Interfacial Nanoinjection‐Based Nanoliter Single‐Cell Analysis

Abstract Single‐cell analysis offers unprecedented resolution for the investigation of cellular heterogeneity and the capture of rare cells from large populations. Here, described is a simple method named interfacial nanoinjection (INJ), which can miniaturize various single‐cell assays to be performed in nanoliter water‐in‐oil droplets on standard microwell plates. The INJ droplet handler can adjust droplet volumes for multistep reactions on demand with high precision and excellent monodispersity, and consequently enables a wide range of single‐cell assays. Importantly, INJ can be coupled with fluorescence‐activated cell sorting (FACS), which is currently the most effective and accurate single‐cell sorting and isolation method. FACS‐INJ pipelines for high‐throughput plate well‐based single‐cell analyses, including single‐cell proliferation, drug‐resistance testing, polymerase chain reaction (PCR), reverse‐transcription PCR, and whole‐genome sequencing are introduced. This FACS‐INJ pipeline is compatible with a wide range of samples and can be extended to various single‐cell analysis applications in microbiology, cell biology, and biomedical diagnostics.