New two-dimensional nanocomposites combined with target-induced strategy in anelectrochemical aptasensor for sensitive determination of sulfadimethoxine.

Abstract

Ni-Zn bimetallic organic framework nanosheets (NiZn-MOF NSs)were modifiedonto PEI-functionalized MXene for the first time. The combination of the two kinds of nanosheets forms asensing platform with superior conductivity and biocompatibility. On this basis, a highly sensitive biosensor was developed for the determination of sulfadimethoxine (SDM). Furthermore, Au and Mn nanoparticles decorated reduced graphene oxide (Au-Mn/rGO) was introduced as a signal hindering molecule under the target-induced amplification strategy. When theAu-Mn/rGO-labelled SDM-binding aptamer (Au-Mn/rGO-SBA) specifically bound to target SDM, it detached from the electrode, thereby further amplifying the electrochemical signal of [Fe(CN)6]3-/4-. The developed aptasensor for SDM showed excellent response signals in the range 1 pg mL-1 to 100 ng mL-1, with a limit of detection (LOD) as low as 0.22 pg mL-1. Significantly, the proposed sensor also showed satisfactory results in milk samples with recoveries ranging from 87.0 to 96.4% and RSD from 1.5 to 5.1%, which is believedto be useful in food safety assays.