Modulating Interfacial Fluid Dynamics for Enhanced Proteoform Analysis Using Nano-DESI Mass Spectrometry

Proteoform imaging mass spectrometry (PiMS) using nano-DESI MS enables label-free detection of thousands of intact proteoforms from biological tissue sections and single cells. However, proteome coverage using this approach is limited by the liquid extraction process at the solvent–tissue interface. Here, we demonstrate a simple approach using tailored primary capillary probe size and geometry to enhance proteoform detection. Intriguingly, we found that the enhancement factor strongly depends on the molecular weight and subcellular localization of the proteoforms. We rationalized these observations by dissecting the theory of interfacial fluid dynamics within the nano-DESI liquid bridge. These principles were further leveraged to achieve proteoform detection in surface-immobilized single cells with enhanced sensitivity and throughput.