On-chip single-cell mass spectrometry for streamlined metabolic exploration enabled by a reversibly-bonded...

Single-cell mass spectrometry (SCMS) deepens the insight into current bioanalytical science. Precise cell positioning is a critical step in SCMS workflow because it provides accurate spatial coordinates of the target cell for downstream analysis. However, conventional approaches rely on manual cell localization, resulting in compromised analysing throughput. Microfluidic techniques exhibit inherent advantages in rare cell isolation, whereas the encapsulation nature of the microfluidic chip confines the cells in a sealed chamber, making it incompatible with subsequent cellular extraction and mass spectrometry.

In this study, we developed a reversibly-bonded microfluidic chip that achieves seamless integration with SCMS workflow. Our method features a flexible bonding strategy where the chip maintains bonding stability during cell isolating stage, followed by controlled disassembly to expose the entrapped cells into ambient environment for on-chip SCMS analysis. The results show that single-cells are patterned in geometrically defined positions within 4 min based on size-dependent trapping mechanics, enabling deterministic spatial addressing. In addition, the precisely-engineered cellular trap creates discrete microenvironments for single-cell sampling, and the compartmentalization of the extracting droplet prevents intercell cross-talk in SCMS procedure. The established platform demonstrates exceptional efficacy in single-cell metabolic analysis, as evidenced by the successful detection of 170 metabolites in bladder cancer cells and cellular subtyping is readily achieved based on metabolic fingerprints.

The integration of reversible microfluidics and SCMS bridges the gap between high-throughput cell manipulation and post-processing analysis, representing a novel way for single-cell metabolomics studies.