CNT-Modified MIL-88(NH2)-Fe for Enhancing DNA-Regulated Peroxidase-Like Activity

Abstract

Over the past few decades, the enzyme-mimicking activity of metal–organic frameworks (MOFs) accompanied with structural characteristics has aroused much attention. However, pure MOFs have low affinity with DNA. Here, iron-based MOFs with acidized carbon nanotubes (CNTs) via a simple hydrothermal process have been synthesized, named as MIL-88(NH2)-Fe@CNTs. CNTs can enhance the affinity between MOF and DNA, achieving flexible regulation of their catalytic activity benefiting from the strong π − π stacking between CNTs and DNA. Meanwhile, in comparison with conventional iron-based MOFs, the addition of CNTs, which contributes to the acceleration of electron transfer, endowing as-prepared nanocomposites remarkably enhanced peroxidase-like activity to achieve an ultrasensitive detection of H2O2 with the LOD of 17.64 μg/L. Notably, the as-prepared nanocomposites with adsorbed DNA displayed excellent affinity towards both TMB (3, 3′, 5, 5′-tetramethylbenzidine) substrates and H2O2 as well as high catalytic velocity. On the basis of their switchable peroxidase-like activity regulated by different length or sequence of ssDNA, it is believed that our-prepared MOF-based nanomaterials would be promising for fabricating versatile and sensitive label-free colorimetric assays for diverse targets.