosslinker, hybridized with PS-A and BHQ1-PS-B via complementary base pairing to form a DNA hydrogel. ZEN competed with BHQ1-PS-B for binding to FAM-Apt, leading to hydrogel dissociation. This resulted in the separation of the fluorophore (FAM) and the quencher (BHQ1), turning on the fluorescence signal.

This method enabled one-step qualitative and quantitative analysis of ZEN, with a linear range of 1-500 nmol/L and a detection limit of 8.7 nmol/L. Recovery rates for spiked flour samples ranged from 80.3% to 94.2%.

The aptamer-crosslinked fluorescent hydrogel biosensor is sensitive, efficient, time-saving, and thus suitable for the rapid detection of ZEN in foods.