*2.3. DSPE–HA Conjugate Analysis*

The conjugation products were analyzed with nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FT-IR). The <sup>1</sup>H-NMR analysis was performed with a 400 MHz NMR Bruker AVANCE-III HD spectrometer (Bruker BioSpin, Rheinstetten, Germany). For the measurement, DSPE was dissolved in deuterated chloroform (CDCl3), whereas the DSPE–HA conjugate was dissolved in deuterated dimethyl sulfoxide (DMSO-*d6*).

A Vertex 70 FT-IR spectrometer (Bruker Optics, Ettlingen, Germany) equipped with a MIRacle attenuated total reflectance attachment was used in the FT-IR analysis, so that a tiny amount of either DSPE or DSPE–HA conjugate was placed on a diamond single-bounce crystal (Pike Technologies, Fitchburg, WI, USA). The scan was performed in the 650–4000 cm−<sup>1</sup> wavelength range, while the spectral resolution was 4 cm−<sup>1</sup> . The background signal measured from a blank crystal was deducted from the average of 256 scans with Opus software.
