Single nucleotide detection using bilayer MoS 2 nanopores with high efficiency.

Single nucleotide detection is important for early detection of diseases and for DNA sequencing. Monolayer (ML) MoS 2 nanopores have been used to identify and distinguish single nucleotides with good signal-to-noise ratio in the recent past. Here, we use a bilayer (BL) MoS 2 nanopore (∼1.3 nm thick) to detect distinct single nucleotides with high spatial resolution and longer dwell time. In this study, the performance of similar sized (<3 nm) ML and BL MoS 2 nanopores for detection of a single nucleotide has been compared. Both single nucleotide and single stranded DNA translocations through them are studied. For single nucleotide detection, we observe that BL MoS 2 nanopores demonstrate twice the dwell time as compared to ML MoS 2 nanopores with 95% confidence. Single nucleotide detection rate for BL MoS 2 nanopores (50-60 nucleotides per s) is five-fold higher as compared to ML MoS 2 nanopores (10-15 nucleotides per s) in 10 pM analyte concentration. For single stranded DNA, we observe 89% (for 60 DNA molecules detected) single nucleotide detection efficiency with BL MoS 2 nanopores as compared to 85% for ML MoS 2 . The DNA sequencing efficiency through BL MoS 2 nanopores is also found to be 8-10% better than through ML MoS 2 nanopores, irrespective of DNA sequencing orientation. Thus, owing to improved analyte/nanopore charge interaction BL MoS 2 nanopores can be used for single nucleotide detection with high resolution due to longer dwell time, detection rate and efficiency. This study demonstrates the improved ability of BL MoS 2 nanopores in sequencing DNA with 8-10% higher efficiency, two-times temporally resolved single-nucleotide current signatures and five-times higher detection rate, compared to ML MoS 2 nanopores.