Fig. 4. Identification plots for the PLS-DA model constructed using Raman spectra acquired from individual, living (a) CHO, (b) CHO-T, and (c) MDCK cells encapsulated in gelMA hydrogels. Cells located above the classification threshold denoted by the red dashed line were identified as (a) CHO cells ( and , n_model = 62, n_test = 61), (b) CHO-T cells ( and , n_model = 62, n_test = 61), and (c) MDCK cells ( and , n_model = 60, n_test = 59). Variable importance for prediction (VIP) plots for (d) CHO cells, (e) CHO-T cells, and (f) MDCK cells show which peaks have high (>1) scores that denote importance for identifying that cell type. Assignment of labeled peaks: 664 cm⁻¹ (DNA bases), 680 cm⁻¹ (DNA bases), 700 cm⁻¹ (methionine), 716 cm⁻¹ (lipids), 733 cm⁻¹ (phosphatidylserine), 782 cm⁻¹ (DNA/RNA), 789 cm⁻¹ (phosphodiester bands), 956 cm⁻¹ (cholesterol), 1015 cm⁻¹ (carbohydrates), 1022 cm⁻¹ (glycogen), 1442 cm⁻¹ (fatty acids and collagen), and 1585 cm⁻¹ (phenylalanine and hydroxyproline).