Impedance-Based One-Step Cell Characterization and Preparation for Mass Spectrometry Analysis

Single-cell analysis has gained widespread attention in biological and clinical research, with latest efforts on the comprehensive characterization methods of cellular bio-physical and bio-chemical properties. Among these, impedance flow cytometry (IFC) and mass spectrometry (MS) detection are two important cell analysis methods. However, current research typically focused on either one, lacking the platform for characterization of both properties. In this chapter, we focus on the joint detection of impedance and MS through microfluidic technology, with the long-term goal to achieve combined physical and chemical analysis of single cells. As a key step, efficient sample preparation like sorting (i.e., separating target cells from mixed populations) and desalting (i.e., moving the cells off non-volatile salt solution) is urgently required. We propose a one-step sample preparation strategy by leveraging label-free IFC-based microfluidics. Specifically, we adopt the IFC framework to characterize and sort single cells. Simultaneously with sorting, the target cell is transferred from local high-salinity buffer to the MS-compatible solution. In this way, one-step sorting and desalting are achieved and the collected cells can be directly used for MS analysis, with the combined analysis achieved.