Ccd detector

Raman spectra were obtained using a HORIBA LabRAM HR Evolution equipped with a 532 nm laser. The Raman spectrometer is coupled to a CCD detector (Horiba) and a microscope equipped with a 100× magnification objective. A grating of 1800gr/mm was used to obtain high spectral resolution. For each sample, three spectra were recorded and averaged, peak area and maximum were determined by the application of a polynomial baseline and fitting with a Lorentzian function.
Spectra in the radial breathing mode (RBM) range were acquired with a 532 nm laser with 900 gr/mm, 100% ND filter, 10 s acquisition time and four accumulations in the range of 100 to 500 cm⁻¹. From the mappings two representative spectra were selected for each sample.

SERS spectra were measured using a single-stage spectrograph equipped with a CCD detector (Horiba, Munich, Germany) and a diode operating at 785 nm (Toptica, Graefelfing, Germany), in a setup with a 180 degree backscattering geometry. A 60× water immersion objective (NA = 1.2) was used in the experiments with cells, and the excitation intensity on the samples was 8 × 10⁵ W cm⁻². All spectra were obtained with an acquisition time of 1 s, and the spectral resolution was 4–7 cm⁻¹ considering the whole recorded spectral range (400–1800 cm⁻¹). From 3T3 cells, 489 spectra from 15 cells were obtained for 3 h incubation with NS25, and 232 spectra were obtained from 6 cells for 6 h incubation. From HCT-116 cells, 100 spectra from 8 cells were measured for 3 h incubation with NS25, and 207 spectra were obtained from 7 cells for 6 h incubation. J774 cells spectra analysis was done with 370 spectra from 7 cells exposed to NS25, 252 spectra from 9 cells exposed to NS50, and 226 spectra from 10 cells exposed to NS75, all after an incubation time of 3 h. Processing of the spectra with Matlab R2018a (The MathWorks, Inc., Natick, MA, USA) included frequency calibration, baseline correction, and vector normalization. Band occurrence calculation was performed with Wolfram Mathematica 12 software.