Gold Nanorods Based Air Scanning Electron Microscopy and Diffusion Reflection Imaging for Mapping Tumor Margins in Squamous Cell Carcinoma

A critical challenge arising during
a surgical procedure for tumor
removal is the determination of tumor margins. Gold nanorods (GNRs)
conjugated to epidermal growth factor receptors (EGFR) (GNRs-EGFR)
have long been used in the detection of cancerous cells as the expression
of EGFR dramatically increases once the tissue becomes cancerous.
Optical techniques for the identification of these GNRs-EGFR in tumor
are intensively developed based on the unique scattering and absorption
properties of the GNRs. In this study, we investigate the distribution
of the GNRs in tissue sections presenting squamous cell carcinoma
(SCC) to evaluate the SCC margins. Air scanning electron microscopy
(airSEM), a novel, high resolution microscopy is used, enabling to
localize and actually visualize nanoparticles on the tissue. The airSEM
pictures presented a gradient of GNRs from the tumor to normal epithelium,
spread in an area of 1 mm, suggesting tumor margins of 1 mm. Diffusion
reflection (DR) measurements, performed in a resolution of 1 mm, of
human oral SCC have shown a clear difference between the DR profiles
of the healthy epithelium and the tumor itself.