Facile and controllable hybrid-nanoengineering of MWCNTs/Au@ZIF-8 and AuPt@CeO2 based sandwich electrochemical aptasensor for AFB1 determination in foods and herbs

Herein, a sandwich electrochemical sensing strategy for aflatoxin b₁ (AFB₁) detection based on hybrid-nanoengineering was presented. First, Au nanoparticle was doped into zeolitic imidazolate framework-8 (ZIF-8) to form Au@ZIF-8 by in-situ growth method, followed by multi-walled carbon nanotubes (MWCNTs) addition to synthesize MWCNTs/Au@ZIF-8 via self-assembly. The structural “confinement effect” of ZIF-8 afforded a microenvironment for Au nanoparticles and SMCNTs in a certain spatial region, giving MWCNTs/Au@ZIF-8 excellent electrochemical property as the substrate material. In addition, Au-Pt bimetallic nanoparticle, which exhibited excellent stability and catalytic activity was loaded on the hollow cerium oxide (CeO₂) to form AuPt@CeO₂ nanoparticle through one-step aqueous phase reduction. Owning to its high surface-to-volume ratio, satisfied electron transfer efficiency and biocompatibility, massive toluidine blue (TB) and AFB₁ antibody (Ab) could be modified on the AuPt@CeO₂ to form AuPt@CeO₂-Ab-TB, which acted as signal tag for the ultrasensitive assay of AFB₁. The proposed electrochemical sensing system exhibited wide detection range (2 × 10^-5 − 20 ng/mL) and low detection limit (2.13 fg/mL), which has been successfully applied to AFB₁ determination in four real samples. The hybrid nanoengineering presented in this work is an active attempt to prepare high-performance substrate material and signal tag, which provides a new insight for the development of highly sensitive and specific electrochemical sensing systems.