**4. Conclusions**

The N-Palmitoyl-(4-nitro-phenyl)-amine, PNPA, a PEA derivative that already showed good anti-inflammatory and antioxidant properties, was firmly entrapped in a sol–gel-based matrix obtained by polymerization reaction of the epoxy-alkoxysilane GPTES, as cross-linker compound. NMR studies run on the sol evidenced that the GPTES epoxy-ring opening and the subsequent polymerization give rise to a polyethylene oxide 3D network grafted on textile with the PNPA immobilized into it. After the textile drying and curing the xerogel was morphologically studied on the treated cotton samples by SEM and AFM microscopy, revealing that no changes in the fiber morphology occurred at the micrometer scale, and that GPTES and PNPA intimately and homogeneously wrap the fibers. Furthermore, SEM mapping revealed a uniform distribution of the silica-based coating on the cotton fibers. In vitro diffusion studies were realized on the developed functionalized cotton-based textiles in order to check their ability to release the PEA derivative in a controlled manner in comparison to a standard molecule solution. As a matter of fact, this functional textile has been shown to be a suitable system for PNPA release, thanks to the chemical binding weakening of PNPA with the sol–gel polymer matrix by mean of medium effect, thus opening the way to the design of similar functional hybrid coatings for biomedical application. Although parameters of sol particles (e.g., hydrodynamic radius and electrokinetic potential) as well as the porosity of systems were not investigated, the obtained results confirmed the potential of the nanoengineered procedure as a versatile method for preparing stable and tunable drug-releasing materials. The combination of the functionality and transparency provided by the hybrid coating with its easy processability could represent an innovative route to fabricate biomaterials for healthcare. Future work will focus on the comparison of silica sols characteristics with release properties of this delivery system.

**Author Contributions:** Conceptualization was done by M.S.S., G.R. and M.R.P. Investigation was performed by F.P., O.I.P., C.S., M.G.B., V.T., G.R., C.T., C.M., E.P., M.S.S., D.I., M.R.P. and D.D. Project administration was directed by M.S.S., G.R. and M.R.P. Resources were provided by F.P., O.I.P., C.S., M.G.B., V.T., G.R., C.T., C.M., E.P., M.S.S., D.I., M.R.P. and D.D. Supervision was taken care of by M.S.S., G.R. and M.R.P. Validation was carried out by F.P. and O.I.P. Visualization and original draft writing was done by M.S.S., G.R. and M.R.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** MURST: CNR and MIUR are gratefully acknowledged for financial support.

**Conflicts of Interest:** The authors declare no conflict of interest.
