Zr-NMOF Tagged with Heterobifunctionalized Aptamers for Highly Sensitive, Multiplexed and Rapid Imaging Mass Cytometry

Imaging mass cytometry (IMC) permits high-dimensional single-cell spatial proteomics by harnessing mass tags to replace conventional fluorescence tags. However, the current IMC technique commonly adopts metal-chelated polymer (MCP) tags, which are limited in sensitivity, multiplicity and data acquisition speed. Here, we demonstrate nanometal-organic framework (NMOF) tags, which could concurrently augment IMC's sensitivity, multiplicity, and acquisition speed. We designed and synthesized uniform-sized Zr-NMOFs (∼31 nm, PDI < 0.1) and then functionalized them with heterobifunctionalized aptamers containing phosphate groups and fluorescent moieties to generate Zr-NMOF_Aptamer probes. Such functionalization enabled direct ligand exchange with zirconium ions on Zr-NMOFs, thus allowing for concurrent fluorescence and mass signal acquisitions. The fluorescence signal enabled large-scale rapid imaging to quickly locate the region-of-interest, therefore significantly reducing IMC's blind scanning time and compensating for IMC's lower resolution. Meanwhile, the Zr-NMOF_Aptamer probe exhibited specific molecular recognition and a fourfold enhancement in signal amplification over the commercial MCP probe. Additionally, we showed that Zr-NMOF_Aptamer probes were compatible with commercial MCP probes for high-multiplex co-staining in IMC analysis. The Zr-NMOF_Aptamer probe represents a promising development of next-generation molecular probes for spatial proteomics with IMC.