Design and characterizing of robust probes for enhanced mass spectrometry imaging and spatially resolved metabolomics

As for the emerging and cut edge spatially resolved metabolomics, mass spectrometry imaging (MSI) is a powerful tool that can map thousands of metabolites from bio-tissue sections without chemical labels. However, the stability, sensitivity and spatial resolution of MSI are always limited by the performance of its ionization probe. Herein, two types of probes (fine probe (P-100) and large probe (P-200)) were designed and characterized to perform air-flow assisted desorption electrospray ionization (AFA-DESI) MSI analysis for spatially resolved metabolomics. It was determined that the spray introduced by P-100 was homogenous and stable under the spray solvent at a flow rate of 5-10µL/min, while P-200 can endure a high flow rate of up to 10-30µL/min. Moreover, the MSI images were acquired by AFA-DESI-MSI with P-100 from rat brain tissue section and with P-200 from whole-body tissue section of mouse, and these results presented unambiguous tissue structure with the distribution information of numerous metabolites. Furthermore, the spatially resolved metabolomic analysis of tumor tissue was successfully realized to discover the tumor associated biomarkers. As the key parts of AFA-DESI-MSI system, it has been demonstrated that the designed probs have excellent performance for spatially resolved metabolomics, and it will further promote its application in life science, and drug research and development.