Label-free electrochemical biosensor using home-made 10-methyl-3-nitro-acridone as indicator for picomolar detection of nuclear factor kappa B

• A new electrochemical indicator 10-methyl-3-nitro-acridone (MNA) with excellent and stable electrochemical activity in neutral condition was synthesized.
• A signal-on and label-free electrochemical biosensor based on MNA was developed for picomolar determination of nuclear factor kappa B.
• This is the first study to use acridone derivative as electrochemical indicator for nuclear factor kappa B detection.

A new acridone derivative 10-methyl-3-nitro-acridone (MNA) with excellent electrochemical activity was synthesized in this paper. Using it as an electrochemical indicator, a signal-on and label-free electrochemical biosensor was developed for picomolar determination of nuclear factor kappa B (NF-κB) in serum. Initially, linear double-stranded DNA (dsDNA) probes, which contain a protein-binding site specific to NF-κB, were self-assembled on the surface of a glass carbon electrode (GCE). If the NF-κB was absent, the dsDNA probes were cut into ss-DNA fragments by the digestion of ExoIII, resulting in a low electrochemical signal of MNA due to the weak binding affinity of MNA to ss-DNA. On the contrary, in the presence of NF-κB, it could bind with the dsDNA probes at the specific site and hinder the digestion of ExoIII, resulting in a significant increase of electrochemical response due to the intercalation of MNA into the dsDNA probes. By employing the above strategy, this sensor could detect as low as 40 pM NF-κB with high specificity. To the best of our knowledge, the proposed sensor is the first attempt to use acridone derivative as an electrochemical indicator for NF-κB detection, which may represent a promising path toward clinical diagnosis and drug developments.