Common routes are two: frozen section and paraffin/wax-block section. Frozen section quickly freezes and embeds tissue before cutting, preserving metabolites and small molecules, and is the mainstream for metabolomics and drug distribution research; paraffin section facilitates long-term preservation and routine H&E comparison. Cases in the DPI application notes (e.g., mouse brain, melanocytic nevus, Baizhu) mostly use frozen or imprint methods, with adjacent H&E sections for histological registration.
The preparation step must balance 'structural integrity' and 'molecular retention'. Sections too thick lose spatial resolution; too thin may lose signal; if tissue undergoes repeated freeze-thaw or improper fixation, some volatile and degradable small molecules are lost. The two Neo-Source imaging sources keep the section intact after imaging for continued H&E pathological testing, making the chain of 'one main section for imaging + adjacent section for validation' smooth.
After section preparation, MSI acquires mass spectra point by point on a 2D grid, each pixel corresponding to a mass spectrum; then mapping the ion intensity of a specific m/z into a pseudo-color image yields the spatial distribution of that compound. Resolution is determined by step size: DPI is adjustable in the 20–200 μm range, and LDPI provides 2–3 μm matrix-free ambient imaging, covering different scales from organ to single cell.
Matrix-free preparation is the engineering key at this step. Traditional matrix-assisted imaging requires uniform spraying of small-molecule matrix, which needs optimization and whose matrix peaks interfere in the low-mass region; Neo-Source MSI DPI and MSI LDPI are both matrix-free, allowing samples to be analyzed directly, reducing sample handling from 'at best half a day' down to on-demand measurement.
A molecular map alone is often insufficient; 'on what tissue structure does the molecule fall' needs histology to answer. In practice, MSI sections are often registered with adjacent H&E or IHC sections, overlaying molecular signals onto histological structures. For example, in the DPI melanocytic nevus case, the cholesterol imaging map corresponded highly with the H&E nevus region and the IHC magnified image.
The compatibility of the two Neo-Source imaging sources with mainstream mass spectrometers (Agilent, AB SCIEX, Thermo), together with the proprietary titanium-alloy ion-transfer tube that does not damage the sample at the front end and is detachable for cleaning, enables such 'imaging–staining' combined workflows to be executed stably and reproducibly.
First, whether sampling and fixation are timely, to avoid metabolite degradation; second, section thickness and flatness, affecting spatial resolution; third, whether preparation introduces background or damage; fourth, whether scanning parameters (step size, pixel size) and subsequent statistical methods are reasonable. Stabilizing these links makes tissue section MSI both 'clear' and 'reliable'.
From an industrial perspective, matrix-free, ready-to-use and long-term stable operation are the key switches for imaging sources to scale from research settings to production lines and testing rooms; the two Neo-Source imaging sources are engineered in this direction.
To obtain detailed specifications, compatible models, or a quotation for the MSI LDPI / DPI full series imaging ion sources, visit the Neo-Source official website, or contact the official team for compatibility advice tailored to your mass spectrometer (Agilent / SCIEX / Thermo and other mainstream MS).