MALDI uses laser irradiation of the matrix-analyte co-crystallized surface to complete desorption and primary ionization; the generated ions are accelerated into the field-free flight tube and separated by flight time (i.e., m/z) before being received by the detector. TOF's instantaneous full-spectrum acquisition characteristic naturally fits imaging point-by-point scanning.
This combination tolerates large molecules such as proteins and peptides well, and the matrix can be optimized for different molecular classes, making it one of the platforms with the widest molecular coverage in tissue imaging.
MALDI-TOF imaging resolution is limited by the laser focal spot and scan step, conventionally on the order of tens of micrometers; transmission-mode MALDI (t-MALDI) can be further optimized. Its high-throughput characteristic is suitable for drawing overall molecular maps of large tissue sections.
For higher resolution needs, combine the high-resolution paths of TOF-SIMS or t-MALDI; for matrix-free, ambient needs, compare matrix-free imaging sources such as LDPI/DPI.
MALDI-TOF relies on sample preparation such as matrix spraying, and the matrix background in the low m/z region may affect small-molecule imaging (small-molecule matrix interference). Choosing a suitable matrix and spraying process is key to signal quality.
The matrix-free route (LDPI, DPI, matrix-free MALDI) can reduce this background, but the molecular gain mechanism differs; projects should choose according to the analyte scale.
MALDI-TOF is widely paired with various mass-spectrometer vendor platforms, and imaging data are often exchanged in imzML and visualized in SCiLS Lab and MetaboScape. For users who want matrix-free imaging with less sample preparation, an externally added LDPI/DPI module can be evaluated.
Selection suggestion: for proteins/peptides/lipids as the main analyte with accepted matrix sample preparation, MALDI-TOF is mature and stable; for small molecules, matrix-free, and ambient as priorities, consider LDPI/DPI.
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).