Figure 3

Principal Component Analysis (PCA) was conducted on S-FTIR data. HCT116 cells were treated at different concentrations (26 and 34 µg/mL) within the spectral range of 3000–2800 cm⁻¹ and 1800–900 cm⁻¹ regions. In the PCA analysis, PC1 and PC2 accounted for 44% and 15% of the total variance, respectively. (a) The PCA 2D score plot illustrated the distribution of samples based on PC1 and PC2. (b) The loading plot displayed the contributions of PC1 and PC2 to the overall spectral variations. (c–e) The second derivative spectra of the lipid regions (3000–2800 cm⁻¹), amide regions (1740–1600 cm⁻¹), and nucleic acid, and other carbohydrate regions (1300–1000 cm⁻¹) were averaged separately.