Single nucleotide detection using bilayer MoS2 nanopores with high efficiency†
Abstract
Single nucleotide detection is important for early detection of diseases and for DNA sequencing. Monolayer (ML) MoS2 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) MoS2 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 MoS2 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 MoS2 nanopores demonstrate twice the dwell time as compared to ML MoS2 nanopores with 95% confidence. Single nucleotide detection rate for BL MoS2 nanopores (50–60 nucleotides per s) is five-fold higher as compared to ML MoS2 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 MoS2 nanopores as compared to 85% for ML MoS2. The DNA sequencing efficiency through BL MoS2 nanopores is also found to be 8–10% better than through ML MoS2 nanopores, irrespective of DNA sequencing orientation. Thus, owing to improved analyte/nanopore charge interaction BL MoS2 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 MoS2 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 MoS2 nanopores.