A novel amperometric adenosine triphosphate biosensor by immobilizing graphene/dual-labeled aptamers complex onto poly(o-phenylenediamine) modified electrode

Graphene (GR) can strongly interact with aptamers due to hydrophobic and π-π stacking interactions between nucleotide bases and GR, but hardly interact with aptamer-target complexes or rigid double-stranded DNA. The unique GR/aptamers interaction has been fascinatingly developed in fluorescent assay, colorimetric biosensing and mass spectrometric analysis. However, exploration of the unique GR/aptamers interaction in electrochemical biosensing is still at an early stage. In this regard, we reported herein a novel, sensitive and relatively cushy approach to construct electrochemical aptasensors by immobilizing GR/aptamers complex on the surface of poly(o-phenylenediamine) (PoPD) modified glassy carbon electrodes (GCE). Adenosine triphosphate (ATP) was chosen as a model analyte and a well-studied 27-mer single-stranded DNA aptamer was tailor-made to have methylene-blue (Mb) at both ends for use as an electrochemical probe. The Mb-dual-labeled aptamers/GR/PoPD/GCE exhibited a strong electrochemical signal due to the high electrons transfer and large surface area of GR and using double Mb labeled at two ends of aptamers. The presence of ATP triggers the structure switching of aptamer to form aptamer-ATP complex, causing the destruction of the interaction between aptamer and GR and thus the release of Mb-dual-labeled aptamer from the GR, resulting in a low electrochemical signal. Under optimal conditions, we have successfully detected ATP down to a detection limit of 0.3 nM with a wide detection range of 10 nM-2 mM. And from the experiment of cancer cellular ATP assay, it is proved that the method may have great prospects in the field of biological analysis.