Novel impedimetric sensing strategy for detecting ochratoxin A based on NH2-MIL-101(Fe) metal-organic framework doped with cobalt phthalocyanine nanoparticles

Iron-based metal-organic framework, NH2-MIL-101(Fe), was doped with different dosages of cobalt phthalocyanine nanoparticles (CoPc) to synthesize a series of NH2-MIL-101(Fe)@CoPc nanocomposites. The NH2-MIL-101(Fe)@CoPc nanocomposites were then employed to construct novel impedimetric aptasensors for the detection of ochratoxin A (OTA). Combining the intrinsic advantages of NH2-MIL-101(Fe) (highly porous structure and excellently electrochemical activity) and CoPc (good physiochemical stability and strong bioaffinity), the NH2-MIL-101(Fe)@CoPc nanocomposites show promising properties, which are beneficial for immobilizing OTA-targeted aptamer strands. Amongst, the developed impedimetric aptasensor based on NH2-MIL-101(Fe)@CoPc6:1, prepared using the mass ratio of NH2-MIL-101(Fe):CoPc of 6:1, exhibits the best amplified electrochemical signal and highest sensitivity for detecting OTA. The detection limitation is 0.063 fg·mL−1 within the OTA concentration of 0.0001–100 pg·mL−1, accompanying with high selectivity, good reproducibility and stability, acceptable regenerability, and wide applicability in diverse real samples. Consequently, the proposed sensing strategy can be applied for detecting OTA to cope with food safety.