*2.4. ATR-FTIR*

In order to characterize the chemical changes on the Sil surface, the samples were analyzed by ATR-FTIR. The changes in characteristic IR bands indicate a chemical change in the surface composition. Significant differences in the range of 3500–3000 cm<sup>−</sup><sup>1</sup> and 1800–1700 cm<sup>−</sup><sup>1</sup> can be seen comparing the IR spectra Sil, Sil-GOPS, Sil-PLLA-NH2 and Sil-PLLA (Figure 3). Furthermore, the IR spectra for all PLLA coated silicone samples Sil-PLLA-NH2 and Sil-PLLA reveal a prominent band around 1751 cm<sup>−</sup><sup>1</sup> (Figure 3), which denotes carbonyl (C=O) stretching vibration, characteristic for ester bonds found in the used coating polymers. Furthermore, all FTIR spectra for the investigated samples were compared with the specific material used, shown in the supporting materials (Figures S3–S5, Supplementary Materials).
