New Structure Mass Tag based on Zr‐NMOF for Multiparameter and Sensitive Single‐Cell Interrogating in Mass Cytometry

Abstract Mass cytometry, also called cytometry by time‐of‐flight (CyTOF), is an emerging powerful proteomic analysis technique that utilizes metal chelated polymer (MCP) as mass tags for interrogating high‐dimensional biomarkers simultaneously on millions of individual cells. However, under the typical polymer‐based mass tag system, the sensitivity and multiplexing detection ability has been highly restricted. Herein, a new structure mass tag based on a nanometal organic framework (NMOF) is reported for multiparameter and sensitive single‐cell biomarker interrogating in CyTOF. A uniform‐sized Zr‐NMOF (33 nm) carrying 10⁵ metal ions is synthesized under modulator/reaction time coregulation, which is monodispersed and colloidally stable in water for over one‐year storage. On functionalization with an antibody, the Zr mass tag exhibits specific molecular recognition properties and minimal cross‐reaction toward nontargeted cells. In addition, the Zr‐mass tag is compatible with MCP mass tags in a multiparameter assay for mouse spleen cells staining, which exploits four additional channels, m/z = 90, 91, 92, 94, for single‐cell immunoassays in CyTOF. Compared to the MCP mass tag, the Zr‐mass tag provides an additional fivefold signal amplification. This work provides the fundamental technical capability for exploiting NMOF‐based mass tags for CyTOF application, which opens up possibility of high‐dimensional single‐cell immune profiling, low abundant antigen detection, and development of new barcoding systems.