High Spatial resolution FTIR imaging of biomedical tissue samples using a novel method of magnification enhancement

Importance of the Topic

Fourier transform infrared imaging is important for mapping chemical distributions in biological tissues. Achieving sub micron spatial resolution extends its use for studying microstructures in disease research enabling detailed chemical mapping of pathological features like amyloid plaques.

Goals and Study Overview

This work introduces a magnification enhancement method using existing microscope objectives to improve FTIR imaging resolution to 1 micron per pixel while preserving a large working distance of 21 millimeters. Performance is compared to standard FTIR microscopy and synchrotron based imaging.

Methodology and Instrumentation

• Instrument Agilent Cary 670 FTIR spectrometer with Cary 620 microscope and high energy globar source.
• Standard versus high magnification modes achieved by software controlled stage and optics enhancement without objective exchange.
• Comparison with multi beam synchrotron IRENI using a non Agilent system.
• Key parameters pixel size reduced from 5.5 to 1.1 microns spectral resolution 4 cm-1 acquisition times 6 minutes for a 140 by 140 micron tile.

Main Results and Discussion

High magnification FTIR produced clear chemical images of Alzheimer model mouse brain with spectral quality comparable or better than synchrotron data. Enhanced spatial resolution revealed smaller and more concentrated chemical inclusions that were averaged out at lower resolution. Images of plaque cores and lipid infiltration displayed fine structural details. Spectral artefacts observed in synchrotron data at low wavenumbers were absent in the Agilent globar source images.

Practical Benefits and Applications

• Improved detection and mapping of micron scale chemical features in biomedical samples.
• Faster data collection due to larger field of view and no objective changes.
• Maintained working distance supports analysis of various sample formats.

Future Trends and Applications

Integration of software magnification enhancement may become standard in FTIR imaging for biomedical and materials science research. Further developments could extend resolution beyond diffraction limits and combine with chemometric methods to deepen molecular insights in disease studies quality control and industrial analysis.

Conclusion

The novel magnification enhancement method delivers high spatial resolution FTIR imaging approaching 1 micron per pixel without sacrificing working distance or requiring synchrotron sources. It outperforms standard configurations and matches synchrotron performance while offering faster tile acquisition and simplified workflow.

Reference

• Nasse N et al Nature Methods 2011 8 413 418
• Liao R Rak A et al NeuroImage 2012 138 3991 3997