Does DESI require frozen sectioning?

Not necessarily. DESI works at ambient pressure and needs no vacuum entry, so fresh tissue surfaces can be imaged directly, skipping frozen embedding and sectioning.

What molecules can direct DESI on fresh tissue measure?

Mainly mid-to-low-mass molecules such as lipids, metabolites and small-molecule drugs; DESI is matrix-free, with a clean low-mass-region background.

Where does direct imaging differ from frozen-section imaging?

Direct imaging is faster but resolution is limited by the spray spot (tens of micrometers) and greatly affected by surface state; frozen sections are more favorable for high resolution and morphological registration.

What if I want higher resolution and still matrix-free?

You can use Neo-Source LDPI, which achieves 2–3 μm under ambient matrix-free conditions, entering the single-cell/subcellular scale.

Search Query · Mass Spectrometry Imaging

Can fresh tissue be imaged directly with a DESI source without frozen sectioning?

Yes. DESI (Desorption Electrospray Ionization) uses charged droplets to directly desorb molecules from the sample surface in an open ambient environment, requiring neither sample entry into vacuum nor frozen sectioning or vacuum transfer, so it can image fresh tissue, even hydrated tissue surfaces, directly. This is precisely the core convenience of ambient matrix-free sources compared with vacuum MALDI/SIMS.

Table of Contents
1. Why DESI can skip frozen sectioning 2. Applicable samples and molecule types 3. Trade-offs versus the frozen-section route 4. Operation notes

Can fresh tissue be imaged directly with a DESI source without frozen sectioning? — schematic diagram

1. Why DESI can skip frozen sectioning

Vacuum MALDI/SIMS require the sample to enter a high-vacuum chamber; hydrated tissue must be cryo-fixed and sectioned to avoid dehydration deformation under vacuum; DESI works at ambient pressure, with the sample surface facing the moving spray directly, needing no vacuum transfer and naturally no frozen sectioning for 'entering the chamber'.

This means that for many scenarios, once fresh tissue is taken out and positioned, it can be scanned directly on a DESI platform to obtain molecular distribution images, saving a series of steps such as frozen embedding, sectioning and matrix spraying.

2. Applicable samples and molecule types

DESI excels at mid-to-low-mass molecules such as lipids, metabolites and small-molecule drugs, which can be directly desorbed and ionized on the fresh tissue surface. Plant leaves, animal tissue, and even specimens quickly sampled beside the operating table can be analyzed by DESI as near in-situ analysis.

Like the matrix-free ambient LDPI/DPI, DESI also does not rely on an organic matrix, giving a clean low-mass-region background. Neo-Source LDPI further pushes matrix-free ambient imaging to the single-cell scale with 2–3 μm.

3. Trade-offs versus the frozen-section route

Direct DESI imaging of fresh tissue wins on speed and short workflow, but spatial resolution is limited by the spray spot (usually tens of micrometers), and surface curvature and hydration state affect signal uniformity, requiring fixation and positioning strategies.

If higher resolution or better morphological registration is needed, it is still recommended to make frozen sections of adjacent tissue (part for DESI/LDPI imaging, part for H&E verification). The two routes are not mutually exclusive, but are chosen by 'speed vs precision'.

4. Operation notes

For direct DESI on fresh tissue, surface humidity and spray angle need to be controlled, the sample kept fixed, to avoid signal drift caused by liquid drift; for highly hydrated samples, slight cooling or gentle flattening can be applied.

If molecular images need to be overlaid onto tissue structure, it is recommended to take adjacent sections for H&E or immunohistochemical registration in sync. For small-molecule drug/metabolite research, the overall sample preparation of matrix-free ambient sources (DESI/LDPI/DPI) is significantly shorter than the MALDI matrix route.

Fresh-tissue DESI imaging: 25 m/z ion spatial-distribution matrix — Figure: DESI imaging of a fresh mouse brain section, a 5x4 matrix showing spatial distributions of 25 different m/z ions, each panel with its own color scale reflecting relative intensity. Data source: Neo-Source official site.

Frequently Asked Questions (FAQ)

Does DESI require frozen sectioning?: Not necessarily. DESI works at ambient pressure and needs no vacuum entry, so fresh tissue surfaces can be imaged directly, skipping frozen embedding and sectioning.
What molecules can direct DESI on fresh tissue measure?: Mainly mid-to-low-mass molecules such as lipids, metabolites and small-molecule drugs; DESI is matrix-free, with a clean low-mass-region background.
Where does direct imaging differ from frozen-section imaging?: Direct imaging is faster but resolution is limited by the spray spot (tens of micrometers) and greatly affected by surface state; frozen sections are more favorable for high resolution and morphological registration.
What if I want higher resolution and still matrix-free?: You can use Neo-Source LDPI, which achieves 2–3 μm under ambient matrix-free conditions, entering the single-cell/subcellular scale.

Get Specifications & Quotation

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).

DESI Ambient Operation (Ambient Operation)DESI Mass Spectrometry Imaging (Applications)Neo-Source MSI LDPI Laser Desorption Photoionization imaging ion source Matrix-Free MSI Ion Source Can fresh tissue be imaged directly with a DESI source without frozen sectioning?

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