Morpholino-Functionalized Nanochannel Array for Label-Free Single Nucleotide Polymorphisms Detection

The sensitive identification of single nucleotide polymorphisms becomes increasingly important for disease diagnosis, prevention, and practical applicability of pharmacogenomics. Herein, we propose a simple, highly selective, label-free single nucleotide polymorphisms (SNPs) sensing device by electrochemically monitoring the diffusion flux of ferricyanide probe across probe DNA/morpholino duplex functionalized nanochannels of porous anodic alumina. When perfectly matched or mismatched target DNA flows through the nanochannels modified with probe DNA/morpholino duplex, it competes for the probe DNA from morpholino, resulting in a change of the surface charges. Thus, the diffusion flux of negatively charged electroactive probe ferricyanide is modulated since it is sensitive to the surface charge due to the electrostatic interactions in electric double layer-merged nanochannels. Monitoring of the change in diffusion flux of probe enables us to detect not only a single base or two base mismatched sequence but also the specific location of the mismatched base. As is demonstrated, SNPs in the PML/RAR alpha fusion gene, known as a biomarker of acute promyelocytic leukemia (APL), have been successfully detected.