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

Significance of the Topic

Infrared imaging provides non-destructive, high-resolution chemical mapping of biological tissues, enabling detailed investigation of disease-related changes in molecular composition and structure. In Alzheimer’s research, correlating protein aggregates and lipid distribution with tissue morphology offers critical insights into neuronal degradation and pathology progression.

Objectives and Study Overview

The primary goal was to evaluate the feasibility of rapid, large-area screening of a full mouse hippocampus section using Fourier-transform infrared (FTIR) imaging. Researchers sought to determine how chemical composition and protein secondary structure correlate with histological features such as amyloid plaques and neurofibrillary tangles, thereby advancing understanding of Alzheimer’s disease mechanisms.

Methodology and Instrumentation

Sample analysis combined an Agilent Cary 670 FTIR spectrometer with an Agilent Cary 620 FTIR microscope equipped with a 64×64 focal plane array (FPA) detector. Key parameters included:

• Spatial resolution: 5.5 µm pixel size
• Spectral resolution: 4 cm⁻¹
• Scan rate: 5 kHz
• Scans per pixel: 128 co-adds
• Imaging mode: Reflection mosaic (4×6 tiles)

Mosaic imaging extended the field of view to cover the 1.4 mm×2.2 mm hippocampus in a single experiment. Automated data acquisition and processing were performed with Agilent Resolutions Pro software, enabling unattended, high-throughput spectral collection over large areas.

Key Results and Discussion

In under 30 minutes, the system acquired approximately 100 000 spectra at cellular resolution. Multivariate visualization produced two- and three-dimensional chemical maps distinguishing white matter, gray matter, and neuronal structures. Spectral analysis in the CH stretching region (around 2730 cm⁻¹) revealed marked differences in CH₂ and CH₃ band intensities, indicating lipid enrichment in myelinated axons (white matter) versus protein-rich gray matter. Morphological features such as amyloid plaques and neurofibrillary tangles were chemically resolved, demonstrating the method’s ability to link biochemical composition with pathological hallmarks.

Benefits and Practical Applications

• Rapid, large-area imaging at cellular resolution accelerates screening workflows.
• Minimal sample preparation preserves native tissue chemistry.
• Non-destructive analysis retains samples for complementary assays.
• Detailed chemical maps support biomarker discovery and drug evaluation.

Future Trends and Potential Applications

Advancements may include integration with complementary imaging modalities (e.g., Raman, mass spectrometry imaging), development of enhanced FPA detectors for faster acquisition, and application of machine learning algorithms for automated feature recognition. Such innovations will expand throughput, sensitivity, and diagnostic capabilities in biomedical and clinical research.

Conclusion

Agilent’s FTIR imaging platform enables rapid, high-resolution chemical characterization of large biological samples, offering unique insights into Alzheimer’s pathology at the cellular level. This non-destructive approach fosters a deeper understanding of disease processes and supports the ongoing search for diagnostic markers and therapeutic targets.

References

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. Journal of Biological Chemistry 285:31202–31207.