Nanopore label-free detection of single-nucleotide deletion in Baxα/BaxΔ2.

Baxα, a key tumor suppressor gene, will not be expressed correctly as a result of single nucleotide mutation in its microsatellite region; Instead, BaxΔ2, an isoform of Baxα, is often produced. In addition, lack of the exon 2 due to an alternative splicing, BaxΔ2 has the same sequence as Baxα except single base deletion from eight continuous guanines (G8) to G7. Most of the currently available methods for Bax∆2 detection are inefficient and time-consuming, and/or require the use of labels or dyes. In this work, we reported a label-free nanopore sensing strategy to differentiate between Baxα and BaxΔ2 with a DNA polymer as a molecular probe based on alternative spliced sequences. Two DNA molecules were designed to selectively detect Baxα and BaxΔ2, respectively. The method was rapid, accurate, and highly sensitive: picomolar concentrations of target nucleic acids could be detected in minutes. Our developed simple and fast nanopore-based detection strategy is not only useful for distinguishing between Baxα and Bax∆2, but also provides a useful tool for detection of other single-base mutations in genetic diagnosis.