Microfluidic Sample Preparation for Multiplexed Single-Cell Proteomics Using a Nested Nanowell Chip.

Mass spectrometry-based single-cell proteomics has undergone rapid progress and has become an active research area. However, because of the ultralow amount of proteins in single cells, it is still highly challenging to achieve efficient sample preparation and sensitive LC-MS detection. Here, we provide a detailed protocol for isobaric labeling-based single-cell proteomics relying on a microfluidic droplet-based sample processing technology. The protocol allows for processing both single cells and carrier samples in separate microchips using a commercially available platform (cellenONE) with high sample recovery and high throughput. We also provide an optimized LC-MS method for sensitive and robust data collection.