Fig. 1
Enrichment of β-CD-chol in WT FB. Cells were analyzed in basal conditions and after 3 h of incubation with 0.2, 0.6, and 1.0 mg/mL of β-CD-chol. Cells were then probed with the fluorescent dye Filipin III and imaged with wide-field epifluorescence microscopy (a,b). Filipin III fluorescence intensity significantly increases with the increase of β-CD-chol concentration up to 0.6 mg/mL, reaching a fluorescence signal plateau between 0.6 and 1.0 mg/mL. > 30 cells were analyzed for each condition (b). Error bar S.D. Student’s t-test *** p ≤ 0.001. Pre-processing and analysis of Raman spectra. Each raw spectrum (c) was restricted to the range between 2800 cm− 1 and 3026 cm− 1 and smoothed via Savitzky-Golay filtering, with its lowest intensity value subtracted from the whole spectrum (d). The highlighted Raman bands were assigned according to the data reported in17 (see also Supplementary Table T1). Finally, the overall intensities of two Raman bands centered at 2850 cm− 1 and 2898 cm− 1 were computed (e), with their ratio being used as a score for estimating lipid concentration in cells. Raman-SERS analysis of WT FB cells enriched with β-CD-chol in the range 0 − 1 mg/mL. Mean RS (f), SERS (g) and both RS and SERS (h) spectra ± standard errors (SEs) of enriched cells; ratiometric scores measured from RS (i), SERS (j) and both RS and SERS (k) spectra of enriched cells, expressed as percentage variation from the mean control (i.e. 0 mg/mL added, without NPs) value.
