Nanopore

Nanopore sequencing is a method of determining the sequence of nucleic acids by threading a single molecule through a nanopore and measuring changes in ionic current. A membrane containing a nanopore is placed between two electrolyte-filled chambers, and an electric potential drives molecules through the pore. Each nucleotide or short sequence of bases causes characteristic disruptions in the current, which are interpreted by basecalling algorithms to infer the sequence. Nanopore technology can use biological nanopores in protein channels, such as alpha-hemolysin or MspA, or solid-state nanopores fabricated in synthetic membranes.

A major commercial platform is produced by Oxford Nanopore Technologies, including the portable MinION and the larger GridION and PromethION devices. Advantages of nanopore sequencing include very long read lengths, real-time data output, and portability, along with the ability to sequence native DNA or RNA without amplification and to detect DNA base modifications such as methylation directly from the signal. Challenges have included historically higher per-read error rates compared with some other sequencing methods, though accuracy has improved with advances in chemistries, basecalling algorithms, and consensus approaches.

Nanopore sequencing has been applied to de novo genome assemblies, structural variation detection, transcriptome analysis, and epigenetic studies. Data processing typically involves converting the current signal into nucleotide sequences, followed by alignment, assembly, and variant calling. The technology is valued for field deployments, long contiguous reads, and versatile applications, while requiring careful interpretation for some analyses.