Nanopore Filter: A Method for Counting and Extracting Single DNA Molecules Using a Biological Nanopore.

Area of Science:

• Biotechnology
• Nanotechnology
• Molecular Biology

Background:

• Nanopore technology enables electrochemical single-molecule detection without labeling.
• Existing methods face challenges in precise single-molecule counting, particularly due to contamination.
• Accurate quantification of DNA molecules is crucial for various biological applications.

Purpose of the Study:

• To develop a DNA filtering system for real-time, single-molecule counting using an alpha-hemolysin (αHL) nanopore.
• To investigate the feasibility of electrical current measurements for quantifying translocated DNA molecules.
• To address and mitigate contamination issues inherent in single-molecule counting.

Main Methods:

• Utilized an alpha-hemolysin (αHL) nanopore embedded in a planar lipid bilayer separating two droplets.
• Monitored DNA molecule translocation through the nanopore by measuring changes in channel electrical current.
• Validated molecule counts using quantitative polymerase chain reaction (qPCR) and implemented optimization strategies like the PCR clamp method.

Main Results:

• Observed DNA translocation events through the αHL nanopore via electrical current changes.
• Identified contamination as a significant obstacle to accurate single-molecule counting.
• Demonstrated a linear relationship between electrical counting and qPCR-based estimations of DNA molecule numbers.
• Showcased the potential of the developed system despite ongoing challenges with achieving precise electrical counting.

Conclusions:

• The developed nanopore-based system shows promise for real-time DNA molecule counting.
• Contamination remains a critical challenge requiring further investigation and mitigation strategies.
• The observed linear correlation between electrical and qPCR methods supports the system's potential for quantitative analysis.