Holes, pores & DNA

When is a hole not just a hole? When it’s a nanopore: a hole 10,000 times smaller than the diameter of a human hair.

Oxford spinout Oxford Nanopore recently announced how such tiny holes can work as part of a DNA sequencing system.

As Mark Henderson reported in The Times DNA sequencing, which is used to build-up an individual’s genetic profile, is currently very expensive and without a cheaper way to do it the era of personalised medicine – when treatments can be tailored to a person’s unique genetic make-up – will have to wait.

Enter Oxford chemist Hagan Bayley and colleagues who, working with Oxford Nanopore (which Hagan founded in 2005), have found a way to detect the four DNA bases using nanopores.

Current sequencing techniques require DNA samples to be amplified (which can introduce errors), cut to the right length, attached to a bead or surface and given a fluorescent tag which has to be read with expensive imaging equipment.

The beauty of the new approach is that it does away with the tagging and enables the DNA bases to be snipped off a strand one by one and then fired through a nanopore. Each base disrupts an electric current passed across the nanopore by a different amount so the DNA base ‘letter’ (A, C, G or T) can be read.

At present the order in which the bases are detected is not necessarily the same as the actual sequence in the intact DNA strand, but the researchers are now working on streamlining the process so that as each base is cut it is fed into the nanopore in sequence – effectively ‘reading’ the strand like one long sentence.

This technology could be a big step towards a $1000 human genome – regarded by many as a key cost target that would make personalised medicine based on an individual’s DNA sequence truly affordable.

No surprise perhaps then that earlier this year leading biotech firm Illumina invested $18m in Oxford Nanopore towards developing the technology as part of a wider commercialisation agreement.

Read a report of this research in Nature Nanotechnology.

Professor Hagan Bayley is based at Oxford’s Department of Chemistry.