Fig. 3. Identification plots for the PLS-DA model constructed using Raman spectra of acquired from individual, living (a) CHO, (b) CHO-T, and (c) MDCK cells encapsulated in collagen hydrogels identify the lineage of each cell. Markers located above the classification threshold (red dashed line) indicate that cell was identified as a (a) CHO cell (red diamonds, n_model = 23, n_test = 22), (b) CHO-T cell (green squares, n_model = 23, n_test = 22), or (c) MDCK cell (blue triangles, n_model = 20, n_test = 19). Variable importance for prediction (VIP) scores plots for (d) CHO cells, (e) CHO-T cells, and (f) MDCK cells encapsulated in collagen hydrogels show the VIP scores for various Raman peaks. Peaks with high (>1) scores are important for identifying the indicated cell type. Assignments of labeled peaks: 685 cm⁻¹ (citric acid), 698 cm⁻¹ (methionine), 860 cm⁻¹ (tyrosine, collagen, and phosphates), 883 cm⁻¹ (proteins), 1061 cm⁻¹ (proteins), 1076 cm⁻¹ (lipids), 1422 cm⁻¹ (adenine, guanine, and deoxyribose), and 1438 cm⁻¹ (lipids).