Nanoscale-Sensitive VSFG Microscopy for Identifying Breast Tumor in FFPE Samples

Area of Science:

• Biophysics
• Cancer Research
• Biomedical Imaging

Background:

• Nanoscale collagen remodeling is a key indicator of tumor development and metastasis.
• Vibrational sum-frequency generation (VSFG) microscopy detects these nanostructural changes in Optimal Cutting Temperature (OCT) samples.
• Clinical tissues are typically processed as formalin-fixed, paraffin-embedded (FFPE) blocks, raising concerns about VSFG's applicability.

Purpose of the Study:

• To determine if VSFG microscopy can effectively analyze deparaffinized FFPE tissues.
• To assess if FFPE processing preserves the nanoscale structural cues crucial for VSFG detection.
• To evaluate the potential of VSFG for clinical workflows and retrospective studies using FFPE archives.

Main Methods:

• Deparaffinization of FFPE tissues followed by VSFG microscopy.
• Analysis of VSFG spectra, chemical images, and collagen ratio (I_NHs/I_CH2,Ss).
• Complementary atomic force microscopy (AFM) nanomechanics measurements.

Main Results:

• VSFG microscopy remains fully effective in deparaffinized FFPE tissues.
• Key diagnostic metrics, including VSFG spectra and collagen ratio, were statistically indistinguishable from OCT controls.
• AFM nanomechanics corroborated the preservation of structural integrity.

Conclusions:

• VSFG imaging is viable for standard clinical workflows and analysis of FFPE tissue archives.
• This opens avenues for retrospective prognostic studies and label-free diagnostics in cancer research.
• FFPE processing does not destroy the subtle structural cues detected by VSFG.