羟基自由基响应聚集的磁弛豫开关传感器检测伏马毒素B1OA

To address the issues of complex matrix interference and false positives in the quantitative detection of fumonisin B1(FB1),a novel magnetic relaxation switch(MRSw)sensor based on ultra-small gadolinium oxide(Gd2O3)nanoprobes and their hydroxyl radical(·OH)-responsive aggregation was developed for highly sensitive and specific detection of FB1 in food matrices.Hydrophobic Gd2O3-OA nanoparticles with an average particle size of approximately 1.30 nm were synthesized by high-temperature pyrolysis and then phase-transferred with an amphiphilic ligand(Dodecenyl succinic anhydride-tyramine conjugate,DDSA-Ty)to obtain hydrophilic Gd2O3-Ty paramagnetic nanoprobes functionalized with tyramine.In the competitive immunoassay system constructed on the surface of magnetic beads,the target FB1 regulated the capture amount of horseradish peroxidase(In the form of enzyme-labeled secondary antibody,HRP-Ab2).After magnetic separation,the enzyme(HRP-Ab2)in the supernatant catalyzed the in-situ generation of·OH from hydrogen peroxide,which activated the tyramine phenolic hydroxyl groups on the probe surface and induced rapid specific covalent aggregation of the nanoprobes,significantly shortening the transverse relaxation time(T2)of the surrounding water protons.Under optimized conditions,ΔT2 exhibited a good linear relationship with FB1 concentration in the range of 10‒1000 ng/mL(r=0.992),with a limit of detection(LOD)as low as 3.04 ng/mL.This method showed no significant cross-reaction toward commonly coexisting mycotoxins such as aflatoxin B1 and ochratoxin A.The proposed method was applied to detection of actual wheat flour and corn flour samples,yielding spiked recoveries ranging from 91.0%to 103.1%,with relative standard deviation(RSD)≤6.9%,and the detection results were consistent with those of the enzyme-linked immunosorbent assay(ELISA).This Gd-MRSw sensor had strong resistance to matrix interference,and was easy to operate,providing a new strategy for accurate quantitative detection of mycotoxins in complex food samples and holding substantial potential for practical applications.