Direct and Real-Time Surface Analysis and Imaging of Biological Samples by Probe Electrospray

Abstract

Recently, we have developed the probe electrospray ionization (PESI) that uses the solid needle. In this system, the probe needle moves up and down along the vertical axis by a motor-driven system. At the highest position of the probe needle, electrospray is generated by applying the high voltage. In this study, we used PESI directly to the biological samples such as urine, mouse brain, mouse liver, salmon egg, artificial salmon egg, and fruits (orange, banana, etc.). Strong ion signals for almost all the samples were obtained. The amount of liquid sample picked up by the needle is as small as pL or less, making the PESI the most promising non-invasive technique for detecting biomolecules in a living systems such as cells. Therefore, PESI may be useful as versatile and ready-to-use semi-on line analyses in the fields of surface chemistry, medicine, pharmaceutical, agriculture, food science, etc.