Cell Differentiation on Glass Slides with O-PTIR

A paper has been published in Analytical Chemistry about cell type differentiation on glass slides using sub-micron O-PTIR.

Cell Type Differentiation on Glass Slides

There are three key points to the technique:

  • O-PTIR spectra are not affected by Mie-Scattering, so they are highly reproducible.
  • Glass substrates can be used without mid-IR spectral blocking.
  • Combining the spectral ranges delivers >90% accuracy for cell classification.

The paper is entitled “Optical Photothermal Infrared Microspectroscopy Discriminates for the First Time Different Types of Lung Cells on Histopathology Glass Slides”. It’s written by Mustafa Kansiz, Lewis M. Dowling, Ibraheem Yousef, Olivier Guaitella, Ferenc Borondics, and Josep Sulé-Suso.

Studying Biological Samples on Glass Substrates

The use of glass substrates in FT-IR depends highly on the clinical application. Histopathology glass slides of 1 mm thickness absorb the mid-IR spectrum in the rich fingerprint spectral region.

With emerging IR techniques, it’s important to assess whether biological samples can be studied on glass substrates.

For the first time, O-PTIR (Optical Photothermal Infrared spectroscopy) was used to study malignant and non-malignant lung cells. The aim was to identify IR spectral differences between cells placed on standard pathology glass slides.


The feasibility study showed that O-PTIR can be used to acquire good quality IR spectra from cells, from both the lipid region (3000 – 2700 cm–1) and the fingerprint region between 1770 and 950 cm –1. Between 1350 to 950 cm –1 there were glass contributions.

A new single-unit dual-range (C–H/FP) quantum cascade laser (QCL) IR pump source was used for the first time. This delivered a clear synergistic benefit to the classification results.

Furthermore, O-PTIR could distinguish between lung cancer cells and non-malignant lung cells in both the lipid and fingerprint regions.

Combining the two spectral ranges increased the accuracy, with Random Forest modeling classification accuracy results ranged from 96 to 99% across all three cell lines.

This is the first publication using a single-unit dual-range QCL for O-PTIR on glass, which represents a significant step toward its clinical application in pathology.

Read the Scientific Paper

The full paper’s published in Analytical Chemistry – read it online here (log-in/purchase required):

O-PTIR Scientific Paper


The O-PTIR system used in this research is the mIRage IR microscope from Photothermal Spectroscopy Corp:

mIRage IR Microscope


  • Sub-micron IR spectroscopy and imaging.
  • Non-contact – fast and easy to use.
  • Transmission quality IR spectra in reflection mode.
  • No need for thin sections.

More Information

BlueScientific is the official distributor for Photothermal Spectroscopy Corp in the UK, Ireland and Nordic region. We’re available to answer all your questions – just get in touch:

  Contact us on +44 (0)1223 422 269 or info@blue-scientific.com

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