dCITI-Seq: droplet combinational indexed transposon insertion sequencing.

The rapid development of high-throughput parallel sequencing poses new challenges for large-scale barcoding and sequencing library construction. Here, we present droplet combinational indexed transposon insertion sequencing (dCITI-Seq), in which samples are indexed by the direct insertion of index-containing adaptors through transposition. The random combination of two sets of adaptors with known barcodes and massively parallel transposition was realized via a robust droplet pairing and merging platform. This strategy potentially enlarges the indexing capacity and decreases index crosstalk. Also, dCITI-Seq exhibited a lower GC base preference than conventional in-tube transposition library preparation. With a custom bioinformatic processing, it could be further applied to large-scale single-cell sequencing.