Identifying RNA transcript isoforms requires intricate protocols that suffer from various enzymatic biases. Here we design three-dimensional molecular constructs that enable identification of transcript isoforms at the single-molecule level using solid-state nanopore microscopy. We refold target RNA into RNA identifiers with designed sets of complementary DNA strands. Each reshaped molecule carries a unique sequence of structural (pseudo)colours. Structural colours consist of DNA structures, protein labels, native RNA structures or a combination of all three. The sequence of structural colours of RNA identifiers enables simultaneous identification and relative quantification of multiple RNA targets without prior amplification. Our Amplification-free RNA TargEt Multiplex Isoform Sensing (ARTEMIS) method reveals structural arrangements in native transcripts in agreement with published variants. ARTEMIS discriminates circular and linear transcript isoforms in a one-step, enzyme-free reaction in a complex human transcriptome using single-molecule read-out.

https://doi.org/10.1038/s41557-022-01037-5 -2022