Colorimetric aptasensor for fumonisin B1 detection based on the DNA tetrahedra-functionalized magnetic beads and DNA hydrogel-coated bimetallic MOFzyme

The toxicity and incidence of fumonisin B1 (FB1) pose a major challenge to public health and the environment, prompting the development of alternative quantitative strategies for FB1. Herein, a colorimetric aptasensor was constructed based on DNA tetrahedra-functionalized magnetic beads (MBs) and DNA hydrogel-coated Mn-Zr bimetallic metal-organic frameworks-based nanozyme (MOFzyme). Initially, MBs functionalized by DNA tetrahedra demonstrated excellent capturing capability for FB1. Along with the capture of FB1, catalyst DNA (C) was released into the supernatant. Aided by fuel DNA (F), C can trigger continuous cleavage of the main chains and cross-linking points of the DNA hydrogel through an entropy-driven DNA circuit integrated into the hydrogel coating. Subsequently, the bimetallic MOFzyme encapsulated inside the DNA hydrogel was exposed and exerted its superb peroxidase-like activity, producing a colorimetric signal whose intensity was positively dependent on the amount of FB1. The developed aptasensor exhibited good linearity in the range of 5 × 10-4 to 50 ng mL-1 with a limit of detection (LOD) of 0.38 pg mL-1, and reasonable specificity in different matrices. Furthermore, the aptasensor was successfully applied to quantify FB1 in actual samples with recoveries fell within 92.25 %− 108.00 %, showing its great potential in environmental monitoring and food safety.