Modular lanthanide barcodes for high-throughput single-cell analysis by mass cytometry

The comprehensive identification of diverse cellular populations at single-cell resolution remains a central challenge in biomedical research. Mass cytometry is a powerful and sensitive platform that uses rare earth metal isotopes instead of fluorophores, yet its multiplexing capacity is fundamentally constrained by the limited number of distinguishable lanthanides. Here, we present a modular metal-encoding strategy to expand multiplexing capability through combinatorial lanthanide barcoding. By assembling lanthanide-DOTA chelates as monomeric building blocks, we constructed a theoretical C_15^1+C_15^2+C_15^3+C_15^4…barcoding matrix based on 15 lanthanides, enabling up to 35,715 unique molecular codes. One barcode species was conjugated to an anti-CD45 antibody, demonstrating its ability to enable clear discrimination of distinct cell populations and highlighting its potential for labeling diverse biomolecular and cellular targets.