Concentration effects on capture rate and translocation configuration of nanopore-based DNA detection

Exploring the non-monotonic DNA capture behavior in a charged graphene nanopore

Nanopore-based biomolecule detection has emerged as a promising and sought-after innovation, offering high throughput, rapidity, label-free analysis, and cost-effectiveness, with potential applications in personalized medicine. However, achieving efficient and tunable biomolecule capture into the nanopore remains a significant challenge. In this study, we employ all-atom molecular dynamics simulations to investigate the capture of double-stranded DNA (dsDNA) molecules into graphene nanopores with varying positive charges. We discover a non-monotonic relationship between the DNA capture rate and the charge of the graphene nanopore. Specifically, the capture rate initially decreases and then increases with an increase in nanopore charge. This behavior is primarily attributed to differences in the electrophoretic force, rather than the influence of electroosmosis or counterions. Furthermore, we also observe this non-monotonic trend in various ionic solutions, but not in ionless solutions. Our findings shed light on the design of novel DNA sequencing devices, offering valuable insights into enhancing biomolecule capture rates in nanopore-based sensing platforms.

Sequence-Specific Detection of DNA Strands Using a Solid-State Nanopore Assisted by Microbeads

Simple, rapid, and low-cost detection of DNA with specific sequence is crucial for molecular diagnosis and therapy applications. In this research, the target DNA molecules are bonded to the streptavidin-coated microbeads, after hybridizing with biotinylated probes. A nanopore with a diameter significantly smaller than the microbeads is used to detect DNA molecules through the ionic pulse signals. Because the DNA molecules attached on the microbead should dissociate from the beads before completely passing through the pore, the signal duration time for the target DNA is two orders of magnitude longer than free DNA. Moreover, the high local concentration of target DNA molecules on the surface of microbeads leads to multiple DNA molecules translocating through the pore simultaneously, which generates pulse signals with amplitude much larger than single free DNA translocation events. Therefore, the DNA molecules with specific sequence can be easily identified by a nanopore sensor assisted by microbeads according to the ionic pulse signals.