Molecular tagging with nanopore-orthogonal DNA strands

Molecular tagging is an approach using DNA or other molecules to label and identify physical objects of high value. An ideal tagging system would be simple to use end-to-end (i.e. no third-party service needed), quick and reliable to decode, available "on-demand", and require minimal specialist equipment. Katie described how she has created a molecular tagging system using DNA-based tags and the MinION nanopore sequencing platform for their detection.

Katie firstly described how molecular tags are encoded: strands are designed as molecular bits ("molbits"), which are comprised of a unique sequence of a specific length. These molbits can be classified directly from the raw nanopore signal data, without the need for basecalling, thereby reducing compute time and the potential for classification errors. A simple binary code can be used, representing presence (1) or absence (0) within a tag. With this approach, only 3-5 minutes of nanopore sequencing is required for tag identification. Katie presented an example squiggle plot that had been cleverly designed to show the letters U and W within the squiggles, which had been specifically encoded by the molbits sequenced, representing the University of Washington where she is based.

Katie concluded her talk by explaining how molbits themselves are stabilised in their physical form by dehydration; this extends their shelf time and makes them robust to contamination from environmental DNA. This means that you can simply "just add a drop of water and throw them on the MinION".