## 2 Materials and Methods
### Chemical and Physical and Biological Characterization of Materials  
XPS measurements were performed with a Theta Probe Thermo VG Scientific instrument (monochromatic Al K\(\alpha\) source). Survey (0-1100 eV) and high-resolution spectra (C1s, O1s) were recorded. Samples were neutralized for electrostatic charging with a flood gun (Mod.822\(-\)06 FG, 1 eV). Angle-resolved (AR) analyses were performed at different take-off angles ranging from 28\({}^{\circ}\) (lowest sampling depth) to 78\({}^{\circ}\) (highest sampling depth). Where not specified a take-off angle of 52\({}^{\circ}\) was used. The take-off angles reported are calculated concerning the sample surface. The hydrocarbon component of the C1s spectrum was used as a reference for the Binding Energy (BE) centered at 285.0 eV; C1s spectra were best-fitted into four peak components: I (285.0 \(\pm\) 0.2 eV, C-H/C), II (286.5 \(\pm\) 0.2 eV, C-OH/OC), III (287.9 \(\pm\) 0.2 eV, C=O/O-C-O), IV (289.2 \(\pm\) 0.2 eV, COOH/C). A full width at half maximum (FWHM) value of 1.5 \(\pm\) 0.2 eV was used for all components. The relative importance of the II component (PEO-character) was related to the non-fouling character of the coatings, as reported in the literature [29; 30]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Deposition Step** & **Name** & \(\phi\)**C\({}_{2}\)H\({}_{4}\) (sccm)** & \(\phi\)**He-TEGDME (slm)** & \(\phi\)**He-Carrier (slm)** & **Va (\(\chi\)V\({}_{\rm p-p}\))** & **f (kHz)** & **t\({}_{\rm d}\) (s)** \\ \hline Step 1 & - & 8 & - & 8 & 8.5 & 16; 26\({}^{\circ}\) & 60 \\ Step 2 & - & 8 & 3.15 & 4.85 & 8.5 & 16; 26\({}^{\circ}\) & 10 \\ Step 3 & PEOA \({}^{\star}\) & - & 3.15 & 4.85 & 6.5; 8.5\({}^{\circ}\) & 16; 26\({}^{\circ}\) & 300 \\  & PEOB \({}^{\star}\) & - & 3.15 & 6.85 & 6.5; 8.5\({}^{\circ}\) & 26 & 300 \\ \hline \multicolumn{8}{l}{\({}^{\star}\) Coatings deposited both as a single step or as the third step of a multi-step approach; \({}^{1}\) coating deposited at 6.5 or 8.5 kV\({}_{\rm p-p}\);\({}^{2}\) coatings deposited at 16 or 26 kHz.} \\ \end{tabular}
\end{table} 
Table 1: Experimental conditions for the three-step deposition. PEOA and PEOB coatings were obtained following the three-step approach by changing respectively the flow rate of the carrier gas (\(\phi\)He-carrier) from 4.85 to 6.85 slm, the applied voltage (Va), the frequency (f) and the deposition time (t\({}_{\rm d}\)). The other parameters like flow of ethylene (\(\phi\)C\({}_{2}\)H\({}_{4}\)) and He flow used in the atomizer to deliver 0.02 g\(\cdot\)min\({}^{-1}\) of TEGDME (\(\phi\)He-TEGDME aerosol) were kept constant. Fourier Transform Infrared Spectroscopy (FT-IR) was used to characterize the bulk of the coatings deposited onto silicon slices. FT-IR spectra (32 scans per analysis, 4 cm\({}^{-1}\) resolution) were obtained in transmission mode with a Vertex 70 V Bruker spectrometer. The spectrometer was evacuated to less than 150 Pa for 10 min before each acquisition. Spectra were elaborated with a Bruker OPUS software and normalized by keeping the peak of CH\({}_{\mathrm{x}}\) stretching (2940-2810 cm\({}^{-1}\)) as reference. Static water contact angle (WCA) was measured with a [PERSON] manual goniometer (model A-100). Static WCA was obtained using 3 \(\mu\)L drops of double-distilled (DD) water. An average value was calculated (3 measurements for each sample, 3 samples per experimental condition). The thickness of the coatings was measured with a AlphaStep(r) D-120 Stylus Profiler, to calculate their deposition rate. The biological experiments performed to test the cytocompatibility of the produced surfaces were done independently with two different types of fibroblast-like cells: Human dermal fibroblasts as a model of primary cells and Saos-2 osteoblast cell lines a model of immortal cell lines widely used for in vitro experiments in the tissue engineering field. Commercial normal human dermal fibroblasts (NHDF adult, Promocell, Germany) were used for the experiments on coatings deposited in LPregime.