Electrochemical aptasensor for aflatoxin B1 detection using cerium dioxide nanoparticle supported on iron-porphyrinic metal–organic framework as signal probes

A novel electrochemical aptasensor was fabricated by using cerium oxide (CeO2) nanoparticle loaded spindle iron-porphyrinic metal–organic framework (PorMOF) as signal probe to detect aflatoxin B1 (AFB1). PorMOF with zirconium ion as the center ion and iron-porphyrin as linker was synthesized. CeO2 nanoparticle was supported on PorMOF to obtain CeO2/PorMOF. PorMOF and CeO2/PorMOF were characterized by scanning electron microscopy, and energy dispersive and X-ray diffraction spectroscopies. CeO2/PorMOF modified electrode showed enhanced electrocatalytic activity for oxygen reduction, and CeO2/PorMOF was functionalized with streptavidin by glutaraldehyde cross-linking to prepare traces of AFB1 aptasensor. A competitive aptasensing assay was applied for AFB1 detection. Firstly, AFB1 capture DNA (cDNA) was fixed on electrode by Au-S bond. Sequentially, AFB1 with biotin was hybridized with cDNA aptamer. Thirdly, after recognizing of biotin and streptavidin, CeO2/PorMOF traces was introduced into electrode to produce a strong electrochemical reduction signal of oxygen. In the presence of AFB1, AFB1 aptamer preferentially bound to AFB1, and the electrochemical signal decreased. The designed method had a wide detection range of 0.1 pM-10 nM, a detection limit as low as 30 fM (S/N = 3), and good selectivity, reproducibility and stability. The aptasensor had been successfully applied to detect AFB1 in peanut and milk samples.