Correlative Chemical Imaging: Integration of Mass Spectrometry Imaging and Fluorescence Microscopy for Comprehensive Lipid Analysis

Mass spectrometry imaging (MSI) provides robust spatially resolved chemical information by generating heat-map images from different mass-to-charge ratio (m/z) species, while fluorescence microscopy offers optical-level resolution but limited chemical specificity. Integrating these complementary modalities can produce a more comprehensive view of lipid distributions and structures in tissues.
Among MSI techniques, Desorption electrospray ionization (DESI) MSI offers the advantage of a gentle and non-destructive in situ extraction mechanism, which allows sequential experiments on the same sample. Another advantage of DESI is to incorporate derivatization methods in droplet chemistry that are frequently employed to enhance analyte signals and provide additional chemical structural information.
We have developed a multifunctional lipid tag that targets lipid double bonds in situ to facilitate double bond position identification through DESI MSI, while simultaneously enabling fluorescence imaging within the same tissue sample. The fluorescence imaging provides a lipid unsaturation distribution map with optical-level spatial resolution, allowing detailed structural visualization within the sample. Complementarily, mass spectrometry imaging delivers in-depth chemical information to enable lipid structural identification. By integrating these two imaging techniques, we can generate enhanced spatial resolution mass spectrometry images from the same exact sample.