Rapid screening of brain tissue with a high spatial resolution over large analysis areas using Agilent’s 670 and 620 FTIR imaging analysis

Significance

Infrared imaging at high spatial resolution enables detailed chemical mapping of biological tissues without altering sample integrity. This approach is vital for understanding pathological processes, such as those occurring in Alzheimer’s disease, by correlating molecular signatures with morphological features at the cellular level.

Objectives and Study Overview

The study aimed to rapidly screen an entire hippocampus section from a mouse brain to determine the relationship between tissue chemical composition, protein secondary structure, and morphological changes. By applying FTIR imaging over a large area with micron-level resolution, the research sought to reveal chemical markers associated with Alzheimer’s pathology, including amyloid plaques and tau tangles.

Methodology and Instrumentation

All measurements were conducted using a high‐throughput FTIR imaging system combining an Agilent Cary 670 FTIR spectrometer with an Agilent Cary 620 FTIR microscope. Key instrument settings and methods included:

• Detector: 64×64 focal plane array (FPA), 5.5 μm pixel resolution
• Mode: Reflection mosaic imaging (4×6 tiles) to cover the entire hippocampus (1.4 mm × 2.2 mm)
• Spectral resolution: 4 cm⁻¹, 128 scans per pixel, scan rate 5 kHz
• Software: Agilent Resolutions Pro for automated, unattended large‐area data acquisition and processing

This configuration allowed collection of ~100 000 spectra in approximately 30 minutes, significantly faster than conventional IR mapping or synchrotron‐based methods.

Main Results and Discussion

Rapid acquisition produced two‐dimensional and three‐dimensional chemical images that distinctly visualized white matter, gray matter, and individual neurons. Key findings included:

• Clear spectral differences in the CH2 (~2920 cm⁻¹) and CH3 (~2956 cm⁻¹) bands reflecting lipid distribution between white and gray matter
• Visualization of amyloid plaques as localized chemical anomalies correlating with protein secondary structure changes
• High spatial fidelity enabling morphological identification of neuropil regions and neuronal cell bodies

These results demonstrate how FTIR chemical imaging can link molecular composition to histological features, providing insights into disease mechanisms.

Benefits and Practical Applications

FTIR imaging offers several advantages for biomedical research:

• Non‐destructive analysis with minimal sample preparation
• High‐throughput screening of large tissue areas at cellular resolution
• Quantitative mapping of biochemical constituents such as lipids and proteins

This makes the technique suitable for preclinical studies, drug monitoring, and quality control in histopathology labs.

Future Trends and Opportunities

Advancements to further enhance FTIR imaging include integration with machine learning for automated feature recognition, coupling with complementary modalities (e.g., Raman or mass spectrometry imaging), and development of higher‐speed detectors. Translation into clinical workflows for real‐time tissue diagnostics is a promising direction.

Conclusion

The Agilent 670/620 FTIR imaging system enables rapid, high‐resolution chemical screening of large tissue sections. By providing molecular and structural information simultaneously, it offers a powerful tool for investigating neurodegenerative diseases and other pathologies.

References

1. Kuzyk A., Kastyak M., Agrawal V., Gallant M., Sivakumar G., Rak M., Del Bigio M., Mai S., Westaway D., Julian R. & Gough K. M. (2010). Association between amyloid plaque, lipid, and creatine in hippocampus of TgCRND8 mouse model for Alzheimer disease. J. Biol. Chem., 285, 31202–31207