Versatile applications of MS imaging using a bench-top linear MALDI-TOFMS

Importance of the topic

This work demonstrates how a compact bench-top MALDI-TOF mass spectrometer can extend access to high-resolution molecular imaging across diverse fields. Traditional high-end instruments often impose barriers due to size, cost, and complexity. A more accessible, easy-to-use platform enables food-safety screening, forensic analyses, pharmaceutical research, and industrial material evaluation without sacrificing critical spatial resolution.

Objectives and overview of the study

The primary aim was to evaluate the performance of the Shimadzu MALDI-8020 bench-top linear MALDI-TOFMS for imaging applications at 30–50 µm spatial resolution. Four representative samples were selected:

• Rat brain tissue for lipid distribution mapping
• Soybean seed treated with a pesticide
• Latent fingermark on stainless steel
• Polyethylene terephthalate (PET) film under various heat-stress conditions

The study sought a streamlined workflow combining rapid matrix deposition, straightforward data acquisition, and user-friendly visualization software.

Methodology

Samples were prepared as frozen or heat-treated sections:

• Soybean seeds were cryosectioned after pesticide exposure.
• Rat brain sections were provided by a molecular imaging center.
• Fingermarks were collected by direct finger impression on steel plates.
• PET films were treated at different temperatures for up to 18 hours.

Matrix application methods:

• 2,5-Dihydroxybenzoic acid (DHB) sublimated onto tissue and fingermarks using an iMLayer device.
• α-Cyano-4-hydroxycinnamic acid (CHCA) sublimated onto seed sections.
• Dithranol with sodium iodide sprayed onto PET films.

Imaging parameters:

• Positive ion mode at 200 Hz laser repetition rate.
• Spatial resolution set to 30 µm for biological specimens and 50 µm for seeds and films.

Instrumentation

The workflow relied on:

• Shimadzu MALDI-8020 bench-top linear MALDI-TOFMS.
• iMLayer matrix deposition system (Shimadzu).
• IonView and IMAGEREVEAL software for data visualization.

Main results and discussion

Imaging of rat brain tissue at 30 µm resolution revealed distinct lipid distributions, with data points exceeding 84,000 per frame. Soybean seed sections imaged at 50 µm showed sodium adducts of the pesticide localized predominantly on the surface layer. Fingermark analysis provided high-contrast lipid maps at 30 µm resolution, capturing ridge details in over 23,000 data points. PET film “mapping” under heat stress visualized cyclic PET oligomers, confirming the suitability of the method for polymer film surface assessment.

Benefits and practical applications of the method

The bench-top system offers:

• Compact size and cost efficiency compared to high-end imaging platforms.
• Rapid setup and simple matrix deposition workflows.
• Sufficient spatial resolution for many QA/QC, forensic, and food-safety tasks.
• Easy data handling and visualization via dedicated software.

Future trends and potential applications

Further developments may include:

• Integration with automated sample handling to boost throughput.
• Enhanced software incorporating multivariate analysis for rapid biomarker discovery.
• Expansion into clinical tissue imaging and pharmaceutical distribution studies.
• Adoption in on-site industrial monitoring of polymer degradation and contamination.

Conclusion

The study confirms that a bench-top linear MALDI-TOFMS can deliver reliable MS imaging at 30–50 µm resolution across multiple sample types. Its simplicity and accessibility pave the way for broader adoption in research, industry, and quality control, reducing reliance on larger, more complex instrumentation.