## 5 Conclusions  
By comparing the results of the chemical and biological tests of the coatings presented in this paper, it is possible to assess that the attitude of plasma deposited PEO-like coatings, to discourage cell adhesion, tightly depends on their PEO-character, both in the case of LP and AP PE-CVD films. Aerosol assisted AP PE-CVD of non-fouling PEO-like coatings is one order of magnitude faster than the process run at LP (few minutes' vs one-hour). LP PE-CVD, though, allows depositing coatings with better adhesion to the substrate concerning AP processes. To overcome this limit, a multistep AP PE-CVD approach has been proposed in this paper, which led to a dramatic improvement of the stability of PEO-like coating in cell culture experiments. These findings show once again that a correct activation of the underlying substrate, a tightly bound film, and substrate interface, as well as a certain cross-linking degree of the coatings, grant satisfactory film and substrate adhesion also in complex media like cell-culture ones. These characteristics need to match with the correct retention degree of the monomer structure in the coating through a careful optimization of any LP or AP plasma process used. The use of two monomers in soft plasma conditions at LP (i.e., low input power, low carrier gas flow) guarantees the retention of the chemical structure of the monomers, allowing the co-presence of domains with a certain moiety (i.e., ether groups) and domains characterized by another (i.e., ester groups). In soft fragmentation conditions, though, the use of monomers with very low volatility (high boiling point) could compromise this effect. The mixture of two monomers in AP conditions can improve the stability of the coatings in complex media by inducing proper cross-linking, as demonstrated in this paper for coatings deposited by mixtures of ethylene and TEGDME (steps 1 and 2) before depositing the uppermost PEO-like layer.  
The results obtained demonstrate, once again, that properly optimized plasma processes are valid alternatives to conventional coating methods to produce non-fouling and cell adhesive surfaces. When PE-CVDis oriented toward the biomedical field, additional attention is to be paid to control mechanical stresses and material and liquid interactions that generally occurs at the interface with biological entities, that drive, in the end, the success of the surface in the final application.  
The following are available online at [[http://www.mdpi.com/2076-3417/10/24/9101/s1](http://www.mdpi.com/2076-3417/10/24/9101/s1)]([http://www.mdpi.com/2076-3417/10/24/9101/s1](http://www.mdpi.com/2076-3417/10/24/9101/s1)), Figure S1: representative survey spectra, Table S1: XPS chemical composition of PEO-like coatings deposited at LP, Table S2: C1s components, WCA and deposition rate for PEOA and PEO coatings deposited in AP.  
Conceptualization, E.S., F.F. ([PERSON]); methodology, E.S., F.F. ([PERSON]), R.G., G.D.P., J.K.; software, E.S., F.F. ([PERSON]), R.G., V.V.; validation, R.G., E.S.; formal analysis, E.S., F.F. ([PERSON]); investigation, E.S., G.D.P., J.K., F.F. ([PERSON]), R.G.; resources, P.F., F.F. ([PERSON]); data curation, E.S., G.D.P., J.K.; writing--original draft preparation, E.S.; writing--review and editing, all authors; visualization, E.S.; supervision, E.S.; project administration, P.F.; funding acquisition, F.F. ([PERSON]) All authors have read and agreed to the published version of the manuscript.  
This research was funded by Regione Puglia, with the grant \"LIPP\" (grant no. 51, within the Framework Programme Agreement APQ \"Ricerca Scientific\", II atto integrative--Reti di Laboratori Pubblici di Ricerca).  
[PERSON] is gratefully acknowledged for scientific discussion on PE-CVD, [PERSON], and [PERSON] for technical support.  
The authors declare no conflict of interest.