Piezoelectric inkjet assisted rapid electrospray ionization mass spectrometric analysis of metabolites in plant single cells via a direct sampling probe
Direct sampling probe mass spectrometry (DSP-MS) enables fast and direct profiling of metabolites in biological samples. However, because the solvent amount for the online dissolution of acquired analytes is difficult to control, the detection sensitivity is not satisfactory. In this study, we present a modified version of the DSP-MS system for direct mass spectrometric profiling of metabolites in plant single cells. Two major improvements are introduced in this work, including a pointed-tip probe with high surface wetting properties, which is ten times finer than the previous version, and a piezoelectric inkjet system working as the auxiliary solvent delivery means. The probe tip can be controlled to insert into a cell through the cell wall. Metabolites loaded on the tip surface can be extracted by the auxiliary solvent and electrosprayed after applying a high direct current voltage. The unique features such as low cost, disposability and versatility make this technique a competitive tool for single cell analysis.