Fig. 1. Image analysis and MCR-ALS analysis.

a White light Image of the cell. Lipid droplets can be identified as globules. Scale bar 10 μm. b LD boundaries. c Spatial distribution of intensity of alkyne bond stretching mode (2119 cm⁻¹) of alkyne cholesterol. d Statistically significant spectral components separated in the MCR-ALS analysis. We have assigned them as, 1—Oleate, 2—Polyunsaturated lipid, 3—Polar lipid, 4—Nucleic Acids and Proteins, 5—Proteins, 6—Alkyne cholesterol, 7—Cholesterol. There were also broad background spectral components without any substantially biological spectral features. The full list of spectral components is given in Supplementary Fig. 1. The accuracy of the analysis is clear from the negligible residual (Supplementary Fig. 2). e A pictorial depiction of the modified MCR-ALS routine used in this study. A linear combination of the separated profiles (background and signal) gives the total Raman spectrum.