Enhanced characterization of breast cancer phenotypes using Raman micro-spectroscopy on stainless steel substrate

• Published in: Analytical methods 2023-03, Vol.15 (9), p.1188-125
• Main Authors: Thomas, Giju, Fitzgerald, Sean T, Gautam, Rekha, Chen, Fuyao, Haugen, Ezekiel, Rasiah, Pratheepa Kumari, Adams, Wilson R, Mahadevan-Jansen, Anita
• Format: Article
• Language: English
• Subjects: Biochemistry; Breast cancer; Breast Neoplasms; Calcium fluoride; Coherent scattering; ErbB-2 protein; Female; Fluorides; Growth factors; Humans; Lasers; Lipogenesis; Metabolism; Pathogenesis; Phenotype; Phenotypes; Raman spectra; Raman spectroscopy; Signal quality; Signal to noise ratio; Spectral analysis; Spectroscopy; Spectrum analysis; Spectrum Analysis, Raman; Stainless steel; Stainless Steel - chemistry; Stainless steels; Substrates; Therapeutic targets
• ISSN: 1759-9660; 1759-9679
• DOI: 10.1039/d2ay01764d

Biochemical insights into varying breast cancer (BC) phenotypes can provide a fundamental understanding of BC pathogenesis, while identifying novel therapeutic targets. Raman spectroscopy (RS) can gauge these biochemical differences with high specificity. For routine RS, cells are traditionally seeded onto calcium fluoride (CaF 2 ) substrates that are costly and fragile, limiting its widespread adoption. Stainless steel has been interrogated previously as a less expensive alternative to CaF 2 substrates, while reporting increased Raman signal intensity than the latter. We sought to further investigate and compare the Raman signal quality measured from stainless steel versus CaF 2 substrates by characterizing different BC phenotypes with altered human epidermal growth factor receptor 2 (HER2) expression. Raman spectra were obtained on stainless steel and CaF 2 substrates for HER2 negative cells - MDA-MB-231, MDA-MB-468 and HER2 overexpressing cells - AU565, SKBr3. Upon analyzing signal-to-noise ratios (SNR), stainless steel provided a stronger Raman signal, improving SNR by 119% at 1450 cm −1 and 122% at 2925 cm −1 on average compared to the CaF 2 substrate. Utilizing only 22% of laser power on sample relative to the CaF 2 substrate, stainless steel still yielded improved spectral characterization over CaF 2 , achieving 96.0% versus 89.8% accuracy in BC phenotype discrimination and equivalent 100.0% accuracy in HER2 status classification. Spectral analysis further highlighted increased lipogenesis and altered metabolism in HER2 overexpressing cells, which was subsequently visualized with coherent anti-Stokes Raman scattering microscopy. Our findings demonstrate that stainless steel substrates deliver improved Raman signal and enhanced spectral characterization, underscoring its potential as a cost-effective alternative to CaF 2 for non-invasively monitoring cellular biochemical dynamics in translational cancer research. Stainless steel yields stronger Raman signal intensity than the traditional CaF 2 substrate, demonstrating potential for improved spectral characterization which further reveals increased lipogenesis in HER2 overexpressing breast cancer cells.