File Name : supplementary figure 1.tif Caption : supplementary figure 1: ftir mean spectra of pgsa-745 lysate (protein concentration of 1 µg/µl) spiked with increasing amounts of chondroitin sulfate e (cse) (black: 0 µg, green: 0.05 µg, blue: 0.5 µg, purple: 5 µg, and red: 50 µg). the characteristic peaks of cse can be observed, along with the characteristic peaks of cell lysate. this allows us to determine the detection limit of cse by ftir, which is 5 µg. peak assignments are as follows: 927 cm⁻¹ (c–o–s, cse), 1043 cm⁻¹ (s c–o, cse), 1065 cm⁻¹ (s s=o, cse), 1125 cm⁻¹ (oligosaccharides, cse), 1248 cm⁻¹ (as s=o, cse), 1375 cm⁻¹ (c–c, cse), 1410 cm⁻¹ (s coo⁻, cse), 1450 cm⁻¹ (ch₂, lipids and proteins), 1540 cm⁻¹ (amide ii, proteins), 1565 cm⁻¹ (n–h, cse), 1620 cm⁻¹ (as coo⁻, cse), 1650 cm⁻¹ (amide i, proteins), 1720 cm⁻¹ (c=o, fatty acids). s: symmetric vibration and as: anti-symmetric vibration.