Raman Spectroscopy Analysis of Liposome Samples

Raman spectral data were collected using a Nicolet NXR 9650 FT-Raman spectrometer (Thermo Scientific, USA), which includes a MicroStage extension, a neodymium-doped yttrium orthovanadate (Nd: YVO4) laser operating at 1064 nm with a power of 100 mW for excitation, and an indium gallium arsenide (InGaAs) detector for signal detection. Each analysis involved placing a 10 μL drop of the sample liposome suspension onto a gold substrate, which was then allowed to dry via exposure to the laser. The FT-Raman spectra captured a frequency range from 3700 to 0 cm⁻¹, achieving a resolution of 4 cm⁻¹ by averaging over 1024 scans (Fig. S7). The study maintained a consistent concentration of the compounds at 50 μM and lipids at 0.1 mg/ml to optimize the signal-to-noise ratio. Spectral acquisition was performed immediately following the dissolution of samples. Spectral processing and analysis were conducted using OriginPro 2021 software (Origin Lab Corporation, Northampton, Massachusetts, United States), with procedures including baseline adjustment, Savitzky-Golay (SG) smoothing with a window of 35 points and a polynomial order of 2, and normalization of spectra within the [0–1] range for the specific band region under investigation.