基于靶标响应DNA水凝胶的双霉菌毒素可视化检测OA

A visual sensing platform based on competitive binding mechanism between target molecules and single-stranded DNA toward aptamers,using a target-responsive DNA hydrogel as the core molecular recognition element,was developed in this study for respective detection of two mycotoxins,ochratoxin A(OTA)and aflatoxin M1(AFM1).The DNA hydrogel was constructed from linear polyacrylamide-grafted single-stranded DNA backbones(P-S1 and P-S2),which were crosslinked through hybridization with a multifunctional linker strand(Linker 1,L1)containing dual aptamer sequences specific to OTA and AFM1,forming a stable three-dimensional hydrogel network.In the presence of OTA or AFM1,specific binding between target molecules and aptamer domains in L1 reduced the crosslinking density of the DNA hydrogel,leading to hydrogel dissociation and release of pre-encapsulated gold nanoparticles(AuNPs).As a result,the supernatant underwent a visible color change from colorless to the characteristic wine-red color of AuNPs,enabling naked-eye discrimination of target presence.With increasing target concentration,enhanced hydrogel dissociation led to a higher release of AuNPs,allowing rapid quantitative detection of OTA and AFM1 based on the linear relationship between absorbance at 520 nm and target concentration.The proposed sensing platform exhibited a linear detection range of 2-20 μmol/L for OTA with a limit of detection(LOD)of 1.06 μmol/L,and 1-10 μmol/L for AFM1 with a LOD of 0.11 μmol/L.This method required neither sophisticated instrumentation nor expensive reagents,and had advantages including simple preparation,good specificity,and visual readout.Moreover,spike-and-recovery experiments in real samples demonstrated recoveries above 90%,indicating its promising potential for rapid screening of mycotoxin contamination in practical samples.