Oxford Nanopore Technology (ONT) is a DNA and RNA sequencing technology. It uses nanopores—tiny protein channels embedded in a membrane—to directly read the sequence of nucleic acids (DNA or RNA) by detecting changes in electrical current as the molecules pass through the pores.
Key Concepts of Oxford Nanopore Technology
- How It Works
- Nanopores are tiny protein-based holes embedded in a membrane.
- A voltage is applied across the membrane, and as a single DNA or RNA strand passes through the nanopore, it disrupts the ionic current in a characteristic way.
- These disruptions are recorded and interpreted in real-time to determine the nucleotide sequence.
- Direct Sequencing
- ONT allows:
- Direct DNA sequencing (including long reads >1 Mb).
- Direct RNA sequencing (preserving base modifications).
- Epigenetic detection (e.g., methylation without bisulfite conversion).
- Key Devices
- MinION: A small, USB-powered device suitable for field or lab use.
- GridION: Medium-throughput device for labs.
- PromethION: High-throughput system for large-scale genomics.
- Flongle: Single-use, lower-cost adapter for MinION.
- Applications
- Clinical diagnostics (e.g., pathogen detection, cancer genomics)
- Epidemiology & outbreak surveillance (e.g., Ebola, COVID-19)
- Agrigenomics & environmental monitoring
- Metagenomics & microbiome studies
- Transcriptomics
- Advantages
- Long reads (great for structural variants, de novo assembly)
- Portability (MinION can be used in remote settings)
- Real-time data output
- No PCR required (can preserve original nucleic acid features)
- Challenges
- Lower per-base accuracy (compared to Illumina, though improving)
- Higher error rates in early versions (now mitigated with improved chemistry and basecallers)
- Computational demand for basecalling and error correction
Impact on Science & Medicine
- Democratized Sequencing: Enabled labs worldwide to perform sequencing without expensive infrastructure.
- Outbreak Response: Used to track Ebola, COVID-19, and antimicrobial resistance in real time.
- Personalised Medicine: Supports research into rare diseases and cancer genomics.
Why It’s Revolutionary
- Real-time sequencing – Get data as it’s being generated.
- Ultra-long reads – Reads over 1 million bases are possible.
- Portable devices – Small devices like the MinION fit in a pocket.
- Direct RNA sequencing – Sequence RNA directly without converting it to cDNA.
- Epigenetic detection – Detect base modifications (like methylation) natively.
In summary, Oxford Nanopore Technology offers a flexible, real-time, long-read sequencing platform that is changing the way researchers and clinicians approach genomics.